 Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 124 journals)
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- Aerospace, Vol. 10, Pages 744: Comparison of Actual and Time-Optimized
Flight Trajectories in the Context of the In-Service Aircraft for a Global
Observing System (IAGOS) Programme
Authors: Olivier Boucher, Nicolas Bellouin, Hannah Clark, Edward Gryspeerdt, Julien Karadayi
First page: 744
Abstract: Airlines optimize flight trajectories in order to minimize their operational costs, of which fuel consumption is a large contributor. It is known that flight trajectories are not fuel-optimal because of airspace congestion and restrictions, safety regulations, bad weather and other operational constraints. However, the extent to which trajectories are not fuel-optimal (and therefore CO2-optimal) is not well known. In this study, we present two methods for optimizing the flight cruising time by taking best advantage of the wind pattern at a given flight level and for constant airspeed. We test these methods against actual flight trajectories recorded under the In-service Aircraft for a Global Observing System (IAGOS) programme. One method is more robust than the other (computationally faster) method, but when successful, the two methods agree very well with each other, with optima generally within the order of 0.1%. The IAGOS actual cruising trajectories are on average 1% longer than the computed optimal for the transatlantic route, which leaves little room for improvement given that by construction the actual trajectory cannot be better than our optimum. The average degree of non-optimality is larger for some other routes and can be up to 10%. On some routes, there are also outlier flights that are not well optimized; however, the reason for this is not known.
Citation: Aerospace
PubDate: 2023-08-23
DOI: 10.3390/aerospace10090744
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 745: A Study on Thermal Management Systems for
Hybrid–Electric Aircraft
Authors: Maria Coutinho, Frederico Afonso, Alain Souza, David Bento, Ricardo Gandolfi, Felipe R. Barbosa, Fernando Lau, Afzal Suleman
First page: 745
Abstract: The electrification of an aircraft’s propulsive system is identified as a potential solution towards a lower carbon footprint in the aviation industry. One of the effects of increased electrification is the generation of a large amount of waste heat that needs to be removed. As high-power systems must be cooled to avoid performance deterioration such as battery thermal runaway, a suitable thermal management system is required to regulate the temperature of the powertrain components. With this in mind, the main objective of this research is to identify promising heat transfer technologies to be integrated into a thermal management system (TMS) such that power, mass, and drag can be minimised for a parallel hybrid–electric regional aircraft in the context of the EU-funded FutPrInt50 project. Five different TMS architectures are modelled using the Matlab/Simulink environment based on thermodynamic principles, heat transfer fundamentals, and fluid flow equations. The systems are a combination of a closed-loop liquid cooling integrated with different heat dissipation components, namely ram air heat exchanger, skin heat exchanger, and fuel. Their cooling capacity and overall aircraft performance penalties under different flight conditions are estimated and compared to each other. Then, a parametric study is conducted, followed by a multi-objective optimisation analysis with the aim of minimising the TMS impact. As expected, none of the investigated architectures exhibit an ideal performance across the range of the studied metrics. The research revealed that, while planning the TMS for future hybrid–electric aircraft, alternative architectures will have to be developed and studied in light of the power requirements.
Citation: Aerospace
PubDate: 2023-08-23
DOI: 10.3390/aerospace10090745
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 746: A Generic Model for Benchmark Aerodynamic
Analysis of Fifth-Generation High-Performance Aircraft
Authors: Nicholas F. Giannelis, Tamas Bykerk, Gareth A. Vio
First page: 746
Abstract: This paper introduces a generic model for the study of aerodynamic behaviour relevant to fifth-generation high-performance aircraft. The model design is presented, outlining simplifications made to retain the key features of modern high-performance vehicles while ensuring a manufacturable geometry. Subsonic wind tunnel tests were performed with force and moment balance measurements used to develop a database of experimental validation data for the platform at a freestream velocity of 20 m/s. Numerical simulations are also presented and validated by the experiments and further employed to ensure the vortex behaviour is consistent with contemporary high-performance platforms. A sensitivity study of the computational predictions from the turbulence modelling approach is also presented. This geometry is the first in a suite of representative aircraft geometries (the Sydney Standard Aerodynamic Models), in which all geometries, computational models, and experimental data are made openly available to the research community (accessible via this link: https://zenodo.org/communities/ssam_gen5/) to serve as validation test cases and promote best practices in aerodynamic modelling.
Citation: Aerospace
PubDate: 2023-08-23
DOI: 10.3390/aerospace10090746
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 747: Dynamic Surface-Based Adaptive Active
Disturbance Rejection Control of Electrohydrostatic Actuators
Authors: Xudong Han, Yongling Fu, Yan Wang, Mingkang Wang, Deming Zhu
First page: 747
Abstract: The control accuracy and stability of the electrohydrostatic actuator (EHA) are directly impacted by parameter uncertainty, disturbance uncertainty, and non-matching disturbance, which negatively impacts aircraft rudder maneuvering performance and even results in rudder chatter. A dynamic surface-based adaptive active disturbance rejection control (DSAADRC) is proposed as a solution for these issues. It does this by developing a novel parametric adaptive law driven by the combination of tracking error, parameter estimation error, and state estimation error to estimate the unknown parameters, using three low-order ESOs to estimate and compensate the uncertain disturbances online, and employing a dynamic surface method to obtain the differential values of virtual control signals in the backstepping method to deal with non-matching disturbances. In this research, a Lyapunov stability analysis demonstrates that the method can achieve the position tracking accuracy of the EHA under time-varying external disturbances after first establishing an EHA dynamics model with nonlinearity and uncertainty, followed by the design of an adaptive active disturbance rejection control method based on dynamic surfaces for the uncertainties and perturbations. In contrast to control strategies like Robust Control (RC) and Adaptive Robust Control (ARC), simulation and experiment comparison shows that the method has stronger anti-disturbance under time-varying external disturbances.
Citation: Aerospace
PubDate: 2023-08-23
DOI: 10.3390/aerospace10090747
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 748: Star-Identification System Based on Polygon
Recognition
Authors: Gustavo E. Ramos-Alcaraz, Miguel A. Alonso-Arévalo, Juan M. Nuñez-Alfonso
First page: 748
Abstract: Accurate attitude determination is crucial for satellites and spacecraft. Among attitude determination devices, star sensors are the most accurate. Solving the lost-in-space problem is the most critical function of the star sensor. Our research introduces a novel star-identification system that utilizes a polygon-recognition algorithm to assign a unique complex number to polygons created by stars. This system aims to solve the lost-in-space problem. Our system includes a full solution with a lens, image sensor, processing unit, and algorithm implementation. To test the system’s performance, we analyzed 100 night sky images that resembled what a real star sensor in orbit would experience. We used a k-d tree algorithm to accelerate the search in the star catalog of complex numbers. We implemented various verification methods, including internal polygon verification and a voting mechanism, to ensure the system’s reliability. We obtained the star database used as a reference from the Gaia DR2 catalog, which we filtered, to eliminate irrelevant stars, and which we arranged by apparent magnitude. Despite manually introducing up to three false stars, the system successfully identified at least one star in 97% of the analyzed images.
Citation: Aerospace
PubDate: 2023-08-24
DOI: 10.3390/aerospace10090748
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 749: Aerodynamic Characteristics of a Z-Shaped
Folding Wing
Authors: Yongchang Huang, Xiangying Guo, Dongxing Cao
First page: 749
Abstract: Z-shaped folding wings have the potential to enhance the flight performance of an aircraft, contingent upon its mission requirements. However, the current scope of research on unmanned aerial vehicles (UAVs) with Z-shaped folding wings primarily focuses on the analysis of their folding structure and aeroelasticity-related vibrations. Computational fluid dynamics methods and dynamic meshing are employed to examine the folding process of Z-shaped folding wings. By comparing the steady aerodynamic characteristics of Z-shaped folding wings with those of conventional wings, this investigation explores the dynamic aerodynamic properties of Z-shaped folding wings at varying upward folding speeds. The numerical findings reveal that the folding of Z-shaped folding wings reduces the lift-to-drag ratio, yet simultaneously diminishes the nose-down pitching moment, thereby augmenting maneuverability. Concerning unsteady aerodynamics, the transient lift and drag coefficients of the folded wing initially increase and subsequently decrease as the folding angle increases at small angles of attack. Likewise, the nose-down pitching moment exhibits the same pattern in response to the folding angle. Additionally, the aerodynamic coefficients experience a slight decrease during the initial half of the folding process with increasing folding speed. Once the wing reaches approximately 40°~45° of folding, there is an abrupt change in the transient aerodynamic coefficients. Notably, this abrupt change is delayed with higher folding speeds, eventually converging to similar values across different folding speeds.
Citation: Aerospace
PubDate: 2023-08-24
DOI: 10.3390/aerospace10090749
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 750: Parametric Analysis of the Toothed
Electromagnetic Spring Based on the Finite Element Model
Authors: Xiaoyuan Zheng, Cheng Zhang, Yifang Lou, Guangming Xue, Hongbai Bai
First page: 750
Abstract: Active vibration control shows excellent performance in vibration isolation. In this work, the finite element model of a toothed electromagnetic spring (TES) is established using ANSYS Maxwell software. Subsequently, a static characteristic experiment of the TES is carried out, and the validity of the model is verified. Based on the established finite element model, the influence of key structural parameters on the static characteristics of the electromagnetic spring is analyzed. The results show that the parameters of the magnetic teeth have a significant impact on the performance of the electromagnetic spring. As the number of teeth increases, the electromagnetic force first increases and then decreases. With the increase in the tooth height or width, the maximum electromagnetic force gradually increases to the maximum value and then stabilizes. It should be noted that the tooth width simultaneously affects the maximum electromagnetic force, stiffness characteristics, and effective working range of the TES. This work provides a basis for further exploring the application of electromagnetic springs within the field of active vibration control.
Citation: Aerospace
PubDate: 2023-08-25
DOI: 10.3390/aerospace10090750
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 751: Parameter-Free Shape Optimization: Various
Shape Updates for Engineering Applications
Authors: Lars Radtke, Georgios Bletsos, Niklas Kühl, Tim Suchan, Thomas Rung, Alexander Düster, Kathrin Welker
First page: 751
Abstract: In the last decade, parameter-free approaches to shape optimization problems have matured to a state where they provide a versatile tool for complex engineering applications. However, sensitivity distributions obtained from shape derivatives in this context cannot be directly used as a shape update in gradient-based optimization strategies. Instead, an auxiliary problem has to be solved to obtain a gradient from the sensitivity. While several choices for these auxiliary problems were investigated mathematically, the complexity of the concepts behind their derivation has often prevented their application in engineering. This work aims to explain several approaches to compute shape updates from an engineering perspective. We introduce the corresponding auxiliary problems in a formal way and compare the choices by means of numerical examples. To this end, a test case and exemplary applications from computational fluid dynamics are considered.
Citation: Aerospace
PubDate: 2023-08-25
DOI: 10.3390/aerospace10090751
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 752: Assessment of Asteroid Classification Using
Deep Convolutional Neural Networks
Authors: Victor Bacu, Constantin Nandra, Adrian Sabou, Teodor Stefanut, Dorian Gorgan
First page: 752
Abstract: Near-Earth Asteroids represent potential threats to human life because their trajectories may bring them in the proximity of the Earth. Monitoring these objects could help predict future impact events, but such efforts are hindered by the large numbers of objects that pass in the Earth’s vicinity. Additionally, there is also the problem of distinguishing asteroids from other objects in the night sky, which implies sifting through large sets of telescope image data. Within this context, we believe that employing machine learning techniques could greatly improve the detection process by sorting out the most likely asteroid candidates to be reviewed by human experts. At the moment, the use of machine learning techniques is still limited in the field of astronomy and the main goal of the present paper is to study the effectiveness of deep convolutional neural networks for the classification of astronomical objects, asteroids in this particular case, by comparing some of the well-known deep convolutional neural networks, including InceptionV3, Xception, InceptionResNetV2 and ResNet152V2. We applied transfer learning and fine-tuning on these pre-existing deep convolutional networks, and from the results that we obtained, the potential of using deep convolutional neural networks in the process of asteroid classification can be seen. The InceptionV3 model has the best results in the asteroid class, meaning that by using it, we lose the least number of valid asteroids.
Citation: Aerospace
PubDate: 2023-08-25
DOI: 10.3390/aerospace10090752
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 753: Feasibility and Performance Analysis of
High-Energy-Density Hydrocarbon-Fueled Turboexpander Engine
Authors: Jin Gao, Ziyi Kang, Weiheng Sun, Youyin Wang, Junlong Zhang, Wen Bao
First page: 753
Abstract: With the in-depth research on hypersonic aerodynamics and hypersonic propulsion technology, humans are growing closer to space travel. Recent studies have shown that the pre-cooled air-turborocket (ATR) or turboexpander engines are some of the potential propulsion methods for reusable space vehicles and single stage-to-orbit (SSTO) missions because they have a high specific impulse at low Mach numbers, which can overcome the problem of the “thrust gap” in turbine-based combined-cycle (TBCC) engines. The ATR engine needs an additional oxidizing agent and the turboexpander engine usually uses hydrogen as fuel, which has low energy density and poor safety. To address this problem, this paper proposed a high-energy-density (HED) hydrocarbon-fueled turboexpander engine, and its feasibility has been proven through a simplified thermodynamic model. Through detailed thermodynamic analysis based on the energy and pressure balance, this paper analyzed the performance characteristics of the engine to evaluate its capacity to work in a wide speed range at low Mach numbers. The results show that the endothermic hydrocarbon-fueled turboexpander engine has good specific impulse in Mach 0∼4 at an equivalence ratio of 0.7∼1.3, and the turboexpander engine can be combined with the dual-mode scramjet and become an efficient acceleration method for SSTO missions and the reusable spacecraft.
Citation: Aerospace
PubDate: 2023-08-25
DOI: 10.3390/aerospace10090753
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 754: LoRa-Based Low-Cost Nanosatellite for
Emerging Communication Networks in Complex Scenarios
Authors: Raúl Parada, Victor Monzon Baeza, David N. Barraca-Ibort, Carlos Monzo
First page: 754
Abstract: Wireless broadband coverage has reached 95% worldwide. However, its trend is expected to stay the same in the following years, presenting challenges for scenarios such as remote villages and their surrounding environments. Inaccessibility to these areas for installing terrestrial base stations is the main challenge to bridge the connectivity gap. In addition, there are emergencies, for instance, earthquakes or war areas, that require a fast communication reaction by developing networks that are less susceptible to disruption. Therefore, we propose a low-cost, green-based nanosatellite system to provide complete coverage in hard-to-reach areas using long-range communication. The system comprises a pilot station, a base station, and a CubeSat with sensor data collector capabilities acting as a repeater. Our system can be built within hours with a 3D printer using common material, providing a flexible environment where components can be replaced freely according to user requirements, such as sensors and communication protocols. The experiments are performed in Spain by two test sets validating the communication among all components, with RSSI values below −148 dBm and the longest distance above 14 km. We highlight the reduction in the environmental impact of this proposal using a balloon-based launch platform that contributes to sustainable development.
Citation: Aerospace
PubDate: 2023-08-25
DOI: 10.3390/aerospace10090754
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 755: Coverage Path Planning Method for
Agricultural Spraying UAV in Arbitrary Polygon Area
Authors: Jiacheng Li, Hanlin Sheng, Jie Zhang, Haibo Zhang
First page: 755
Abstract: In the coverage path planning (CPP) problem of an agricultural spraying UAV, a margin reduction algorithm was designed first to address special situations such as ditches and channels within the operational terrain. Regarding the particularity of a concave polygon area, an algorithm based on topology mapping was developed to judge the concave points of the concave polygon area, and the path with special concave points was scheduled. For the evaluation of the pesticide spraying mission, the flight distance and extra coverage ratio were the most appropriate optimization objectives. Therefore, this paper selected these two indicators to form a fitness function, then found the optimal operating heading angle of the mission after iterative optimization. Finally, the CPP for an agricultural spraying UAV in an arbitrary polygon area under the optimal heading angle was realized. The simulation and flight test results showed that the CPP method could significantly shorten the flight distance and reduce additional coverage, then avoid energy consumption and pesticide waste. In addition, the engineering practicability of the method was verified in this paper. This method can be popularized and widely used for an agricultural spraying UAV, which has great engineering application value.
Citation: Aerospace
PubDate: 2023-08-25
DOI: 10.3390/aerospace10090755
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 756: Experiment and Numerical Simulation on
Damage Behavior of Honeycomb Sandwich Composites under Low-Energy Impact
Authors: Xiaoxia Zheng, Bohan He, Yu Zou, Qiao Yang, Yupeng Cao, Zhiqiang Li, Yaokun Han
First page: 756
Abstract: It is well-established that the honeycomb sandwich composite structures are easily prone to damage under low-energy impact. Consequently, it would lead to a dramatic decrease in structural load-bearing capacity and a threat to overall safety. Both experimental and numerical simulations are carried out to investigate the impact damage behavior of honeycomb sandwich composite specimens. The damage mode, damage parameters, and contact force-time curves of three types of panel materials with T300, T700, and T800 are obtained under different impact energies of 10 J, 20 J, and 40 J by the drop-weight impact experiment. Moreover, digital image correlation (DIC) tests are used to measure the deformation and strain of the lower panel. The experimental results reveal that the degree of damage increases with increasing impact energy. Particularly, the T300 panel specimen exhibits visible fiber fracture when subjected to an impact energy of 40 J. The impact process involves matrix cracking, fiber fracture, and delamination of the upper panel occurring first, followed by immediate crush damage to the honeycomb core and, finally, slight fiber damage to the lower panel. Due to its higher strength, the T800 panel specimen exhibits the highest damage resistance compared to the T700 and T300 panel specimens. To consider the microscopic failure criteria and various types of contact during the impact process, a finite element model of honeycomb sandwich composites is established, and numerical simulation analysis of low-energy impact is performed to determine the damage mode, damage size, and contact-force curves. Comparative analysis demonstrates good agreement between the simulation and experimental results. The findings of this study provide valuable technical support for the widespread application of honeycomb sandwich composites in the aviation field.
Citation: Aerospace
PubDate: 2023-08-27
DOI: 10.3390/aerospace10090756
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 757: Robust Controller Design for a Generic
Helicopter Model: An AI-Aided Application for Terrain Avoidance
Authors: Baris Baspinar
First page: 757
Abstract: This paper focuses on robust controller design for a generic helicopter model and terrain avoidance problem via artificial intelligence (AI). The helicopter model is presented as a hybrid system that covers hover and forward dynamics. By defining a set of easily accessible parameters, it can be used to simulate the motion of different helicopter types. A robust control structure based on reinforcement learning is proposed to ensure the system is robust against model parameter uncertainties. The developed generic model can be utilized in many helicopter applications that have been attempted to be solved with sampling-based algorithms or reinforcement learning approaches that take the dynamical constraints into consideration. This study also focuses on the helicopter terrain avoidance problem to illustrate how the model can be useful in these types of applications and provide an artificial intelligence-aided solution to terrain avoidance.
Citation: Aerospace
PubDate: 2023-08-27
DOI: 10.3390/aerospace10090757
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 758: Air Channel Planning Based on Improved Deep
Q-Learning and Artificial Potential Fields
Authors: Jie Li, Di Shen, Fuping Yu, Renmeng Zhang
First page: 758
Abstract: With the rapid advancement of unmanned aerial vehicle (UAV) technology, the widespread utilization of UAVs poses significant challenges to urban low-altitude safety and airspace management. In the coming future, the quantity of drones is expected to experience a substantial surge. Effectively regulating the flight behavior of UAVs has become an urgent and imperative issue that needs to be addressed. Hence, this paper proposes a standardized approach to UAV flight through the design of an air channel network. The air channel network comprises numerous single air channels, and this study focuses on investigating the characteristics of a single air channel. To achieve optimal outcomes, the concept of the artificial potential field algorithm is integrated into the deep Q-learning algorithm during the establishment of a single air channel. By improving the action space and reward mechanism, the resulting single air channel enables efficient avoidance of various buildings and obstacles. Finally, the algorithm is assessed through comprehensive simulation experiments, demonstrating its effective fulfillment of the aforementioned requirements.
Citation: Aerospace
PubDate: 2023-08-27
DOI: 10.3390/aerospace10090758
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 759: Combustion Characteristics of a
Swirl-Radial-Injection Composite Fuel Grain with Applications in Hybrid
Rockets
Authors: Ruoyan Wang, Xin Lin, Zezhong Wang, Kun Wu, Zelin Zhang, Jiaxiao Luo, Fei Li, Xilong Yu
First page: 759
Abstract: The combustion characteristics of a swirl-radial-injection composite fuel grain were experimentally and numerically investigated. This composite grain permits swirl-radial oxidizer injection based on three hollow helical blades, each having a constant hollow space allowing uniform oxidizer injection into the main chamber along the axial direction. The oxidizer enters from channel inlets located along a hollow outer wall. This wall, together with the three blades, is fabricated as one piece from acrylonitrile-butadiene-styrene using three-dimensional printing. Paraffin-based fuel is embedded in the spaces between adjacent blades. Firing tests were conducted with gaseous oxygen as the oxidizer, using oxidizer mass flow rates ranging from 7.45 to 30.68 g/s. Paraffin-based fuel grains using conventional fore-end injection were used for comparison. Regression rate boundaries were determined taking into account the erosion of the oxidizer channels. The data show that the regression rate was significantly increased even at the lower limit. Images of the combustion chamber flame and of the exhaust plume were also acquired. The flame was found to be concentrated in the main chamber and a smoky plume was observed, consistent with the high regression rate. A three-dimensional simulation was employed. The present design was found to improve fuel/oxidizer mixing and combustion efficiency compared with a fuel grain using fore-end injection. Both the experimental results and numerical simulations confirmed the potential of this swirl-radial-injection fuel grain.
Citation: Aerospace
PubDate: 2023-08-28
DOI: 10.3390/aerospace10090759
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 760: On the Size of the Safety Area around the
Launch Trajectory of a Rocket
Authors: Luiz M. B. C. Campos, Manuel J. S. Silva
First page: 760
Abstract: The safety zone around the flight path of a rocket is determined by the fall of debris in the case of an accidental explosion or commanded termination. The trajectory of a tumbling body in a vertical plane is determined by specifying the velocity, flight path angle and angle of attack as functions of time. This involves the lift, drag and pitching moment coefficients as functions of the angle of attack over a full circle—0 to 360 degrees—to account for the tumbling motion. The problem is reduced to a third-order non-linear differential equation for the angle of attack by using the approximation of free fall coordinates. The analytical and numerical solutions show that two types of tumbling fall are possible, one with rotation and the other with oscillation. The tumbling trajectories are plotted and discussed for a variety of initial conditions, mass and aerodynamic properties of the tumbling body.
Citation: Aerospace
PubDate: 2023-08-28
DOI: 10.3390/aerospace10090760
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 761: An Efficient Method for the Inverse Design
of Thin-Wall Stiffened Structure Based on the Machine Learning Technique
Authors: Yongtao Lyu, Yibiao Niu, Tao He, Limin Shu, Michael Zhuravkov, Shutao Zhou
First page: 761
Abstract: In this paper, a new method using the backpropagation (BP) neural network combined with the improved genetic algorithm (GA) is proposed for the inverse design of thin-walled reinforced structures. The BP neural network model is used to establish the mapping relationship between the input parameters (reinforcement type, rib height, rib width, skin thickness and rib number) and the output parameters (structural buckling load). A genetic algorithm is added to obtain the inversely designed result of a thin-wall stiffened structure according to the actual demand. In the end, according to the geometric parameters of inverse design, the thin-walled stiffened structure is reconstructed geometrically, and the numerical solutions of finite element calculation are compared with the target values of actual demand. The results show that the maximal inversely designed error is within 5.1%, which implies that the inverse design method of structural geometric parameters based on the machine learning and genetic algorithm is efficient and feasible.
Citation: Aerospace
PubDate: 2023-08-28
DOI: 10.3390/aerospace10090761
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 762: Condition-Based Maintenance in Aviation:
Challenges and Opportunities
Authors: Wim J. C. Verhagen, Bruno F. Santos, Floris Freeman, Paul van Kessel, Dimitrios Zarouchas, Theodoros Loutas, Richard C. K. Yeun, Iryna Heiets
First page: 762
Abstract: Condition-Based Maintenance (CBM) is a policy that uses information about the health condition of systems and structures to identify optimal maintenance interventions over time, increasing the efficiency of maintenance operations. Despite CBM being a well-established concept in academic research, the practical uptake in aviation needs to catch up to expectations. This research aims to identify challenges, limitations, solution directions, and policy implications related to adopting CBM in aviation. We use a generalizable and holistic assessment framework to achieve this aim, following a process-oriented view of CBM development as an aircraft lifecycle management policy. Based on various inputs from industry and academia, we identified several major sets of challenges and suggested three primary solution categories. These address data quantity and quality, CBM implementation, and the integration of CBM with future technologies, highlighting future research and practice directions.
Citation: Aerospace
PubDate: 2023-08-28
DOI: 10.3390/aerospace10090762
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 763: Investigation of Vaned-Recessed Casing
Authors: Mohammad Akhlaghi, Yahya Azizi
First page: 763
Abstract: In this paper, unsteady characteristics of a modified vaned-recessed casing treatment with 23.2% rotor blade tip axial chord exposure were studied numerically. The modifications to the traditional vaned-recessed casing treatments were composed of geometrical amendments to the casing treatment’s guide vanes and the top of the treated casing. The solid casing and the casing treatment configurations were simulated using the Unsteady Reynolds-Averaged Navier–Stokes equations (URANS), and the results were validated by experimental results. Firstly, standard deviation and frequency analysis were performed to find the sources of unsteadiness. Secondly, velocity components analysis, including velocity triangles, was presented instantaneously to clarify their effects on rotor tip flow fields as well as stall margin improvement. Thirdly, unsteady interactions between the rotor and casing treatment flow fields, including flow structure and pressure distributions, were discussed. In the end, flow streamline patterns, in addition to the physical mechanism of the vaned-recessed casing treatment, were also discussed. The results indicated that unsteadiness plays an important role in the flow mechanism and cannot be ignored. The unsteadiness increases as the mass flow is reduced toward the stall/surge condition. Moreover, the analysis of velocity components demonstrated that the casing treatment has distinct behavior at the last operating points before the onset of the stall for solid casing and casing treatment configurations in terms of axial velocity change.
Citation: Aerospace
PubDate: 2023-08-28
DOI: 10.3390/aerospace10090763
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 764: Investigation of Vaned-Recessed Casing
Treatment in a Low-Speed Axial Flow Compressor, Part I: Time-Averaged
Results
Authors: Mohammad Akhlaghi, Yahya Azizi
First page: 764
Abstract: This paper investigates the effects of two modifications to a vaned recessed casing treatment. First, the shape of a circular curve was used in the top of the treated casing. Second, a fully curved guide vane was also applied. The goals of the modifications are to enhance the flow recirculation as well as to relieve the low-speed flow, which is normally accumulated within the corners of the vaned recessed casing treatment. The solid casing in addition to the two vaned recessed configurations with 23.2% and 53.5% rotor blade tip axial chord exposure have been studied numerically. The results indicated that two mechanisms are involved in the stall margin enhancement. First, the circumferential pressure gradient is reduced for both configurations. The reduction in pressure gradient largely reduces the development of tip leakage vortex and, thus, the generation of low-speed fluid is diminished. Second, the main flow/tip leakage interface moves toward downstream and the movement of interface toward the leading edge is delayed. The second configuration with a greater rotor blade tip exposure enables extra flow recirculation due to decreasing surface area and, therefore, could be superior to the application of the first casing treatment configuration. The major streamlines within the casing treatment are also discussed. The time-averaged results are presented in this paper, while the unsteady results including instantaneous flow fields, origins of the unsteadiness and frequency analysis are discussed in part II.
Citation: Aerospace
PubDate: 2023-08-28
DOI: 10.3390/aerospace10090764
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 765: Integrated Design of Multi-Constrained
Snake Maneuver Surge Guidance Control for Hypersonic Vehicles in the Dive
Segment
Authors: Xiaojun Yu, Shibin Luo, Haiqiao Liu
First page: 765
Abstract: Focusing on the large maneuver penetration of the hypersonic glide vehicle with multiple constraints and uncertain disturbance, a robust integrated guidance and control law, which can achieve the snake-shape maneuver, is designed. A snake-shape maneuver acceleration command, in the framework of sine function, determined by the altitude, target declination of the line of sight and the missile-target distance, is discussed. The integrated guidance and control law includes the terminal guidance law with multiple constraints, attitude control law and angular velocity control law. In the terminal guidance law design, the sliding mode control is adopted while the adaptive technique is applied to estimate the disturbance. The selected sliding mode surface has variable gain determined by the estimated time-to-go. With the designed terminal guidance law, using the snake-shape maneuver acceleration command as the bias item, the angular rate of the line of sight will converge to zero and the line of sight angle will converge to the expected value, simultaneously. The attitude control law and angular velocity control law are designed to track the expected attack and bank angles. The stability of the whole system is proved with the application of the Lyapunov theorem. The effectiveness and robustness of the proposed integrated guidance and control law is verified by simulation.
Citation: Aerospace
PubDate: 2023-08-29
DOI: 10.3390/aerospace10090765
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 766: Numerical Investigation of Hypersonic
Flat-Plate Boundary Layer Transition Subjected to Bi-Frequency Synthetic
Jet
Authors: Xinyi Liu, Zhenbing Luo, Qiang Liu, Pan Cheng, Yan Zhou
First page: 766
Abstract: Transition delaying is of great importance for the drag and heat flux reduction of hypersonic flight vehicles. The first mode, with low frequency, and the second mode, with high frequency, exist simultaneously during the transition through the hypersonic boundary layer. This paper proposes a novel bi-frequency synthetic jet to suppress low- and high-frequency disturbances at the same time. Orthogonal table and variance analyses were used to compare the control effects of jets with different positions (USJ or DSJ), low frequencies (f1), high frequencies (f2), and amplitudes (a). Linear stability analysis results show that, in terms of the growth rate varying with the frequency of disturbance, an upstream synthetic jet (USJ) with a specific frequency and amplitude can hinder the growth of both the first and second modes, thereby delaying the transition. On the other hand, a downstream synthetic jet (DSJ), regardless of other parameters, increases flow instability and accelerates the transition, with higher frequencies and amplitudes resulting in greater growth rates for both modes. Low frequencies had a significant effect on the first mode, but a weak effect on the second mode, whereas high frequencies demonstrated a favorable impact on both the first and second modes. In terms of the growth rate varying with the spanwise wave number, the control rule of the same parameter under different spanwise wave numbers was different, resulting in a complex pattern. In order to obtain the optimal delay effect upon transition and improve the stability of the flow, the parameters of the bi-synthetic jet should be selected as follows: position it upstream, with f1 = 3.56 kHz, f2 = 89.9 kHz, a = 0.009, so that the maximum growth rate of the first mode is reduced by 9.06% and that of the second mode is reduced by 1.28% compared with the uncontrolled state, where flow field analysis revealed a weakening of the twin lattice structure of pressure pulsation.
Citation: Aerospace
PubDate: 2023-08-29
DOI: 10.3390/aerospace10090766
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 767: A Phenomenological Model for the Unsteady
Combustion of Solid Propellants from a Zel’dovich-Novzhilov Approach
Authors: Zhuopu Wang, Wenchao Zhang, Yuanzhe Liu
First page: 767
Abstract: Solid rocket motors are prone to combustion instabilities, which may lead to various problems for the rockets, from unexpected oscillations, precision decreasing, to explosion. The unsteady combustion dynamics of the propellants play a crucial role in most solid rocket motors experiencing combustion instabilities. A modeling framework for the unsteady combustion of the solid propellant is constructed via the Zel’dovich-Novozhilov (ZN) phenomenological perspective. The overall unsteady combustion features of a quasi-steady homogeneous one-dimensional (QSHOD) model are investigated. The phenomenological ZN parameters are then calculated. Compared with the traditional ZN-QSHOD linear equivalence relation, the new calculated system yields better results for the pressure coupling response, especially in the non-linear regime. The proposed phenomenological modeling provides a new methodology for the model reduction of the complex flame models.
Citation: Aerospace
PubDate: 2023-08-29
DOI: 10.3390/aerospace10090767
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 768: Distributed Adaptive Path-Following Control
for Distance-Based Formation of Fixed-Wing UAVs under Input Saturation
Authors: Junfeng Wu, Huan Wang, Shanshan Li, Shuguang Liu
First page: 768
Abstract: This paper investigates the distance-based formation and cooperative path-following control problems for multiple fixed-wing unmanned aerial vehicles (UAVs). In this study, we design the distance-based formation control structure to achieve the virtual leader and followers pre-defined rigid formation pattern, ensuring simultaneously relative localization. A path-following control strategy based on adaptive dynamic surface and neural network control technology is proposed to approximate the uncertain disturbances of the environment and unmodeled dynamics. And the longitudinal and lateral subsystems’ adaptive fault-tolerant controllers are designed, respectively, to achieve the fault-tolerant control of UAVs’ formation in three-dimensional environments. Furthermore, the adaptive sliding mode controller with an auxiliary controller is designed to realize the UAVs path following with limited input saturation. Finally, simulation examples are given to clarify and verify the effectiveness of the theoretical results.
Citation: Aerospace
PubDate: 2023-08-30
DOI: 10.3390/aerospace10090768
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 769: A Full Envelope Robust Linear
Parameter-Varying Control Method for Aircraft Engines
Authors: Bin Shen, Lingfei Xiao, Zhifeng Ye
First page: 769
Abstract: In order to solve the problem of full flight envelope control for aircraft engines, the design of a linear parameter-varying (LPV) controller is described in this paper. First, according to the nonlinear aerodynamic model of the aircraft engine, the LPV engine model for the controller design is obtained through the Jacobian linearization and fitting technique. Then, the flight envelope is divided into several sub-regions, and the intersection of adjacent sub-regions is not empty. The sub-region LPV controller is designed using the parameter-dependent Lyapunov function (PDLF)-based LPV synthesis method, while eliminating the dependence of the LPV controller on scheduling parameter derivatives. In order to ensure the stability and performance of the aircraft engine across the full flight envelope, a mixing LPV control method is proposed to design the LPV controller in the overall region. The effectiveness of the proposed method is verified by simulating a dual-spool turbofan engine on a nonlinear component level model and comparing the proposed method with the gain scheduling based on PI and H∞ point design.
Citation: Aerospace
PubDate: 2023-08-31
DOI: 10.3390/aerospace10090769
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 770: Examining the Potential of Generative
Language Models for Aviation Safety Analysis: Case Study and Insights
Using the Aviation Safety Reporting System (ASRS)
Authors: Archana Tikayat Ray, Anirudh Prabhakara Bhat, Ryan T. White, Van Minh Nguyen, Olivia J. Pinon Fischer, Dimitri N. Mavris
First page: 770
Abstract: This research investigates the potential application of generative language models, especially ChatGPT, in aviation safety analysis as a means to enhance the efficiency of safety analyses and accelerate the time it takes to process incident reports. In particular, ChatGPT was leveraged to generate incident synopses from narratives, which were subsequently compared with ground-truth synopses from the Aviation Safety Reporting System (ASRS) dataset. The comparison was facilitated by using embeddings from Large Language Models (LLMs), with aeroBERT demonstrating the highest similarity due to its aerospace-specific fine-tuning. A positive correlation was observed between the synopsis length and its cosine similarity. In a subsequent phase, human factors issues involved in incidents, as identified by ChatGPT, were compared to human factors issues identified by safety analysts. The precision was found to be 0.61, with ChatGPT demonstrating a cautious approach toward attributing human factors issues. Finally, the model was utilized to execute an evaluation of accountability. As no dedicated ground-truth column existed for this task, a manual evaluation was conducted to compare the quality of outputs provided by ChatGPT to the ground truths provided by safety analysts. This study discusses the advantages and pitfalls of generative language models in the context of aviation safety analysis and proposes a human-in-the-loop system to ensure responsible and effective utilization of such models, leading to continuous improvement and fostering a collaborative approach in the aviation safety domain.
Citation: Aerospace
PubDate: 2023-08-31
DOI: 10.3390/aerospace10090770
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 771: Application of a Psychosocial Approach to
the Identification and Strengthening of Adaptation Mechanisms of Humans
and a Small Social Group during the Isolation Experiment “SIRIUS
2017–2023”
Authors: Katerina Bernardova Sykorova
First page: 771
Abstract: TOPIC: The task of the 21st century is the implementation of manned flights in Earth’s orbit with the view to building orbital and planetary bases. This requires addressing the impacts on people and small social groups in terms of psychological, psychosocial, physiological and health. The author presents her own comprehensive research and intervention approach to exploring and supporting the operation of the space crew in the four-month isolation period of “SIRIUS-18/19”, which can be used in the future for manned flights into deep space. GOAL: The main goal is to present three main areas, within the implementation of social research, designed to analyze the operation of the crew in a simulated space flight: 1. WORKING CONDITIONS, WORKING ENVIRONMENT AND SOCIAL ATMOSPHERE; 2. the STRUCTURE AND DYNAMICS OF RELATIONSHIPS and TIES; 3. a set of other specific areas. The key outputs of the comprehensive analysis of the “SIRIUS-19” crew operations concerning the level of satisfaction with the working environment and conditions, the structure and dynamics of relationships and other specific areas are presented. The suitability of the implementation of intervention activities for isolated crews is pointed out. The purpose is to contribute to the preparation of human crews for manned flights in deep space and to reduce the risks of damage to human biopsychosocial health. METHODS: For a comprehensive analysis, a set of the author’s own questionnaire methods, verified over 25 years in the normal and extremely demanding conditions of specific professions, was used. The diagnostic and intervention method sociomapping, based on fuzzy theory and the mathematical modeling of outputs, was used for the analysis of the structure and dynamics of relationships as it is a technique suitable for the analysis of nonlinear dynamical systems. The methodology enabled the author to obtain a comprehensive view of the experimental situation from a psychosocial and sociological point of view. RESULTS: The model of the author’s analytical approach confirmed the legitimacy of its implementation in the case of isolation experiments. A comprehensive analysis of the “SIRIUS-18/19” crew’s work environment yielded outputs from the 10 main and 48 sub-areas analyzed. The analysis of the six-member, gender-mixed, multicultural crew in the area of structure and dynamics of relationships focused on 35 areas; a total of 344 sociomaps were created. The files were analyzed qualitatively and quantitatively using control diagrams. CONCLUSIONS: Outputs have the potential to be used in other isolation experiments as sociotechnical measures for project organizers and as verification of the need to introduce work with the crew in the form of development workshops using the sociomapping method.
Citation: Aerospace
PubDate: 2023-08-31
DOI: 10.3390/aerospace10090771
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 772: A Methodology for Allocating Incremental
Resources in Single-Airport Time Slots
Authors: Shuce Wang, Minghua Hu, Zhening Chang, Xuhao Zhu
First page: 772
Abstract: Air carriers shall not readily relinquish their held flight slots. In cases where the historical flight slot pool cannot be easily altered, a pressing need arises for an allocation method that can efficiently utilize the incremental resources of these time slots. This paper presents an integer planning model to address the efficient allocation of incremental airport time slot resources. The model considers the capacity of key resource nodes and flight waveforms as constraints to maximize the total incremental slots. Moreover, it considers the adaptation of strategic and tactical optimization. After conducting a case study using Beijing Capital International Airport for verification, the proposed model effectively reduces potential operational delays by 66.27% while adding 366 to 397-time slots. Notably, the model demonstrates remarkable delay reduction capabilities and can serve as a valuable decision-support tool for the incremental allocation of time slots.
Citation: Aerospace
PubDate: 2023-08-31
DOI: 10.3390/aerospace10090772
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 773: Installed Fan Noise Simulation of a
Supersonic Business Aircraft
Authors: Stan Proskurov, Markus Lummer, Jan Werner Delfs, Roland Ewert, Jochen Kirz, Martin Plohr, Robert Jaron
First page: 773
Abstract: Overcoming the problem of excessive engine noise at low altitudes is a formidable task on the way to developing a supersonic passenger aircraft. The focus of this paper is on the fan noise shielding during take-off, investigated as part of the DLR project ELTON SST (estimation of landing and take-off noise of supersonic transport) for an in-house aircraft design. The supersonic inlet is required to provide the proper quantity and uniformity of air to the engine over a wider range of flight conditions than the subsonic inlet. For passenger aircraft, the noise problem influences engine integration and placement, and the new generation of supersonic transport would require innovative engineering solutions in order to come up with an efficient low-noise design. Potential solutions are evaluated using DLR tools capable of accurate source generation and noise propagation to the far-field. For low-speed aircraft operation, the method of choice is a strongly coupled volume-resolving discontinuous Galerkin (DG) and fast multipole boundary element method (FM-BEM) which is applied due to a large disparity between the Mach numbers on the interior and exterior of the inlet. The method is used for obtaining the acoustic signature of the full-scale model at realistic flight points, including the application of the programmed lapse rate (PLR), which involves simulations at higher pitch angles than for the reference flight path. The results show that the proposed method is highly suitable for obtaining accurate noise footprints during the low-speed phase and could be used to assist with certification procedures of future supersonic aircraft.
Citation: Aerospace
PubDate: 2023-08-31
DOI: 10.3390/aerospace10090773
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 774: Lightweight Design for Active Small
Synthetic Aperture Radar (SAR) Small SAR Technology Experimental Project
Satellite Using Multilayered High-Damping Carbon Fiber-Reinforced
Plastic-Based Patch
Authors: Kyung-Rae Koo, Hyun-Guk Kim, Dong-Geon Kim, Seong-Cheol Kwon, Hyun-Ung Oh
First page: 774
Abstract: In the launch environment, satellites are subjected to severe dynamic loads. These dynamic loads in the launch environment can lead to the malfunction of the payload, or to mission failure. In order to improve the structural stability of satellites and enable the reliable execution of space missions, it is necessary to have a reinforcement structure that reduces structural vibrations. However, for active small SAR satellites, the mass requirements are very strict, and this makes it difficult to apply an additional structure for vibration reduction. Therefore, we have developed a carbon fiber-reinforced plastic (CFRP)-based laminated patch to obtain a vibration reduction structure with a lightweight design for improving the structural stability of an S-STEP satellite. To verify the vibration reduction performance of the CFRP-based patch, sine and random vibration tests were conducted at the specimen level. Finally, the structural stability of the S-STEP satellite with the proposed CFRP-based laminated patch was experimentally verified using sine and random vibration tests. The validation results indicate that the CFRP-based laminated patch is an efficient solution which can effectively reduce the vibration response without the need for major changes to the design of the satellite structure. The lightweight vibration reduction mechanism developed in this study is one of the best solutions for protecting vibration-sensitive components.
Citation: Aerospace
PubDate: 2023-08-31
DOI: 10.3390/aerospace10090774
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 775: AMU-LED Cranfield Flight Trials for
Demonstrating the Advanced Air Mobility Concept
Authors: Arinc Tutku Altun, Mehmet Hasanzade, Emre Saldiran, Guney Guner, Mevlut Uzun, Rodolphe Fremond, Yiwen Tang, Prithiviraj Bhundoo, Yu Su, Yan Xu, Gokhan Inalhan, Michael W. Hardt, Alejandro Fransoy, Ajay Modha, Jose Antonio Tena, Cesar Nieto, Miguel Vilaplana, Marta Tojal, Victor Gordo, Pablo Menendez, Ana Gonzalez
First page: 775
Abstract: Advanced Air Mobility (AAM) is a concept that is expected to transform the current air transportation system and provide more flexibility, agility, and accessibility by extending the operations to urban environments. This study focuses on flight test, integration, and analysis considerations for the feasibility of the future AAM concept and showcases the outputs of the Air Mobility Urban-Large Experimental Demonstration (AMU-LED) project demonstrations at Cranfield University. The purpose of the Cranfield demonstrations is to explore the integrated decentralized architecture of the AAM concept with layered airspace structure through various use cases within a co-simulation environment consisting of real and simulated standard-performing vehicle (SPV) and high-performing vehicle (HPV) flights, manned, and general aviation flights. Throughout the real and simulated flights, advanced U-space services are demonstrated and contingency management activities, including emergency operations and landing, are tested within the developed co-simulation environment. Moreover, flight tests are verified and validated through key performance indicator analysis, along with a social acceptance study. Future recommendations on relevant industrial and regulative activities are provided.
Citation: Aerospace
PubDate: 2023-08-31
DOI: 10.3390/aerospace10090775
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 776: A Study on Influence of Flapping Dynamic
Characteristics on Vibration Control of Active Rotor with Trailing-Edge
Flaps
Authors: Gu, Dong, Li, Yang
First page: 776
Abstract: An active rotor with trailing-edge flaps (TEFs) is an effective active vibration control method for helicopters. Blade flapping dynamic characteristics have a significant effect on the active vibration control performance of an active rotor. In this study, an aeroelastic model is developed using the Hamilton principle, and a quasi-steady Theodorsen model for the airfoil with a TEF is utilized to calculate the aerodynamic loads induced by the dynamic deflection of TEFs. The accuracy of this model is validated through a comparison with the CAMRAD calculation and flight test results of a SA349/2 helicopter. Based on the modal orthogonality and the equilibrium equation of the blade flapping motion, the method of changing the blade flapping dynamic characteristics is obtained. Blade sectional characteristics are adjusted to study the effect of blade flapping dynamics on the vibration control authority of an active rotor. The simulation results demonstrate that if the modal frequency of second-order flap is tuned to close to the rotor passage frequency, the flapping dynamic characteristics are capable of enhancing the vibration control performance of the active rotor.
Citation: Aerospace
PubDate: 2023-08-31
DOI: 10.3390/aerospace10090776
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 777: Adaptive Neural Network Global Fractional
Order Fast Terminal Sliding Mode Model-Free Intelligent PID Control for
Hypersonic Vehicle’s Ground Thermal Environment
Authors: Xiaodong Lv, Guangming Zhang, Zhiqing Bai, Xiaoxiong Zhou, Zhihan Shi, Mingxiang Zhu
First page: 777
Abstract: In this paper, an adaptive neural network global fractional order fast terminal sliding mode model-free intelligent PID control strategy (termed as TDE-ANNGFOFTSMC-MFIPIDC) is proposed for the hypersonic vehicle ground thermal environment simulation test device (GTESTD). Firstly, the mathematical model of the GTESTD is transformed into an ultra-local model to ensure that the control strategy design process does not rely on the potentially inaccurate dynamic GTESTD model. Meanwhile, time delay estimation (TDE) is employed to estimate the unknown terms of the ultra-local model. Next, a global fractional-order fast terminal sliding mode surface (GFOFTSMS) is introduced to effectively reduce the estimation error generated by TDE. It also eliminates arrival time, accelerates the convergence speed of the sliding phase, guarantees finite time arrival, avoids the singularity phenomenon, and bolsters robustness. Then, as the upper bound of the disturbance error is unknown, an adaptive neural network (ANN) control is designed to approximate the upper bound of the estimation error closely and mitigate the chattering phenomenon. Furthermore, the stability of the control system and the convergence time are proven by the Lyapunov stability theorem and are calculated, respectively. Finally, simulation results are conducted to validate the efficacy of the proposed control strategy.
Citation: Aerospace
PubDate: 2023-08-31
DOI: 10.3390/aerospace10090777
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 778: Space Manipulator Collision Avoidance Using
a Deep Reinforcement Learning Control
Authors: James Blaise, Michael C. F. Bazzocchi
First page: 778
Abstract: Recent efforts in on-orbit servicing, manufacturing, and debris removal have accentuated some of the challenges related to close-proximity space manipulation. Orbital debris threatens future space endeavors driving active removal missions. Additionally, refueling missions have become increasingly viable to prolong satellite life and mitigate future debris generation. The ability to capture cooperative and non-cooperative spacecraft is an essential step for refueling or removal missions. In close-proximity capture, collision avoidance remains a challenge during trajectory planning for space manipulators. In this research, a deep reinforcement learning control approach is applied to a three-degrees-of-freedom manipulator to capture space objects and avoid collisions. This approach is investigated in both free-flying and free-floating scenarios, where the target object is either cooperative or non-cooperative. A deep reinforcement learning controller is trained for each scenario to effectively reach a target capture location on a simulated spacecraft model while avoiding collisions. Collisions between the base spacecraft and the target spacecraft are avoided in the planned manipulator trajectories. The trained model is tested for each scenario and the results for the manipulator and base motion are detailed and discussed.
Citation: Aerospace
PubDate: 2023-08-31
DOI: 10.3390/aerospace10090778
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 779: Energy Analysis for Solar-Powered Unmanned
Aerial Vehicle under Static Soaring
Authors: Yansen Wu, Ke Li, Anmin Zhao, Haobo Liu, Yuangan Li, Dongsheng Wen
First page: 779
Abstract: Endurance is a critical factor for solar-powered unmanned aerial vehicles (SUAVs). Taking inspiration from birds, SUAVs have the ability to harvest extra energy from atmospheric thermal updrafts to extend their endurance. Though recent research has mainly focused on estimating the characteristics of thermal updrafts, there is a noticeable dearth of studies investigating the energy performance of SUAVs during soaring under different conditions. To begin with, this work establishes a thermal updraft and SUAV energy model. In addition, it introduces an integrated guidance and control process to achieve static soaring within thermal for SUAVs. Numerical simulations are implemented to analyze the electric energy performance at different solar irradiation levels, SUAV velocities and thermal strengths. Several remarkable conclusions are drawn from the simulations, which could provide significant insights for SUAVs to further exploit thermal energy.
Citation: Aerospace
PubDate: 2023-08-31
DOI: 10.3390/aerospace10090779
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 780: Discretization Method to Improve the
Efficiency of Complex Airspace Operation
Authors: Daiwu Zhu, Zehui Chen, Xiaofan Xie, Jiuhao Chen
First page: 780
Abstract: With the increase in airspace flow, the complexity of the airspace operation environment has also increased. Against this backdrop, improving the operational efficiency of airspace is crucial to ensure its efficient operation. The discrete division of controlled airspace represents a novel methodology for achieving this end. This approach involves visualizing the use of the airspace, quantifying and evaluating the operational efficiencies of airspace environments, and assessing specific metrics during an allocated time period. In this study, a discrete unit model was constructed to hierarchically subdivide complex airspace into static obstacles and aircraft-occupied space units, which facilitated the optimization of decision-making operations for multiple aircraft in airspace using the discrete method. Furthermore, busy airspace units could be effectively avoided. Finally, by using the extended analytic hierarchy process, we evaluated the threshold value of airspace operational efficiency improvement when operation efficiency metrics were enhanced via discrete approaches. The results indicated that the threshold value was 0.02168, classified as “good”, which represented an improvement in comparison with the original value of airspace operational efficiency (0.03173). These findings demonstrated that the application of the discrete division methodology significantly improved the overall operational efficiency of the airspace.
Citation: Aerospace
PubDate: 2023-09-01
DOI: 10.3390/aerospace10090780
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 781: Risk Assessment Method for UAV’s
Sense and Avoid System Based on Multi-Parameter Quantification and Monte
Carlo Simulation
Authors: Bona P. Fitrikananda, Yazdi Ibrahim Jenie, Rianto Adhy Sasongko, Hari Muhammad
First page: 781
Abstract: The rise in Unmanned Aerial Vehicle (UAV) usage has opened exciting possibilities but has also introduced risks, particularly in aviation, with instances of UAVs flying dangerously close to commercial airplanes. The potential for accidents underscores the urgent need for effective measures to mitigate mid-air collision risks. This research aims to assess the effectiveness of the Sense and Avoid (SAA) system during operation by providing a rating system to quantify its parameters and operational risk, ultimately enabling authorities, developers, and operators to make informed decisions to reach a certain level of safety. Seven parameters are quantified in this research: the SAA’s detection range, field of view, sensor accuracy, measurement rate, system integration, and the intruder’s range and closing speed. While prior studies have addressed these parameter quantifications separately, this research’s main contribution is the comprehensive method that integrates them all within a simple five-level risk rating system. This quantification is complemented by a risk assessment simulator capable of testing a UAV’s risk rating within a large sample of arbitrary flight traffic in a Monte Carlo simulation setup, which ultimately derives its maximum risk rating. The simulation results demonstrated safety improvements using the SAA system, shown by the combined maximum risk rating value. Among the contributing factors, the detection range and sensor accuracy of the SAA system stand out as the primary drivers of this improvement. This conclusion is consistent even in more regulated air traffic imposed with five or three mandatory routes. Interestingly, increasing the number of intruders to 50 does not alter the results, as the intruders’ probability of being detected remains almost the same. On the other hand, improving SAA radar capability has a more significant effect on risk rating than enforcing regulations or limiting intruders.
Citation: Aerospace
PubDate: 2023-09-01
DOI: 10.3390/aerospace10090781
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 782: Power Balance Strategies in Steady-State
Simulation of the Micro Gas Turbine Engine by Component-Coupled 3D CFD
Method
Authors: Yibing Xu, Lei Gao, Ruizhe Cao, Chong Yan, Ying Piao
First page: 782
Abstract: Currently, an increasing number of designers have begun to pay attention to a new paradigm for evaluating the performance with full engine 3-dimensional computational fluid dynamics (3D CFD) simulations. Compared with the traditional component-based performance simulation method component-based performance simulation method (‘component-matched’ method), this novel ‘component-coupled’ method can evaluate the overall performance of the engine more physically and obtain more detailed flow field parameters simultaneously. Importantly, the power balance iteration should be introduced to the novel method to satisfy the constraints of the coaxial components for the gas turbine engine at steady state. By carrying out the ‘component-matched’ simulation and the ‘component-coupled’ simulation for a micro turbojet engine, the necessity of introducing the power balance iteration was discussed in this paper. The influence of steady-state co-working constraints on the engine performance was analysed and strategies for power balance iteration were proposed. To verify the capability and feasibility of this method, not only the co-working state but also the windmill state of the gas turbine engine were simulated by using the 3D CFD method considering power balance iteration. The results show that the power balance strategy proposed in this paper can converge the aerodynamic parameters as well as the power residual in a robust way.
Citation: Aerospace
PubDate: 2023-09-04
DOI: 10.3390/aerospace10090782
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 783: Intelligent Maneuver Strategy for a
Hypersonic Pursuit-Evasion Game Based on Deep Reinforcement Learning
Authors: Yunhe Guo, Zijian Jiang, Hanqiao Huang, Hongjia Fan, Weiye Weng
First page: 783
Abstract: In order to improve the problem of overly relying on situational information, high computational power requirements, and weak adaptability of traditional maneuver methods used by hypersonic vehicles (HV), an intelligent maneuver strategy combining deep reinforcement learning (DRL) and deep neural network (DNN) is proposed to solve the hypersonic pursuit–evasion (PE) game problem under tough head-on situations. The twin delayed deep deterministic (TD3) gradient strategy algorithm is utilized to explore potential maneuver instructions, the DNN is used to fit to broaden application scenarios, and the intelligent maneuver strategy is generated with the initial situation of both the pursuit and evasion sides as the input and the maneuver game overload of the HV as the output. In addition, the experience pool classification strategy is proposed to improve the training convergence and rate of the TD3 algorithm. A set of reward functions is designed to achieve adaptive adjustment of evasion miss distance and energy consumption under different initial situations. The simulation results verify the feasibility and effectiveness of the above intelligent maneuver strategy in dealing with the PE game problem of HV under difficult situations, and the proposed improvement strategies are validated as well.
Citation: Aerospace
PubDate: 2023-09-04
DOI: 10.3390/aerospace10090783
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 784: Numerical Simulation of Transonic
Compressors with Different Turbulence Models
Authors: Wenhui Yan, Zhaozheng Sun, Junwei Zhou, Kun Zhang, Jiahui Wang, Xiao Tian, Junqian Tian
First page: 784
Abstract: One of the most commonly used techniques in aerospace engineering is the RANS (Reynolds average Navier–Stokes) approach for calculating the transonic compressor flow field, where the accuracy of the computation is significantly affected by the turbulence model used. In this work, we use SA, SST, k-ɛ, and the PAFV turbulence model developed based on the side-biased mean fluctuations velocity and the mean strain rate tensor to numerically simulate the transonic compressor NASA Rotor 67 to evaluate the accuracy of turbulence modeling in numerical calculations of transonic compressors. The simulation results demonstrate that the four turbulence models are generally superior in the numerical computation of NASA Rotor 67, which essentially satisfies the requirements of the accuracy of engineering calculations; by comparing and analyzing the ability of the four turbulence models to predict the aerodynamic performance of transonic compressors and to capture the details of the flow inside the rotor. The errors of the Rotor 67 clogging flow rate calculated by the SA, SST, k-ɛ, and PAFV turbulence models with the experimental data are 0.9%, 0.8%, 0.7%, and 0.6%, respectively. The errors of the calculated peak efficiencies are 2.2%, 1.6%, 0.9%, and 4.9%. The SA and SST turbulence models were developed for the computational characteristics of the aerospace industry. Their computational stability is better and their outputs for Rotor 67 are comparable. The k-ɛ turbulence model calculates the pressure ratio and efficiency that are closest to the experimental data, but the computation of its details of the flow field near the wall surface is not ideal because the k-ɛ turbulence model cannot accurately capture the flow characteristics of the region of high shear stresses. The PAFV turbulence model has a better prediction of complex phenomena such as rotor internal shock wave location, shock–boundary layer interaction, etc., due to the use of a turbulent velocity scale in vector form, but the calculated rotor efficiency is small.
Citation: Aerospace
PubDate: 2023-09-06
DOI: 10.3390/aerospace10090784
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 785: Fatigue Reliability Analysis of Composite
Material Considering the Growth of Effective Stress and Critical Stiffness
Authors: Jian-Xiong Gao, Fei Heng, Yi-Ping Yuan, Yuan-Yuan Liu
First page: 785
Abstract: Fatigue damage accumulation will not only cause the degradation of material performance but also lead to the growth of effective stress and critical stiffness. However, the existing fatigue reliability models usually ignore the effective stress growth and its influence on the critical stiffness of a composite material. This study considers the combined effects of performance degradation and effective stress growth, and a pair of fatigue reliability models for a composite material are presented. Firstly, the fatigue damage in a composite material is quantified by its performance degradation, and the fitting accuracy of several typical fatigue damage models is compared. Subsequently, the uncertainties of initial strength and initial stiffness are considered, and a pair of probabilistic models of residual strength and residual stiffness are proposed. The performance degradation data of Gr/PEEK [0/45/90/−45]2S laminates are utilized to verify the proposed probabilistic models. Finally, the effective stress growth mechanism and its influence on the failure threshold are elaborated, and a pair of fatigue reliability models for composite materials are developed. Moreover, the differences between the strength-based and stiffness-based reliability analysis results of composite materials are compared and discussed.
Citation: Aerospace
PubDate: 2023-09-06
DOI: 10.3390/aerospace10090785
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 786: L1 Adaptive Control Based on Dynamic
Inversion for Morphing Aircraft
Authors: Lingquan Cheng, Yiyang Li, Jiayi Yuan, Jianliang Ai, Yiqun Dong
First page: 786
Abstract: Morphing aircraft are able to keep optimal performance in diverse flight conditions. However, the change in geometry always leads to challenges in the design of flight controllers. In this paper, a new method for designing a flight controller for variable-sweep morphing aircraft is presented—dynamic inversion combined with L1 adaptive control. Firstly, the dynamics of the vehicle is analyzed and a six degrees of freedom (6DOF) nonlinear dynamics model based on multibody dynamics theory is established. Secondly, nonlinear dynamic inversion (NDI) and incremental nonlinear dynamic inversion (INDI) are then employed to realize decoupling control. Thirdly, linear quadratic regulator (LQR) technique and L1 adaptive control are adopted to design the adaptive controller in order to improve robustness to uncertainties and ensure the control accuracy. Finally, extensive simulation experiments are performed, wherein the demonstrated results indicate that the proposed method overcomes the drawbacks of conventional methods and realizes an improvement in control performance.
Citation: Aerospace
PubDate: 2023-09-07
DOI: 10.3390/aerospace10090786
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 787: Progress in Redundant Electromechanical
Actuators for Aerospace Applications
Authors: Fawaz Yahya Annaz, Malaka Miyuranga Kaluarachchi
First page: 787
Abstract: The power to move aircraft control surfaces has advanced from being manually generated (by the pilot and transmitted via rods and links) to electrically transmitted (via wires) to operate control surface actuators. Various hydraulic, electromagnetic, and electromechanical architectures have been developed to provide the necessary power and to maintain the expected redundancy. Numerous aircraft actuator system designs have been proposed in the past decades, but a comprehensive review has yet to be undertaken. This review paper aims to fill this gap by providing a critical review of the actuation system designs developed for a variety of aircraft. The review focuses on aircraft actuator system designs, namely: electrohydraulic actuator systems, electromechanical actuator systems, and the force-fighting effect in redundant actuation systems. The significance and operational principle of each actuator system are critically analysed and discussed in the review. The paper also evaluates the solution proposed to address force-fight equalization (or force-fight cancelation) in force or torqued-summed architectures. Future trends in redundant actuation system development with reduced force-fighting effect in aircraft actuator systems are also addressed.
Citation: Aerospace
PubDate: 2023-09-07
DOI: 10.3390/aerospace10090787
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 788: A Digital-Twin-Based Detection and
Protection Framework for SDC-Induced Sinkhole and Grayhole Nodes in
Satellite Networks
Authors: Gongzhe Qiao, Yi Zhuang, Tong Ye, Yuan Qiao
First page: 788
Abstract: In the space environment, cosmic rays and high-energy particles may cause a single-event upset (SEU) during program execution, and further cause silent data corruption (SDC) errors in program outputs. After extensive research on SEU and SDC errors, it has been found that SDC errors in the routing program in satellite networks may lead to the emergence of Sinkhole (SH) and Grayhole (GH) nodes in the network, which may cause damage to satellite networks. To find and solve the problems in time, a digital-twin-based detection and protection framework for SDC-induced SH and GH nodes in satellite networks is proposed. First, the satellite network fault model under SEU and the generation mechanism of SH and GH nodes induced by SDC errors are described. Then, the data structure based on digital twins required by the proposed detection and protection framework is designed, and the detection methods of SH and GH nodes induced by SDC errors are proposed. SKT and LLFI simulation tools are used to build a simulated Iridium satellite network and carry out fault injection experiments. Experiment results show that the accuracy of the proposed detection method is 98–100%, and the additional time cost of routing convergence caused by the proposed framework is 3.1–28.2%. Compared with existing SH and GH detection methods, the proposed methods can timely and accurately detect faults during the routing update stage.
Citation: Aerospace
PubDate: 2023-09-07
DOI: 10.3390/aerospace10090788
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 789: A Novel Digital Twin Framework for
Aeroengine Performance Diagnosis
Authors: Zepeng Wang, Ye Wang, Xizhen Wang, Kaiqiang Yang, Yongjun Zhao
First page: 789
Abstract: Aeroengine performance diagnosis technology is essential for ensuring flight safety and reliability. The complexity of engine performance and the strong coupling of fault characteristics make it challenging to develop accurate and efficient gas path diagnosis methods. To address these issues, this study proposes a novel digital twin framework for aeroengines that achieves the digitalization of physical systems. The mechanism model is constructed at the component level. The data-driven model is built using a particle swarm optimization–extreme gradient boosting algorithm (PSO-XGBoost). These two models are fused using the low-rank multimodal fusion method (LWF) and combined with the sparse stacked autoencoder (SSAE) to form a digital twin framework of the engine for performance diagnosis. Compared to methods that are solely based on mechanism or data, the proposed digital twin framework can effectively use mechanism and data information to improve the accuracy and reliability. The research results show that the proposed digital twin framework has an error rate of 0.125% in predicting gas path parameters and has a gas path fault diagnosis accuracy of 98.6%. Considering that the degradation cost of a typical flight mission for only one aircraft engine after 3000 flight cycles is approximately USD 209.5, the proposed method has good economic efficiency. This framework can be used to improve engine reliability, availability, and efficiency, and has significant value in engineering applications.
Citation: Aerospace
PubDate: 2023-09-08
DOI: 10.3390/aerospace10090789
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 790: Characteristics of Vortices around Forward
Swept Wing at Low Speeds/High Angles of Attack
Authors: Masahiro Kanazaki, Nao Setoguchi
First page: 790
Abstract: The forward-swept wing (FSW), one of the wing planforms used in aircraft, is known for its high performance in reducing wave drag. Additionally, a study has shown that this wing planform can mitigate sonic booms, which pose a significant challenge to achieving supersonic transport (SST). Therefore, FSW is expected to find applications in future SST aircraft owing to aerodynamic advantages at high speeds. However, there is a lack of sufficient knowledge and systematization to improve aerodynamic performance at low speeds and high angles of attack during takeoff and landing. These are crucial for practical implementation. Although the aerodynamic benefits of an FSW in high-speed flight can be harnessed using advanced structural and control technologies, the realization of SST using an FSW is challenging without enhanced research on low-speed aerodynamics. This study explores the practical aerodynamic knowledge of FSWs. We utilized a numerical simulation based on the Navier–Stokes equation and focused on investigating wake vortex phenomena. Our simulation included various wing planforms, including backward-swept wings (BSWs). The results revealed the presence of vortices with lateral axes emanating from the FSW, while longitudinal vortices were observed in the BSW. Based on these results, we developed a theoretical hypothesis for the vortex structure around an FSW.
Citation: Aerospace
PubDate: 2023-09-08
DOI: 10.3390/aerospace10090790
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 791: Recent Advances in Airfoil Self-Noise
Passive Reduction
Authors: Behzad Amirsalari, Joana Rocha
First page: 791
Abstract: Airflow-induced noise prediction and reduction is one of the priorities for both the energy and aviation industries. This review paper provides valuable insights into flow-induced noise computation, prediction, and optimization methods with state-of-the-art efforts in passive noise reduction on airfoils, blades, and wings. This review covers the combination of several approaches in this field, including analytical, numerical, empirical, semi-empirical, artificial intelligence, and optimization methods. Under passive noise reduction techniques, leading and trailing edge treatments, porous materials, controlled diffusion airfoils, morphing wings, surface treatments, and other unique geometries that researchers developed are among the design modification methods discussed here. This work highlights the benefits of incorporating multiple techniques to achieve the best results concerning the desired application and design. In addition, this work provides an overview of the advantages and disadvantages of each tool, with a particular emphasis on the possible challenges when implementing them. The methods and techniques discussed herein will help increase the acoustic efficiency of aerial structures, making them a beneficial resource for researchers, engineers, and other professionals working in aviation noise reduction.
Citation: Aerospace
PubDate: 2023-09-08
DOI: 10.3390/aerospace10090791
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 792: GPU Acceleration of CFD Simulations in
OpenFOAM
Authors: Federico Piscaglia, Federico Ghioldi
First page: 792
Abstract: We introduce algorithmic advancements designed to expedite simulations in OpenFOAM using GPUs. These developments include the following. (a) The amgx4Foam library, which connects the open-source AmgX library from NVIDIA to OpenFOAM. Matrix generation, involving tasks such numerical integration and assembly, is performed on CPUs. Subsequently, the assembled matrix is processed on the CPU. This approach accelerates the computationally intensive linear solver phase of simulations on GPUs. (b) Enhancements to code performance in reactive flow simulations, by relocating the solution of finite-rate chemistry to GPUs, which serve as co-processors. We present code verification and validation along with performance metrics targeting two distinct application sets, namely, aerodynamics calculations and supersonic combustion with finite-rate chemistry.
Citation: Aerospace
PubDate: 2023-09-08
DOI: 10.3390/aerospace10090792
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 793: Numerical Analysis of Bioinspired Tails in
a Fixed-Wing Micro Air Vehicle
Authors: Estela Barroso Barderas, Rafael Bardera Mora, Ángel Antonio Rodriguez-Sevillano, Juan Carlos Matías García
First page: 793
Abstract: Bird tails play a key role in aerodynamics and flight stability. They produce extra lift for takeoff and landing maneuvers, enhance wing functions and maintain stability during flight (keeping the bird from yawing, rolling and pitching, or otherwise losing control). This paper investigates the use of bioinspired horizontal stabilizers for Micro Air Vehicles (MAVs) involving a Zimmerman wing-body geometry. A selection of five tail shapes of the main types existing in nature is presented, and a parametric analysis is conducted looking into the influence of the most relevant tail geometric parameters to increase the longitudinal static stability of the vehicle. Based on the parametric study, a smaller subset of candidate tail designs are shortlisted to perform a detailed aerodynamic analysis. Then, steady RANS CFD simulations are conducted for a higher-fidelity study of these candidate tail designs to obtain an optimum of each tail type. The criterion for selection of the optimum tail configuration is the maximum aerodynamic efficiency, CLCD , as well as a high longitudinal static stability. The squared-fan tail provides the highest aerodynamic efficiency while maintaining a high longitudinal stability of the vehicle. In conclusion, this paper provides an innovative study of improving longitudinal stability and aerodynamics through the implementation of bioinspired horizontal stabilizers in vehicles with these characteristics.
Citation: Aerospace
PubDate: 2023-09-08
DOI: 10.3390/aerospace10090793
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 794: Stiffness Design of Active Capture
Claw-Type Docking Mechanism for Lunar Sample Return
Authors: Weijun Wang, Chongfeng Zhang, Chenkun Qi, Lijia Fu, Shigang Wang
First page: 794
Abstract: The docking mechanism is the key system for realizing the lunar-orbit docking mission of two spacecraft, which needs to have both capture correction and connection hold functions. The different stiffness requirements between the capture correction process, where low stiffness is desired, and the connection hold process, where high stiffness is desired, pose a significant challenge to the design of the docking mechanism. In this paper, an active capture claw docking mechanism is designed. Under the constraints of being lightweight and having an envelope size, three sets of independent claw mechanisms are designed using the modular design idea to achieve the performance optimization and function integration of the docking mechanisms. The theoretical model of the collision dynamics between the active and passive docking mechanisms is established; the stiffness value range of the docking mechanism is determined, and the typical docking conditions are simulated and verified. The results show that the stiffness design in this paper can satisfy the requirements of the two docking processes. The active capture claw docking mechanism developed was applied to the lunar surface sample return mission successfully and played an important role in the lunar-orbit docking mission.
Citation: Aerospace
PubDate: 2023-09-10
DOI: 10.3390/aerospace10090794
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 795: Predictor–Corrector Guidance for a
Hypersonic Morphing Vehicle
Authors: Dongdong Yao, Qunli Xia
First page: 795
Abstract: In an effort to address the problem of hypersonic morphing vehicles reaching the target while avoiding no-fly zones, an improved predictor–corrector guidance method is proposed. Firstly, the aircraft motion model and the constraint model are established. Then, the basic algorithm is given. The Q-learning method is used to design the attack angle and sweep angle scheme to ensure that the aircraft can fly over low-altitude zones. The B-spline curve is used to determine the locations of flight path points, and the bank angle scheme is designed using the predictor–corrector method, so that the aircraft can avoid high-altitude zones. Next, the Monte Carlo reinforcement learning (MCRL) method is used to improve the predictor–corrector method and a Deep Neural Network (DNN) is used to fit the reward function. The planning method in this paper realizes the use of a variable sweep angle, while the improved method further improves the performance of the trajectory, including the attainment of greater final speed and a smaller turning angle. The simulation results verify the effectiveness of the proposed algorithm.
Citation: Aerospace
PubDate: 2023-09-11
DOI: 10.3390/aerospace10090795
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 796: A New Flow Control and Efficiency
Enhancement Method for Horizontal Axis Wind Turbines Based on Segmented
Prepositive Elliptical Wings
Authors: Xuan Bai, Hao Zhan, Baigang Mi
First page: 796
Abstract: Flow separation occurs when wind turbines operate under large inflow conditions, which seriously affects the utilization of wind energy and reduces the output power of the blade. Therefore, a composite flow control configuration for horizontal axis wind turbines, founded on segmented prepositive elliptical wings, is proposed for efficiency enhancement. Taking a typical NREL Phase VI wind turbine as the prototype, its separation effect is evaluated by the CFD method. Then, starting from the improvement of the two-dimensional airfoil flow, the prepositive elliptic wing is designed according to the airfoil flow, and the optimal two-dimensional flow control configuration of the blade airfoil is obtained by simulation analysis. Finally, the two-dimensional configuration is extended to three-dimensional, and the aerodynamic characteristics of the blade before and after flow control are simulated and compared. The results show that, at wind speeds of 10~20 m/s, flow separation on the blade is effectively inhibited; meanwhile, the pressure difference between the pressure surface and the suction surface increases. These characteristics greatly improve the performance of wind turbine and increase its torque by more than 30%. Moreover, when the flow control effect cannot be reached, the blade torque is only reduced by approximately 2%.
Citation: Aerospace
PubDate: 2023-09-12
DOI: 10.3390/aerospace10090796
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 797: Adjoint and Direct Characteristic Equations
for Two-Dimensional Compressible Euler Flows
Authors: Kevin Ancourt, Jacques Peter, Olivier Atinault
First page: 797
Abstract: The method of characteristics is a classical method for gaining understanding in the solution of a partial differential equation. It has recently been applied to the adjoint equations of the 2D steady-state Euler equations and the first goal of this paper is to present a linear algebra analysis that greatly simplifies the discussion of the number of independent characteristic equations satisfied along a family of characteristic curves. This method may be applied for both the direct and the adjoint problem. Our second goal is to directly derive in conservative variables the characteristic equations of 2D compressible inviscid flows. Finally, the theoretical results are assessed for a nozzle flow with a classical scheme and its dual consistent discrete adjoint.
Citation: Aerospace
PubDate: 2023-09-12
DOI: 10.3390/aerospace10090797
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 798: Response of the Shock Wave/Boundary Layer
Interaction to Disturbances Induced by the Plasma Discharge
Authors: Oleg Vishnyakov, Pavel Polivanov, Andrey Sidorenko
First page: 798
Abstract: The paper focuses on the investigation of unsteady effects in shock wave/boundary layer interaction. The study was carried out using a flat plate model subjected to a free stream Mach number of 1.43 and a unit Reynolds number (Re1) of 11.5 × 106 1/m. To generate two-dimensional disturbances in the laminar boundary layer upstream of the separation region, a dielectric barrier discharge was employed. The disturbances were generated within the frequency range of 500 to 1700 Hz. The Strouhal numbers based on the length of the separation bubble ranged from 0.04 to 0.13. The measurements were carried out using a hot-wire anemometer. Analysis of the data shows that disturbances in this frequency range mostly decay. The maximum amplitudes of perturbations were observed at frequencies of 1250 Hz and 1700 Hz.
Citation: Aerospace
PubDate: 2023-09-13
DOI: 10.3390/aerospace10090798
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 799: Suggestions for Criteria to Evaluate
Lateral-Directional Nonlinear Pilot-Induced Oscillations Due to
Fly-by-Wire Civil Aircraft Landing Configuration Switch
Authors: Lixin Wang, Chang Lu, Tao Jin, Hailiang Liu, Ting Yue
First page: 799
Abstract: Using a nonlinear pilot-induced oscillation prediction method based on digital virtual flight simulation calculations, digital experiments on predicting lateral-directional nonlinear pilot-induced oscillations due to landing configuration switching of fly-by-wire civil aircraft with different closed-loop dynamic characteristics are carried out. It is proposed that the lateral-directional pilot-induced oscillations due to the landing configuration switch can be evaluated using the changes in dynamic characteristic parameters before and after the configuration switch. The quantitative boundaries of the dynamic characteristic parameters of an example aircraft are determined, and a criterion suggestion is formed to predict the lateral-directional nonlinear pilot-induced oscillations due to landing configuration switching. This study provides a reference for the optimal design of the lateral-directional flight control law of fly-by-wire aircraft during the approach stage and provides suggestions for the formulation of evaluation criteria for other nonlinear pilot-induced oscillation phenomena.
Citation: Aerospace
PubDate: 2023-09-13
DOI: 10.3390/aerospace10090799
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 800: Combustion Characteristics of HTPB-Based
Hybrid Rocket Fuels: Using Nickel Oxide as the Polymer Matrix Pyrolysis
Catalyst
Authors: Hongsheng Yu, Xiaodong Yu, Hongwei Gao, Luigi T. DeLuca, Wei Zhang, Ruiqi Shen
First page: 800
Abstract: The slow regression rate induced by the high pyrolysis difficulty has limited the application and development of hydroxyl-terminated polybutadiene (HTPB)-based fuels in hybrid rocket propulsion. Nickel oxide (NiO) shows the possibility of increasing the regression rate of HTPB-based fuels by catalyzing the pyrolysis process of the polymer matrix in our previous investigation; hence, this paper studies the NiO particles in the thermal decomposition and combustion of HTPB fuel grains. The DSC/TG test shows that NiO can intensely decrease the thermal stability of HTPB, and the catalytic effect of NiO is mainly reflected in the final decomposition stages of polybutadiene components. 5 wt% NiO enhances the regression rate by 19.4% and 13.7% under an oxygen mass flux of 50 kg/m2s and 150 kg/m2s, respectively. Further investigation shows that NiO particles will also cause the reduction of combustion heat and the agglomeration at the regressing surface while catalyzing the pyrolysis process, improving the thermal conductivity, and promoting the radiative heat transfer of the HTPB-based fuels; thus, more NiO additive (5 wt% < [NiO] ≤ 10 wt%) does not lead to a faster regression rate in HTPB-based fuels. This study demonstrates the catalytic effect of NiO on the polymer matrix for HTPB-based fuels, showing the attractive application prospects of this additive in HTPB-containing fuel grains.
Citation: Aerospace
PubDate: 2023-09-13
DOI: 10.3390/aerospace10090800
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 801: Aeroelasticity Model for Highly Flexible
Aircraft Based on the Vortex Lattice Method
Authors: Mindaugas Dagilis, Sigitas Kilikevičius
First page: 801
Abstract: With the increasing use of composite materials in aviation, structural aircraft design often becomes limited by stiffness, rather than strength. As a consequence, aeroelastic analysis becomes more important to optimize both aircraft structures and control algorithms. A low computational cost aeroelasticity model based on VLM and rigid-body dynamics is proposed in this work. UAV flight testing is performed to evaluate the accuracy of the proposed model. Two flight sections are chosen to be modeled based on recorded aerodynamic surface control data. The calculated accelerations are compared with recorded flight data. It is found that the proposed model adequately captures the general flight profile, with acceleration peak errors between −6.2% and +8.4%. The average relative error during the entire flight section is 39% to 44%, mainly caused by rebounds during the beginning and end of pull-up maneuvers. The model could provide useful results for the initial phases of aircraft control law design when comparing different control algorithms.
Citation: Aerospace
PubDate: 2023-09-14
DOI: 10.3390/aerospace10090801
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 802: Neck Structure Optimal Design of the
Turbine Wheel for Containment Design of the Air Turbine Starter
Authors: Liqiang Chen, Haijun Xuan, Wenbin Jia, Jianxin Liu, Zehui Fang, Yao Zheng
First page: 802
Abstract: The airworthiness standards of the transport category airplanes stipulate that the high energy rotor equipment must be of the sufficient containment capacity. It is of great importance to study the containment and weight reduction for the air turbine starter. In this paper, based on an OSF design, Kriging response surface model and MOGA algorithm, a neck structure optimal design method was proposed for the air turbine wheel. Using the optimal design method, the optimal structural parameters were suggested as the design parameters, and verified by the over-speed burst test. The maximum errors of the burst speeds between the experimental and design values are less than 2%, and the neck structure turbine wheel breaks in the neck as expected, validating the accuracy of the optimal design method. Then, the effects of turbine wheel burst modes on the containment were investigated quantitatively, and verified by the containment tests. Based on the experimental and simulation results, the containment design method was proposed for the neck structure turbine wheel. The results show that compared with the trisection wheel burst, the rim burst dramatically decrease the mass and initial kinetic energy of burst released fragments by 63.3% and 24.8%, thereby greatly reducing the thickness and the mass of the containment ring by 29.5% and 29.1%.
Citation: Aerospace
PubDate: 2023-09-14
DOI: 10.3390/aerospace10090802
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 803: Preliminary Analysis of the Performance of
an Electric Supersonic Propeller
Authors: Jens Kunze, Allan Paull
First page: 803
Abstract: A preliminary aerodynamic and thermodynamic analysis of a supersonic propeller driven by an electric motor is performed. The analysis is aimed at determining whether such a system is feasible and further and more detailed investigation is warranted. Recent progress in electric energy storage and motors, as well as high temperature and lightweight materials, has opened up the design space for a large number of applications. Electrically powered flight and propellers are among these applications. This study shows that very good aerodynamic and propulsive efficiencies can be achieved with this combination. In this paper, the design space of supersonic propeller blades is explored and the effect of a number of design parameters on the blade efficiency is shown. Further analysis is performed to demonstrate that reasonable efficiency can be achieved at flight Mach numbers from two to six between 15 and 35 km altitude. Finally, a mission-based propeller design study is performed to demonstrate practical system performance and show trade-offs between different parameters.
Citation: Aerospace
PubDate: 2023-09-14
DOI: 10.3390/aerospace10090803
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 804: Task Offloading with Data-Dependent
Constraints in Satellite Edge Computing Networks: A Multi-Objective
Approach
Authors: Ruipeng Zhang, Yanxiang Feng, Yikang Yang, Xiaoling Li
First page: 804
Abstract: Senabling a satellite network with edge computing capabilities, SEC provides users with a full range of computing service. In this paper, we construct a multi-objective optimization model for task offloading with data-dependent constraints in an SEC network and aim to achieve optimal tradeoffs among energy consumption, cost, and makespan. However, dependency constraints between tasks may lead to unexpected computational delays and even task failures in an SEC network. To solve this, we proposed a Petri-net-based constraint amending method with polynomial complexity and generated offloading results satisfying our constraints. For the multiple optimization objectives, a strengthened dominance relation sort was established to balance the convergence and diversity of nondominated solutions. Based on these, we designed a multi-objective wolf pack search (MOWPS) algorithm. A series of adaptive mechanisms was employed for avoiding additional computational overhead, and a Lamarckian-learning-based multi-neighborhood search prevents MOWPS from becoming trapped in the local optimum. Extensive computational experiments demonstrate the outperformance of MOWPS for solving task offloading with data-dependent constraints in an SEC network.
Citation: Aerospace
PubDate: 2023-09-14
DOI: 10.3390/aerospace10090804
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 805: The Development and Application of
Two-Color Pressure-Sensitive Paint in Jet Impingement Experiments
Authors: Wei-Chieh Chen, Chih-Yung Huang, Kui-Thong Tan, Hirotaka Sakaue
First page: 805
Abstract: This study aimed to develop a two-color pressure-sensitive paint (PSP) that has both high pressure sensitivity and high temperature sensitivity. Different nitrobenzoxadiazole (NBD) derivatives were used as the temperature probe. Among them, NBD-ZY37 demonstrated favorable stability against photodegradation, and its temperature sensitivity in an RTV118-based two-color PSP was −1.4%/°C. Moreover, temperature sensitivity was independent of pressure in the tested temperature range. PtTFPP was used, and its pressure sensitivity was measured to be 0.5% per kPa. The two-color PSP paint underwent further examination in jet impingement experiments. The experimental results indicated that the pressure fluctuation introduced by the shock waves occurred earlier at higher impingement angles. Specifically, when the pressure ratio was 2.38, increasing the impinging angle from 15° to 30° caused the location of the pressure wave to move from s/D at 0.8 to the exit of the nozzle. Simultaneously, the shape of the maximum pressure zone changed from a fan shape to a round shape. Additionally, the jet region expanded when the pressure ratio was increased.
Citation: Aerospace
PubDate: 2023-09-15
DOI: 10.3390/aerospace10090805
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 806: Parameter Identification of Pilot Model and
Stability Analysis of Human-in-Loop Image Seeker
Authors: Yi Zhang, Tao Li, Yanning Li, Gen Wang
First page: 806
Abstract: In the human-in-loop (HIL) guidance mode, a pilot quickly identifies and flexibly locks on to a target through a real-time image signal transmitted by the aircraft. Then, the line-of-sight (LOS) angle error in the viewing field is tracked and compensated for in order to improve the guidance and control performance of the image-guided aircraft. Based on the physical structure and device parameters of the image seeker, an appropriate correction network is designed to improve the performance of the seeker stability loop. Aiming at a precise-extended crossover (PEC) pilot model, the structure of the dynamic model is optimized, and the maximum likelihood estimation (MLE) method of the output error structure is used to identify the dynamic parameters. This makes up for the deficiency of the existing modeling. In order to solve the nonlinear optimization problems encountered in the identification process, a hybrid strategy of a genetic algorithm (GA) and Gauss–Newton optimization algorithm is used to improve the probability of finding the global optimal solution. The simplex method is also used to improve the robustness of the algorithm. In addition, a hardware-in-the-loop simulation is designed and multi-round HIL experiment flow is performed. Moreover, based on the adaptability of the pilot to different image signal delays, the effects of different image signal delays on the stability and disturbance rejection rate (DRR) of the seeker control system are studied. The results demonstrate that the hybrid gradient optimization algorithm (HGOA) can find the global optimal value, and the identification model can accurately reflect the dynamic characteristics of the pilot. In the HIL guidance mode, the tracking compensation behavior of the pilot can reduce the influence of image signal delay on the disturbance of the aircraft body isolated by the seeker. The optimized PEC model and the identified dynamic parameters improve the efficiency of pilot training and screening.
Citation: Aerospace
PubDate: 2023-09-15
DOI: 10.3390/aerospace10090806
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 807: A Study on the Derivation of Atmospheric
Water Vapor Based on Dual Frequency Radio Signals and Intersatellite
Communication Networks
Authors: Ramson Munyaradzi Nyamukondiwa, Necmi Cihan Orger, Daisuke Nakayama, Mengu Cho
First page: 807
Abstract: The atmospheric total water vapor content (TWVC) affects climate change, weather patterns, and radio signal propagation. Recent techniques such as global navigation satellite systems (GNSS) are used to measure TWVC but with either compromised accuracy, temporal resolution, or spatial coverage. This study demonstrates the feasibility of predicting, mapping, and measuring TWVC using spread spectrum (SS) radio signals and software-defined radio (SDR) technology on low Earth-orbiting (LEO) satellites. An intersatellite link (ISL) communication network from a constellation of small satellites is proposed to achieve three-dimensional (3D) mapping of TWVC. However, the calculation of TWVC from satellites in LEO contains contribution from the ionospheric total electron content (TEC). The TWVC and TEC contribution are determined based on the signal propagation time delay and the satellites’ positions in orbit. Since TEC is frequency dependent unlike TWVC, frequency reconfiguration algorithms have been implemented to distinguish TWVC. The novel aspects of this research are the implementation of time stamps to deduce time delay, the unique derivation of TWVC from a constellation setup, the use of algorithms to remotely tune frequencies in real time, and ISL demonstration using SDRs. This mission could contribute to atmospheric science, and the measurements could be incorporated into the global atmospheric databases for climate and weather prediction models.
Citation: Aerospace
PubDate: 2023-09-15
DOI: 10.3390/aerospace10090807
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 808: A Turbulent Inflow Generation Method for
the LES of High Re Flow by Scaling Low Re Flow Data
Authors: Lei Luo, Honghu Ji
First page: 808
Abstract: The rescaling–recycling method (RRM) is usually used to generate turbulent inflow for the LES of compressible wall-bounded flows, which can lead to relatively high computational cost for high Re flows since the mesh resolution increases exponentially with Re number. A turbulent inflow generation method based on the scaling of low Re flow, referred as TIG-LowRe, is proposed, aiming at reducing the computational cost when applying the RRM. To validate the proposed method, the TIG-LowRe method was applied to generate turbulent inflow for the LES of a non-isothermal round jet flow at Re = 86,000. Two cases were carried out with the inflow generated based on two round pipe flows at Re = 10,000 and 24,000. The results show that the mean and fluctuating temperatures of the two cases agree well with the experimental data. In the case of low Re flow at Re = 10,000, the jet flow decays too fast along the axial direction, the mean and fluctuating axial velocities are over-predicted and the radial fluctuating velocity is under-predicted. By increasing the Re of the low Re flow to 24,000, the decay rate of the jet flow decreases and the accuracies of the mean and fluctuating axial velocities are obviously improved, while the radial fluctuating velocity shifts further away from the experimental data. The main reason for the difference between the two cases is that more fine turbulent structure of the inflow in case-Re10000 is lost than in case-Re24000 during the turbulence generation process.
Citation: Aerospace
PubDate: 2023-09-15
DOI: 10.3390/aerospace10090808
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 809: On the Aeroelasticity of a Cantilever Wing
Equipped with the Spanwise Morphing Trailing Edge Concept
Authors: Jafar S. Pilakkadan, Rafic M. Ajaj, Zawar Haider, Mohammadreza Amoozgar
First page: 809
Abstract: This paper studies the aeroelastic behavior of a rectangular, cantilever wing equipped with the spanwise morphing trailing edge (SMTE) concept. The SMTE consists of multiple trailing edge flaps that allow controlling the spanwise camber distribution of a wing. The flaps are attached at the wing’s trailing edge using torsional springs. The Rayleigh–Ritz method is used to develop the equations of motion of the wing-flap system. The use of shape functions allows for representing the wing as an equivalent 2D airfoil with generalized coordinates that are defined at the wingtip. Strip theory, based on Theodorsen’s unsteady aerodynamic model, is used to compute the aerodynamic loads acting on the wing. A representative Padé approximation for Theodorsen’s function is utilized to model the aerodynamic behaviors in a state-space form allowing time-domain simulation and analysis. The model is validated using a rectangular cantilever wing and the data are available in the literature. A comprehensive parametric comparison study is conducted to assess the impact of flap stiffness on the aeroelastic boundary. In addition, the potential of the SMTE to provide load alleviation and flutter suppression is assessed for a wide range of flight conditions, using a discrete (1-cosine) gust. Finally, the implementation and validation of a controller for a wing with SMTE for gust load alleviation are studied and controller parameters are tuned for a specific gust model.
Citation: Aerospace
PubDate: 2023-09-15
DOI: 10.3390/aerospace10090809
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 810: Effect of Bending Deformation on the
Lateral Force of Spinning Projectiles with Large Aspect Ratio
Authors: Qi Liu, Juanmian Lei, Yong Yu, Jintao Yin
First page: 810
Abstract: The bending deformation can affect the lateral force of spinning projectiles with large aspect ratios, thus interfering with their flight stability. Based on the established spin–deformation coupling motion model, the unsteady Reynolds averaged Navier–Stokes (URANS) equations are solved to simulate the flow over a large−aspect−ratio projectile undergoing spin and spin−deformation coupling motion by using the dual−time stepping method and dynamic mesh technique, obtaining the lateral force. Furtherly, the flow mechanism is analyzed for the changed lateral force induced by the bending deformation. The results indicate that the variation of transient lateral force for the head of a projectile is consistent with that of the deformation−induced additional sideslip angle; affected by the deformation−induced compression wave and expansion wave, the time−averaged lateral force for the middle of a projectile will be increased at small angles of attack, but changed little at large angles of attack; at small angles of attack, the change trend of transient lateral force for the tail of a projectile is similar to that of additional angle of attack caused by the deformation; at large angles of attack, the characteristic of phase lag is presented between the transient lateral force for the tail of a projectile and the additional sideslip angle.
Citation: Aerospace
PubDate: 2023-09-15
DOI: 10.3390/aerospace10090810
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 811: 3D Soft-Landing Dynamic Theoretical Model
of Legged Lander: Modeling and Analysis
Authors: Zhiyi Wang, Chuanzhi Chen, Jinbao Chen, Guang Zheng
First page: 811
Abstract: In this paper, a novel 3D (three-dimensional) soft-landing dynamic theoretical model of a legged lander is developed in detail as well as its numerical solution process. The six degrees of freedom motion (6-DOF) of the base model of the lander with mass center offset setting is considered in the model as well as the spatial motion (3-DOF) of each landing gear. The characteristics of the buffering force, the footpad–ground contact, and the inter-structure friction are also taken into account during the motion of each landing gear. The direct constraint violation correction is used to control the constraint stabilization of the nonlinear dynamic equation. Comparative studies between the results from the proposed model and the simulated model (built in MSC Adams) under four classical load cases show the validity of the model. Additionally, the influences of different types of contact force models, friction force models, and a friction correction model used in the soft-landing dynamic model are further investigated as a step toward understanding the soft-landing dynamic performance and the feasibility of the dynamic model method of a legged lander. The results indicate that a precise lateral force model of the footpad–ground contact is necessary to obtain the soft-landing performance of one lander during soft landing.
Citation: Aerospace
PubDate: 2023-09-15
DOI: 10.3390/aerospace10090811
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 812: Investigation of Harmonic Response in
Non-Premixed Swirling Combustion to Low-Frequency Acoustic Excitations
Authors: Jinrong Bao, Chenzhen Ji, Deng Pan, Chao Zong, Ziyang Zhang, Tong Zhu
First page: 812
Abstract: The propagation mechanism of flow disturbance under acoustic excitations plays a crucial role in thermoacoustic instability, especially when considering the effect of non-premixed combustion on heat release due to reactant mixing and diffusion. This relationship leads to a complex coupling between the spatial distribution of the equivalence ratio and the propagation mechanism of flow disturbance. In the present study, the response of a methane-air non-premixed swirling flame to low-frequency acoustic excitations was investigated experimentally. By applying Proper Orthogonal Decomposition (POD) analysis to CH* chemiluminescence images, the harmonic flame response was revealed. Large Eddy Simulation (LES) was utilized to analyze the correlation between the vortex motion within the shear layers and the harmonic response under non-reacting conditions at excitation frequencies of 20 Hz, 50 Hz, and 150 Hz. The results showed that the harmonic flame response was mainly due to the harmonic velocity pulsations within the shear layers. The acoustically induced vortices within the shear layer exhibited motion patterns susceptible to harmonic interference, with spatial distribution characteristics closely related to the oscillation modes of the non-premixed combustion.
Citation: Aerospace
PubDate: 2023-09-15
DOI: 10.3390/aerospace10090812
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 813: Electric Aerospace Actuator Manufactured by
Laser Powder Bed Fusion
Authors: Borja Lizarribar, Borja Prieto, Miren Aristizabal, Jose Manuel Martín, Miguel Martínez-Iturralde, Ekain San José, Ione Golvano, Sergio Montes
First page: 813
Abstract: Recent advances in manufacturing methods have accelerated the exploration of new materials and advantageous shapes that could not be produced by traditional methods. In this context, additive manufacturing is gaining strength among manufacturing methods for its versatility and freedom in the geometries that can be produced. Taking advantage of these possibilities, this research presents a case study involving an electric aerospace actuator manufactured using additive manufacturing. The main objectives of this research work are to assess the feasibility of additively manufacturing electric actuators and to evaluate potential gains in terms of weight, volume, power consumption and cost over conventional manufacturing technologies. To do so and in order to optimise the actuator design, a thorough material study is conducted in which three different magnetic materials are gas-atomised (silicon iron, permendur and supermalloy) and test samples of the most promising materials (silicon iron and permendur) are processed by laser powder bed fusion. The final actuator design is additively manufactured in permendur for the stator and rotor iron parts and in 316L stainless steel for the housing. The electric actuator prototype is tested, showing compliance with design requirements in terms of torque production, power consumption and heating. Finally, a design intended to be manufactured via traditional methods (i.e., punching and stacking for the stator laminations and machining for the housing) is presented and compared to the additively manufactured design. The comparison shows that additive manufacturing is a viable alternative to traditional manufacturing for the application presented, as it highly reduces the weight of the actuator and facilitates the assembly, while the cost difference between the two designs is minimal.
Citation: Aerospace
PubDate: 2023-09-17
DOI: 10.3390/aerospace10090813
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 814: Bridging the Gap between Simulation and
Real Autonomous UAV Flights in Industrial Applications
Authors: Rafael Perez-Segui, Pedro Arias-Perez, Javier Melero-Deza, Miguel Fernandez-Cortizas, David Perez-Saura, Pascual Campoy
First page: 814
Abstract: The utilization of autonomous unmanned aerial vehicles (UAVs) has increased rapidly due to their ability to perform a variety of tasks, including industrial inspection. Conducting testing with actual flights within industrial facilities proves to be both expensive and hazardous, posing risks to the system, the facilities, and their personnel. This paper presents an innovative and reliable methodology for developing such applications, ensuring safety and efficiency throughout the process. It involves a staged transition from simulation to reality, wherein various components are validated at each stage. This iterative approach facilitates error identification and resolution, enabling subsequent real flights to be conducted with enhanced safety after validating the remainder of the system. Furthermore, this article showcases two use cases: wind turbine inspection and photovoltaic plant inspection. By implementing the suggested methodology, these applications were successfully developed in an efficient and secure manner.
Citation: Aerospace
PubDate: 2023-09-17
DOI: 10.3390/aerospace10090814
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 815: A 6U CubeSat Platform for Low Earth Remote
Sensing: DEWASAT-2 Mission Concept and Analysis
Authors: Ann Mary Eapen, Sidi Ahmed Bendoukha, Reem Al-Ali, Abdulrahman Sulaiman
First page: 815
Abstract: This paper presents an in-depth analysis of DEWASAT-2, a 6U CubeSat designed for low Earth remote sensing applications. DEWASAT-2 is equipped with two payloads: a high-resolution camera for Earth observation and a spectrometer for detecting greenhouse gases. This paper describes the mission analysis and design of DEWASAT-2 as well as the link budget, power budget, and data budget. Additionally, the paper includes simulations and plots that illustrate the access times, lifetime, and other important parameters of the CubeSat. The outcomes presented in this article emphasise that DEWASAT-2 will contribute to fulfilling and enhancing various use cases of the Dubai Electricity and Water Authority (DEWA) network such as weather monitoring and forecasting and the detection of seawater salinity.
Citation: Aerospace
PubDate: 2023-09-18
DOI: 10.3390/aerospace10090815
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 816: A Research on Rotor/Ship Wake
Characteristics under Atmospheric Boundary Layer Conditions
Authors: Guoqiang Li, Qing Wang, Qijun Zhao, Guoqing Zhao, Fei Feng, Linxin Wu
First page: 816
Abstract: The environment for the shipboard landing and takeoff of helicopters is extremely complex and significantly affects their safe flight. To address the intricate characteristics of the flow field during these operations, a simulation method suitable for rotor/ship wake vortex interaction is developed. This method couples the Delayed Detached Eddy Simulation (DDES) method and the momentum source method. The simulation of flow field characteristics of the SFS2 ship model under different conditions reveals that, in a rotor/ship coupling scenario, the inflow velocity in the wake zone of the flight deck is distributed in a “W” shape due to the influence of the rotor blade tip vortex. Under wind shear conditions, the rotor’s influence on the wake is reduced, resulting in smaller velocity fluctuations compared to uniform inflow conditions. Moreover, the detached eddy is suppressed to some extent. It can be concluded that shear flow mitigates the unsteady characteristics of the ship’s wake zone to some extent, which is beneficial to helicopter operations during takeoff and landing.
Citation: Aerospace
PubDate: 2023-09-18
DOI: 10.3390/aerospace10090816
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 817: Numerical Investigation of Stall
Characteristics of Common Research Model Configuration Based on Zonal
Detached Eddy Simulation Method
Authors: Xin Zhang, Heng Zhang, Jie Li
First page: 817
Abstract: A zonal detached eddy simulation (ZDES) method, based on the two-equation k-ω SST turbulence model, was employed to predict stall characteristics and capture small-scale vortex structures in the wake region of the main wing under the post-stall condition of the Common Research Model (CRM) configuration. Additionally, the unsteady Reynolds-averaged Navier–Stokes (URANS) method was utilized for performance comparison in resolving small-scale vortices with ZDES. The results revealed a pronounced lateral flow on the wing, induced by the low-pressure region of the inner wing at post-stall angles of attack. Due to the downwash effect, the horizontal tail was influenced by the vortices in the wake region of the main wing, which the URANS method did not capture adequately. As the angle of attack increased, the separation area on the main wing expanded from the middle of the wing towards the inner wing. Consequently, the vortex structures in the wake region of the main wing became more intricate, and the primary peak of the lift coefficient spectrum shifted to the low-frequency region.
Citation: Aerospace
PubDate: 2023-09-18
DOI: 10.3390/aerospace10090817
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 818: Using the Impulse Method to Determine
High-Pressure Dynamic Burning Rate of Solid Propellants
Authors: Jiahao Liu, Yinghong Wang, Xinyang Li, Junhao Cong
First page: 818
Abstract: A new method for determining the burning rate of a solid propellant, called the Impulse Method, is proposed in this paper. It is based on the proportional relationship between the impulse generated and the mass of the burned propellant. The pressure–time and thrust–time curves are obtained from a tubular propellant grain burning in the chamber, whose inner surface serves as the initial burning surface. Consequently, the mass of the propellant that was burned off at different pressures can be determined, and the burning rates at different pressures are derived according to the geometric parameters of the propellant grain. The Impulse Method was applied to test the burning rate of two types of propellants twice. The results show that the burning rates were consistent for the same propellant at corresponding pressures, demonstrating the feasibility and reliability of the Impulse Method. The burning rate of a GAP-based composite propellant at 20 MPa measured using the Standard Motor Method was 22.6 mm/s, and that measured using the Impulse Method was 22.2 mm/s and 22.7 mm/s, respectively. These findings indicate that the two methods have comparable accuracy. However, the Impulse Method has the advantage of obtaining the burning rate of the solid propellant at any pressure through a single test. In addition, the nozzle erosion only affected the pressure and not the burning rate. Finally, the rationality of the approach for determining the actual specific impulse was proven by comparing the results with those from another testing method.
Citation: Aerospace
PubDate: 2023-09-18
DOI: 10.3390/aerospace10090818
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 819: Bibliometric Analysis of Engine Vibration
Detection
Authors: Mai Xin, Zhifeng Ye, Tong Zhang, Xiong Pan
First page: 819
Abstract: After many years of development, the technology of analyzing the working condition of power units based on vibration signals has received relatively stable applications, but the accuracy and the degree of automation and intelligence for fault diagnosis are still inadequate due to the limitations in the ongoing development of key technologies. With the development of big data and artificial intelligence technology, the involvement of new technologies will be an important boost to the development of this field. In this study, in order to support subsequent research, bibliometrics is used as a tool to sort the development of the technology in this field at the macro level. At the micro level, key publications in the literature are studied to better understand the development status at the technical level and prepare for the selection of entry points to facilitate in-depth innovation in the future.
Citation: Aerospace
PubDate: 2023-09-20
DOI: 10.3390/aerospace10090819
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 820: An Improved Multi-Objective Particle Swarm
Optimization Method for Rotor Airfoil Design
Authors: Yongchuan Wu, Gang Sun, Jun Tao
First page: 820
Abstract: In this study, a multi-objective aerodynamic optimization is performed on the rotor airfoil via an improved MOPSO (multi-objective particle swarm optimization) method. A database of rotor airfoils containing both geometric and aerodynamic parameters is established, where the geometric parameters are obtained via the CST (class shape transformation) method and the aerodynamic parameters are obtained via CFD (computational fluid dynamics) simulations. On the basis of the database, a DBN (deep belief network) surrogate model is proposed and trained to accurately predict the aerodynamic parameters of the rotor airfoils. In order to improve the convergence rate and global searching ability of the standard MOPSO algorithm, an improved MOPSO framework is established. By embedding the DBN surrogate model into the improved MOPSO framework, multi-objective and multi-constraint aerodynamic optimization for the rotor airfoil is performed. Finally, the aerodynamic performance of the optimized rotor airfoil is validated through CFD simulations. The results indicate that the aerodynamic performance of the optimized rotor airfoil is improved dramatically compared with the baseline rotor airfoil.
Citation: Aerospace
PubDate: 2023-09-20
DOI: 10.3390/aerospace10090820
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 821: Dynamic Analysis of a Large Deployable
Space Truss Structure Considering Semi-Rigid Joints
Authors: Huaibo Yao, Yixin Huang, Wenlai Ma, Lei Liang, Yang Zhao
First page: 821
Abstract: Joints are widely used in large deployable structures but show semi-rigidity due to performance degradation and some nonlinear factors affecting the structure’s dynamic characteristics. This paper investigates the influence of semi-rigid joints on the characteristics of deployable structures in orbit. A virtual connection element of three DOFs is proposed to model the semi-rigid joints. The governing equations of semi-rigid joints are established and integrated into the dynamic equation of the structures. A series of numerical experiments are carried out to validate the proposed model’s accuracy and efficiency, and the deployable truss structures’ static and dynamic responses are analyzed. The results show that semi-rigid joints exacerbate the effects of an in-orbit microvibration on the stability of deployable truss structures. Semi-rigid joints lower the dominant frequencies of structures, leading to a ‘closely-spaced-frequencies’ phenomenon and altering the dynamic responses significantly. The effects of semi-rigid joints on deployable truss structures are long-term and can be used to establish a relationship model between structural performance and service life. Nonlinear effects vary with the external load and depend on the structures’ instantaneous status. These results indicate that semi-rigid joints significantly influence the characteristics of deployable structures, which must be considered in the design and analysis of high-precision in-orbit deployable structures.
Citation: Aerospace
PubDate: 2023-09-21
DOI: 10.3390/aerospace10090821
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 822: Trend Analysis of Civil Aviation Incidents
Based on Causal Inference and Statistical Inference
Authors: Peng He, Ruishan Sun
First page: 822
Abstract: The efficient management of aviation safety requires the precise analysis of trends in incidents. While classical statistical models often rely on the autocorrelation of indicator sequences for trend fitting, significant room remains for performance improvement. To enhance the accuracy and interpretability of trend analyses for aviation incidents, we propose the Causal-ARIMA model, which is grounded in causal inference theory, and we employ four distinct modeling strategies to fit the trend of incidents in China’s civil aviation sector between 1994 and 2020. The objective is to validate the performance of the Causal-ARIMA model and identify optimal trend analysis strategies. The four modeling strategies account for causation factors, stationarity, and causality with operational volume, incorporating models like AR, ARMA, ARIMA, and Causal-ARIMA. Our findings reveal that ensemble techniques incorporating the Causal-ARIMA model (Strategy 2 and 3) outperform classical trend analysis methods (Strategy 1) in terms of model fit. Specifically, the causality-based binary fitting technique (Strategy 3) achieves the most uniformly dispersed fitting performance. When the premises for using the Causal-ARIMA model are relaxed, applying it to variables without Granger causal relationships results in uneven model performance (Strategy 4). According to our study, the Causal-ARIMA model can serve as a potent tool for the analysis of trends in the domain of aviation safety. Modeling strategies based on the Causal-ARIMA model provide valuable insights for aviation safety management.
Citation: Aerospace
PubDate: 2023-09-21
DOI: 10.3390/aerospace10090822
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 823: Very High Cycle Fatigue Life Prediction of
SLM AlSi10Mg Based on CDM and SVR Models
Authors: Yibing Yu, Linlin Sun, Zhi Bian, Xiaojia Wang, Zhe Zhang, Chao Song, Weiping Hu, Xiao Chen
First page: 823
Abstract: A novel fatigue evolution model considering the effect of defect size and additive manufacturing building direction based on the theories of continuum damage mechanics and its numerical implementation in ABAQUS is proposed in this paper. First, the constitutive model, fatigue damage evolution model and their parameter calibration methods are presented. Second, using the ABAQUS platform, the proposed model is implemented with user-defined subroutines. After that, based on the proposed model and its numerical implementation, the fatigue life of additively manufactured AlSi10Mg is predicted and its applicability is verified through experimental results. Finally, a support vector regression model is established to predict the fatigue life, and its results are compared to those of the numerical finite element method. The results show that the support vector regression model makes better predictions than the finite element method.
Citation: Aerospace
PubDate: 2023-09-21
DOI: 10.3390/aerospace10090823
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 824: Investigation of the Influence of Wake
Field Characteristic Structures on Downstream Targets Using the POD Method
Authors: Jiawei Fu, Junhui Wang, Jifei Wu, Ke Xu, Shuling Tian
First page: 824
Abstract: This research investigated the impact of complex low-speed wake flow structures on the aerodynamic characteristics of objects downstream. It employed the proper orthogonal decomposition (POD) method and the domain precursor simulation method to compare traditional methods and validate this approach. The study generated several flow structures of parallel dual-cylinder wakes with different scales and spacing. The variations in the aerodynamic coefficient of three downstream objects at various times passing through wakes of varying scales were appropriately compared and analyzed. The study established that the wake with a cylinder spacing of G = 1.5 has a more compact and concentrated modal structure than that with a cylinder spacing of G = 0.35. Smaller objects were more responsive to the wake flow structure with a spacing of G = 1.5, whereas larger objects responded more to the flow structure with a spacing of G = 0.35. The achieved results also revealed that the aerodynamic force coefficients of objects passing through the wakefield at different times were closely related to the temporal characteristics of the wake flow structure with different scales.
Citation: Aerospace
PubDate: 2023-09-21
DOI: 10.3390/aerospace10090824
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 825: Flow Field Reconstruction of 2D Hypersonic
Inlets Based on a Variational Autoencoder
Authors: Zuwei Tan, Runze Li, Yufei Zhang
First page: 825
Abstract: The inlet is one of the most important components of a hypersonic vehicle. The design and optimization of the hypersonic inlet is of great significance to the research and development of hypersonic vehicles. In recent years, artificial intelligence techniques have been used to improve the efficiency of aerodynamic optimization. Deep generative models, such as variational autoencoder (VAE) and generative adversarial network (GAN), have been used in a variety of flow problems in the last two years, making fast reconstruction and prediction of the full flow field possible. In this study, a hybrid multilayer perceptron (MLP) combined with a VAE network is used to reconstruct and predict the flow field of a two-dimensional multiwedge hypersonic inlet. The obtained results show that the VAE network can reconstruct the overall flow structure of the hypersonic flow field with high accuracy. The reconstruction accuracy of complex flow structures, such as shockwaves, boundary layers, and separation bubbles, is satisfactory. The flow field prediction model based on the MLP-VAE hybrid model has a strong generalization and generation ability, achieving relatively accurate flow field prediction for inlets with geometric configurations outside the training set.
Citation: Aerospace
PubDate: 2023-09-21
DOI: 10.3390/aerospace10090825
Issue No: Vol. 10, No. 9 (2023)
- Aerospace, Vol. 10, Pages 826: A High-Confidence Intelligent Measurement
Method for Aero-Engine Oil Debris Based on Improved Variational Mode
Decomposition Denoising
Authors: Tong Liu, Hanlin Sheng, Zhaosheng Jin, Li Ding, Qian Chen, Rui Huang, Shengyi Liu, Jiacheng Li, Bingxiong Yin
First page: 826
Abstract: This paper presents an effective method for measuring oil debris with high confidence to ensure the wear monitoring of aero-engines, which suffers from severe noise interference, weak signal characteristics, and false detection. First, an improved variational mode decomposition algorithm is proposed, which combines wavelet transform and interval threshold processing to suppress the complex noise interference on the signal. Then, a long-short-term memory neural network with deep scattering spectrum preprocessing is used to identify the signal characteristics under the multi-resolution analysis framework. The optimal hyperparameters are automatically configured using Bayesian optimization to solve the problem of weak, distorted, and hard-to-extract signal characteristics. Finally, a detection algorithm based on multi-window fusion judgment is applied to improve the confidence of the detection process, reduce the false detection and false alarm rate, and calculate the debris size information according to the sensor principle. The experimental results show that the proposed method can extract debris signals from noise with a signal-to-noise ratio improvement of more than 9 dB, achieve a high recognition accuracy of 99.76% with a missed detection rate of 0.24%, and output size information of debris to meet the need for aero-engine oil debris measurement.
Citation: Aerospace
PubDate: 2023-09-22
DOI: 10.3390/aerospace10100826
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 827: A Pattern Search Method to Optimize Mars
Exploration Trajectories
Authors: Su-Jin Choi, Hongjae Kang, Keejoo Lee, Sejin Kwon
First page: 827
Abstract: The Korean National Space Council recently released “Mars Exploration 2045” as part of its future strategic plan. The operations for a Mars explorer can be defined based on domestically available capabilities, such as ground operations, launch, in-space transport and deep space link. Accordingly, all of our exploration scenarios start from the Naro space center, and the pathway to Mars is optimized using an objective function that minimizes the required ∆V. In addition, the entire phase of Mars orbit insertion should remain in contact with our deep space antennas, a measure that is imposed as an operational constraint. In this study, a pattern search method is adopted, as it can handle a nonlinear problem without relying on the derivatives of the objective function, and optimal trajectories are generated on a daily basis for a 15-day launch period. The robustness of this direct search method is confirmed by consistently converged solutions showing, in particular, that the ascending departure requires slightly less ∆V than the descending departure on the order of 10 m/s. Subsequently, mass estimates are made for a Mars orbiter and a kick stage to determine if the desired ∆V is achievable with our eco-friendly in-space propulsion system when launched from our indigenous launch vehicle, KSLV-II.
Citation: Aerospace
PubDate: 2023-09-22
DOI: 10.3390/aerospace10100827
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 828: Structural Optimization of AerMet100 Steel
Torsion Spring Based on Strain Fatigue
Authors: Meng Wang, Hongen Li, Hu Chen, Xingbo Fang, Enze Zhu, Pujiang Huang, Xiaohui Wei, Hong Nie
First page: 828
Abstract: The torsion spring of a carrier-based aircraft landing gear is a key component, which is normally manufactured out of AerMet100 ultra-high-strength steel. The takeoff and landing performance is greatly influenced by its bearing capacity and structural durability. To carry out the structure anti-fatigue design, it is necessary to investigate the influence of the spring structure features on its fatigue life, based on which the strain fatigue analysis and parameter optimization design of the torsion spring are executed. Through the finite element analysis conducted with ABAQUS, it was determined that there exists serious stress concentration in the relief groove. Based on the theory of strain fatigue, the fatigue life of the torsion spring was obtained, and the fracture position and lifecycle were consistent with the test results. A structure optimization platform based on a parametric method was established. Samples were selected through the DOE (design of experiment), and a surrogate model was established based on RBF (radial basis functions), followed by optimization using MIGA (multi-island genetic algorithms). With the parameter optimization of the relief groove, the structure was reconstituted and reanalyzed. From the simulation results, the peak strain was reduced by 30.7%, while the fatigue life was increased by 86.2% under the same loads and constraints. Moreover, laboratory tests were performed on the torsion spring after reconstruction, which showed that the fatigue life increases by 85.6% after optimization. The method presented in this paper can provide theoretical support and technical guidance for the application and structural optimization of ultra-high-strength steel structures.
Citation: Aerospace
PubDate: 2023-09-22
DOI: 10.3390/aerospace10100828
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 829: Study on the Aerothermoelastic
Characteristics of a Body Flap Considering the Nozzle–Jet
Interference
Authors: Ruhao Hua, Qi Chen, Zhao Wan, Hao Chen
First page: 829
Abstract: A body flap/RCS-integrated configuration is often used to achieve pitch trimming and controlled flight in near space for hypersonic vehicles. Under the high temperature and pressure load induced by the expansion wave at the nozzle exit, the body flap is prone to significant structural deformation, which leads to a change in the resulting moment, even comparable to the control ability, and bring additional challenges to the control system. Based on the CFD/CTD/CSD coupling method, the aerothermoelastic effect on the aerodynamic characteristics and structural deformation of the body flap under jet interaction is systematically studied. Numerical results indicate that the pitching moment coefficients show an increasing trend for all the models, rigid, elastic and thermoelastic, while the increment significantly decreases with the increase in trajectory altitudes. With the increase in deflection angle, the pitching moment coefficients of the three models decrease nonlinearly at high altitude, and the aerothermoelastic effect significantly decreases. At a middle-lower altitudes, the pitching moment coefficient is reversed at a lager deflection angle, and the trailing edge of the body flap presents the deformation characteristics of upward bending, which makes the aerothermoelastic phenomenon degenerate into an aeroelastic problem. From the station along the chord and spanwise direction, the change in displacement increment of the thermoelastic model reflects the competitive relationship between normal stress and thermal stress imposed by jet interaction.
Citation: Aerospace
PubDate: 2023-09-23
DOI: 10.3390/aerospace10100829
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 830: Multi-Domain Network Slicing in
Satellite–Terrestrial Integrated Networks: A Multi-Sided
Ascending-Price Auction Approach
Authors: Weiwei Jiang, Yafeng Zhan, Xiaolong Xiao
First page: 830
Abstract: With the growing demand for massive access and data transmission requests, terrestrial communication systems are inefficient in providing satisfactory services. Compared with terrestrial communication networks, satellite communication networks have the advantages of wide coverage and support for massive access services. Satellite–terrestrial integrated networks are indispensable parts of future B5G/6G networks. Challenges arise for implementing and operating a successful satellite–terrestrial integrated network, including differentiated user requirements, infrastructure compatibility, limited resource constraints, and service provider incentives. In order to support diversified services, a multi-domain network slicing approach is proposed in this study, in which network resources from both terrestrial and satellite networks are combined to build alternative routes when serving the same slice request as virtual private networks. To improve the utilization efficiency of limited resources, slice admission control is formulated as a mechanism design problem. To encourage participation and cooperation among different service providers, a multi-sided ascending-price auction mechanism is further proposed as a game theory-based solution for slice admission control and resource allocation, in which multiple strategic service providers maximize their own utilities by trading bandwidth resources. The proposed auction mechanism is proven to be strongly budget-balanced, individually rational, and obviously truthful. To validate the effectiveness of the proposed approach, real-world historical traffic data are used in the simulation experiments and the results show that the proposed approach is asymptotically optimal with the increase in users and competitive with the polynomial-time optimal trade mechanism, in terms of admission ratio and service provider profit.
Citation: Aerospace
PubDate: 2023-09-23
DOI: 10.3390/aerospace10100830
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 831: Aerodynamic Robust Design Research Using
Adjoint-Based Optimization under Operating Uncertainties
Authors: Yuhang Ma, Jiecheng Du, Tihao Yang, Yayun Shi, Libo Wang, Wei Wang
First page: 831
Abstract: Robust optimization design (ROD) is playing an increasingly significant role in aerodynamic shape optimization and aircraft design. However, an efficient ROD framework that couples uncertainty quantification (UQ) and a powerful optimization algorithm for three-dimensional configurations is lacking. In addition, it is very important to reveal the maintenance mechanism of aerodynamic robustness from the design viewpoint. This paper first combines gradient-based optimization using the discrete adjoint-based approach with the polynomial chaos expansion (PCE) method to establish the ROD framework. A flying-wing configuration is optimized using deterministic optimization and ROD methods, respectively. The uncertainty parameters are Mach and the angle of attack. The ROD framework with the mean as an objective achieves better robustness with a lower mean (6.7% reduction) and standard derivation (Std, 18.92% reduction) compared to deterministic results. Moreover, we only sacrifice a minor amount of the aerodynamic performance (an increment of 0.64 counts in the drag coefficient). In comparison, the ROD with Std as an objective obtains a very different result, achieving the lowest Std and largest mean The far-field drag decomposition method is applied to compute the statistical moment variation of drag components and reveal how the ROD framework adjusts the drag component to realize better aerodynamic robustness. The ROD with the mean as the objective decreases the statistical moment of each drag component to improve aerodynamic robustness. In contrast, the ROD with Std as an objective reduces Std significantly by maintaining the inverse correlation relationship between the induced drag and viscous drag with an uncertainty parameter, respectively. The established ROD framework can be applied to future engineering applications that consider uncertainties. The unveiled mechanism for maintaining aerodynamic robustness will help designers understand ROD results more deeply, enabling them to reasonably construct ROD optimization problems.
Citation: Aerospace
PubDate: 2023-09-24
DOI: 10.3390/aerospace10100831
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 832: Thermal Decomposition of Ammonium
Dinitramide (ADN) as Green Energy Source for Space Propulsion
Authors: Zakaria Harimech, Kainaubek Toshtay, Meiram Atamanov, Seitkhan Azat, Rachid Amrousse
First page: 832
Abstract: The thermal decomposition of an ammonium dinitramide-based energetic compound was conducted for the first time using a dispersive inductively coupled plasma mass spectrometer, DTA-TG analysis, and pyrolysis at a constant temperature. A liquid droplet was injected over synthesized CuO catalytic particles deposited on lanthanum oxide-doped alumina. The thermal behavior of the ADN liquid monopropellant revealed that decomposition in the presence of catalytic particles occurs in two distinct steps, with the majority of ejected gases being detected in real-time analysis using the DIP-MS technique. At a temperature of 280 °C, pyrolysis confirmed the catalytic decomposition behavior of ADN, which occurred in two distinct steps.
Citation: Aerospace
PubDate: 2023-09-25
DOI: 10.3390/aerospace10100832
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 833: Effect of Refrigerated Inlet Cooling on
Greenhouse Gas Emissions for a 250 MW Class Gas Turbine Engine
Authors: Ali Dinc, Ali Mamedov, Ertugrul Tolga Duran, Fethi Abbassi, Ibrahim Elbadawy, Kaushik Nag, Mehdi Moayyedian, Mohamed Fayed, Murat Otkur, Yousef Gharbia
First page: 833
Abstract: In this study, the effect of inlet air cooling on greenhouse gas (GHG) emissions and engine performance for a land-based gas turbine engine was investigated under varying ambient temperatures (15–55 °C). The study aimed to reduce GHG emissions while improving output power and fuel efficiency during hot weather operating conditions. For illustrative purposes, a representative gas turbine engine model, approximating the 250 MW class General Electric (GE) engine, was analyzed in a simple cycle. A refrigeration process was integrated with a turboshaft gas turbine engine to chill the incoming air, and the power required for cooling was extracted from the gas turbine’s output power. This mechanical chiller was assumed to provide a 15 °C inlet air temperature. Without inlet air cooling, at 55 °C ambient temperature, the engine’s power output was calculated to decrease by 15.06%, while power-specific fuel consumption and GHG emissions increased by 6.09% and 5.84%, respectively. However, activating the refrigeration or cooling system in the inlet made it possible to mitigate most of the adverse effects of hot weather on the engine’s performance and GHG emissions. Therefore, with inlet air cooling, the power output loss reduces to 3.28%, indicating an 11.78% recovery compared to the 15.06% loss without cooling. Similarly, the rise in power-specific fuel consumption caused by high ambient temperature decreases from 6.09% to 3.43%, reflecting a 2.66% improvement. An important finding of the study is that with inlet air cooling, the increase in GHG emissions reduces from 5.84% to 3.41%, signifying a 2.43% improvement on a hot day with a temperature of 55 °C.
Citation: Aerospace
PubDate: 2023-09-25
DOI: 10.3390/aerospace10100833
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 834: Study on the Glider Soaring Strategy in
Random Location Thermal Updraft via Reinforcement Learning
Authors: Yunxiang Cui, De Yan, Zhiqiang Wan
First page: 834
Abstract: Soaring birds can use thermal updrafts in natural environments to fly for long periods or distances. The flight strategy of soaring birds can be implemented to gliders to increase their flight time. Currently, studies on soaring flight strategies focus on the turbulent nature of updrafts while neglecting the random characteristics of its generation and disappearance. In addition, most flight strategies only focus on utilizing updrafts while neglecting how to explore it. Therefore, in this paper, a complete flight strategy that seeks and uses random location thermal updrafts is mainly emphasized and developed. Moreover, through the derivation of flight dynamics and related formulas, the principle of gliders acquiring energy from thermal updrafts is explained through energy concepts. This concept lays a theoretical foundation for research on soaring flight strategies. Furthermore, the method of reinforcement learning is adopted, and a perception strategy suitable for gliders that considers the vertical ground speed, vertical ground speed change rate, heading angle, and heading angle change as the main perception factors is developed. Meanwhile, an area exploring strategy was trained by reinforcement learning, and the two strategies were combined into a complete flight strategy that seeks and uses updrafts. Finally, based on the guidance of the soaring strategy, the flight of the glider in the simulation environment is tested. The soaring strategy is verified to significantly improve the flight time lengths of gliders.
Citation: Aerospace
PubDate: 2023-09-25
DOI: 10.3390/aerospace10100834
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 835: Impact of Higher Airspace Operations on Air
Traffic in Europe
Authors: Oliver Pohling, Lorenz Losensky, Sandro Lorenz, Sven Kaltenhäuser
First page: 835
Abstract: Historically, higher airspace has been used for military exercises and as transit for space vehicles. Riding on commercial space operations’ coattails, more and more vehicles are under development that will make use of higher airspace resources. This will lead to increasing interactions with conventional air traffic since these new vehicles will have to transit through lower airspaces. The management of these operations is necessary to ensure the safe and practicable shared usage of these airspaces. This paper outlines an assessment of the impact of higher airspace operations on conventional air traffic in Europe. Initially, a synthesis of possible use cases was performed, and demand scenarios were developed that served as input to a fast-time simulation. The impact on air traffic was measured by means of flight efficiency parameters. The simulation results showed that the impact is dependent on the type of operation. High-altitude platform system flights and orbital launches cause the largest deviations in flight distance, flight duration and fuel consumption. Higher airspace operation parameters, including location, time, and duration, strongly affect the impact on the conventional air traffic.
Citation: Aerospace
PubDate: 2023-09-25
DOI: 10.3390/aerospace10100835
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 836: Base Flow and Drag Characteristics of a
Supersonic Vehicle with Cold and Hot Jet Flows of Nozzles
Authors: Yongchan Kim, Junyeop Nam, Tae-Seong Roh, Hyoung Jin Lee
First page: 836
Abstract: Base drag has a significant effect on the overall drag of a projectile in a supersonic flow. Herein, the base drag and flow characteristics of cold and hot gas flow in a supersonic flow are analyzed via numerical simulations. The hot gas flow is simulated using a chemical equilibrium application code based on hydrogen combustion. Two types of nozzle configurations, namely conical and contoured, are chosen for the simulation. The simulation results reveal that the change in base drag is 5–85% according to the injection gases. In the over-expanded and slightly under-expanded conditions, the base drag decreases in the hot gas flow, owing to the weak expansion fan caused by the high-temperature nozzle flow expansion, whereas in the highly under-expanded condition, the base drag decreases, owing to the strong shock wave near the base caused by the deflection of the recirculation region toward the body wall. In addition, the variations in base flow structures are observed differently compared with the cold flow; for example, a weak oblique shock wave at the nozzle exit, an increase in the distance between the shock wave and base, and deflection of the recirculation region based on the body wall are observed.
Citation: Aerospace
PubDate: 2023-09-25
DOI: 10.3390/aerospace10100836
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 837: An Aerodynamic Correction Technique for the
Unsteady Subsonic Wing–Body Interference Model
Authors: Kun Mao, Wuxing Jing, Meihong Zhang, Huining Zhang
First page: 837
Abstract: This paper investigates a novel correction technique for the unsteady subsonic wing–body interference model. The correction technique considers the unsteady forces on the lifting boxes and the body elements of an idealized aircraft model. The chosen simulation model was a passenger aircraft, and the transonic unsteady aerodynamics in sinusoidal pitch motion at four different frequencies are analyzed. The unsteady aerodynamics of the uncorrected DLM (doublet lattice method), ECFT (enhanced correction factor technique) and the new unsteady wing–body correction method are compared to the unsteady CFD simulation results. The results show that when the frequency is small, the new unsteady wing–body correction method can obtain certain benefits in terms of accuracy, for the lifting boxes and the body elements as well.
Citation: Aerospace
PubDate: 2023-09-26
DOI: 10.3390/aerospace10100837
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 838: Two-Dimensional Geometrical Shock Dynamics
for Blast Wave Propagation and Post-Shock Flow Effects
Authors: Heng Liu, Veronica Eliasson
First page: 838
Abstract: Geometrical shock dynamics (GSD) is a model capable of efficiently predicting the position, shape, and strength of a shock wave. Compared to the traditional Euler method that solves the inviscid Euler equations, GSD is a reduced-order model derived from the method of characteristics which results in a more computationally efficient approach since it only considers the motion of the shock front instead of the entire flow field. Here, a study of post-shock flow effects in two dimensions has been performed. These post-shock flow effects become increasingly important when modeling blast wave propagation over extended times or distances, i.e., a shock front that decays in speed and that has decaying properties behind it. A comparison between the first-order complete, fully complete and point-source GSD (PGSD) models reveals the importance of preserving an intact post-shock flow term, which is truncated by the original GSD model, in predicting blast motion. Lagrangian simulations were performed for the case of interaction between two cylindrical blast waves and the results were compared to prior experimental work. The results showed an agreement in attenuation of the maximum pressure at the Mach stem, but an overestimation of the Mach stem growth at its early stage was observed using PGSD. To address this issue, another model was developed that combines the PGSD model with shock–shock approximate theory (PGSDSS), but it excessively attenuates Mach stem evolution.
Citation: Aerospace
PubDate: 2023-09-26
DOI: 10.3390/aerospace10100838
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 839: Numerical Simulation of Chemical Propulsion
Systems: Survey and Fundamental Mathematical Modeling Approach
Authors: Jihyoung Cha
First page: 839
Abstract: This study deals with the mathematical modeling and numerical simulation of chemical propulsion systems (CPSs). For this, we investigate and summarize a comprehensive collection of the simulation modeling developments of CPSs in academic works, applications, and industrial fields. Then, we organize and analyze the simulation modeling approaches in several ways. After that, we organize differential-algebraic Equations (DAEs) for fundamental mathematical modeling consisting of the governing Equations (ordinary differential equations, ODEs) for the components and other equations derived from several physical rules or characteristics (algebraic equations or phenomenological equations, AEs) and then synthesize and summarize the fundamental structures of analytic mathematical modeling by types (liquid-propellant rocket engines, solid-propellant rocket motors, and hybrid-propellant rocket motors) of CPSs.
Citation: Aerospace
PubDate: 2023-09-26
DOI: 10.3390/aerospace10100839
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 840: Decentralized Differential Aerodynamic
Control of Microsatellites Formation with Sunlight Reflectors
Authors: Kirill Chernov, Uliana Monakhova, Yaroslav Mashtakov, Shamil Biktimirov, Dmitry Pritykin, Danil Ivanov
First page: 840
Abstract: The paper presents a study of decentralized control for a satellite formation flying mission that uses differential lift and drag to enforce the relative positioning requirements. All spacecraft are equipped with large sunlight reflectors so that, given the appropriate lighting conditions, the formation as a whole can be made visible from the Earth as a configurable pixel image in the sky. The paper analyzes the possibility of achieving a pre-defined lineup of the formation by implementing decentralized aerodynamic-based control through the orientation of sunlight reflectors relative to the incoming airflow. The required relative trajectories are so-called projected circular orbits which ensure the rotation of the image with the orbital period. The choice of the reference trajectory for each satellite is obtained by minimizing the total sum of relative trajectory residuals. The control law is based on the linear-quadratic regulator with the decentralized objective function of reducing the mean deviation of each satellite’s trajectory relative to the other satellites. The accuracy of the required image construction and convergence time depending on the initial conditions and orbit altitude are studied in the paper.
Citation: Aerospace
PubDate: 2023-09-26
DOI: 10.3390/aerospace10100840
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 841: In-Vehicle Speech Recognition for
Voice-Driven UAV Control in a Collaborative Environment of MAV and UAV
Authors: Jeong-Sik Park, Na Geng
First page: 841
Abstract: Most conventional speech recognition systems have mainly concentrated on voice-driven control of personal user devices such as smartphones. Therefore, a speech recognition system used in a special environment needs to be developed in consideration of the environment. In this study, a speech recognition framework for voice-driven control of unmanned aerial vehicles (UAVs) is proposed in a collaborative environment between manned aerial vehicles (MAVs) and UAVs, where multiple MAVs and UAVs fly together, and pilots on board MAVs control multiple UAVs with their voices. Standard speech recognition systems consist of several modules, including front-end, recognition, and post-processing. Among them, this study focuses on recognition and post-processing modules in terms of in-vehicle speech recognition. In order to stably control UAVs via voice, it is necessary to handle the environmental conditions of the UAVs carefully. First, we define control commands that the MAV pilot delivers to UAVs and construct training data. Next, for the recognition module, we investigate an acoustic model suitable for the characteristics of the UAV control commands and the UAV system with hardware resource constraints. Finally, two approaches are proposed for post-processing: grammar network-based syntax analysis and transaction-based semantic analysis. For evaluation, we developed a speech recognition system in a collaborative simulation environment between a MAV and an UAV and successfully verified the validity of each module. As a result of recognition experiments of connected words consisting of two to five words, the recognition rates of hidden Markov model (HMM) and deep neural network (DNN)-based acoustic models were 98.2% and 98.4%, respectively. However, in terms of computational amount, the HMM model was about 100 times more efficient than DNN. In addition, the relative improvement in error rate with the proposed post-processing was about 65%.
Citation: Aerospace
PubDate: 2023-09-27
DOI: 10.3390/aerospace10100841
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 842: A Unified Numerical Approach to the
Dynamics of Beams with Longitudinally Varying Cross-Sections, Materials,
Foundations, and Loads Using Chebyshev Spectral Approximation
Authors: Haizhou Liu, Yixin Huang, Yang Zhao
First page: 842
Abstract: Structures with inhomogeneous materials, non-uniform cross-sections, non-uniform supports, and subject to non-uniform loads are increasingly common in aerospace applications. This paper presents a simple and unified numerical dynamics model for all beams with arbitrarily axially varying cross-sections, materials, foundations, loads, and general boundary conditions. These spatially varying properties are all approximated by high-order Chebyshev expansions, and discretized by Gauss–Lobatto sampling. The discrete governing equation of non-uniform axially functionally graded beams resting on variable Winkler–Pasternak foundations subjected to non-uniformly distributed loads is derived based on the Euler–Bernoulli beam theory. A projection matrix method is employed to simultaneously assemble spectral elements and impose general boundary conditions. Numerical experiments are performed to validate the proposed method, considering different inhomogeneous materials, boundary conditions, foundations, cross-sections, and loads. The results are compared with those reported in the literature and obtained by the finite element method, and excellent agreement is observed. The convergence, accuracy, and efficiency of the proposed method are demonstrated.
Citation: Aerospace
PubDate: 2023-09-27
DOI: 10.3390/aerospace10100842
Issue No: Vol. 10, No. 10 (2023)
- Aerospace, Vol. 10, Pages 843: An Enhanced Incremental Nonlinear Dynamic
Inversion Control Strategy for Advanced Unmanned Aircraft Systems
Authors: Maryam Taherinezhad, Alejandro Ramirez-Serrano
First page: 843
Abstract: A cascade control architecture was proposed for the control of advanced unmanned aerial vehicles targeted for operation inside confined hazardous spaces. The aircraft of interest is a highly maneuverable system presenting highly coupled dynamics, enabling it to perform unique flight maneuvers that no other aircraft can. To deal with the complexities inherent to such an aircraft, a novel nonlinear control architecture was proposed. Two outer loop NDI controllers and an inner loop INDI controller were employed for position/velocity and attitude/rotation rate control, respectively. These controllers assist each other, enabling them to decouple the aircraft dynamics while coping with complex external disturbances. The obtained results demonstrate an effective control of the targeted aircraft system to accurately track complex flight maneuvers.
Citation: Aerospace
PubDate: 2023-09-27
DOI: 10.3390/aerospace10100843
Issue No: Vol. 10, No. 10 (2023)
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