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Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering
Journal Prestige (SJR): 0.422
Citation Impact (citeScore): 1
Number of Followers: 42  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0954-4100 - ISSN (Online) 2041-3025
Published by Sage Publications Homepage  [1176 journals]
  • Study on the combined influence of aerodynamic sweep and casing treatment
           in a transonic compressor rotor

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      Authors: Zhidong Chi, Wuli Chu, Haoguang Zhang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Casing treatment and three-dimensional blade design are effective techniques to remedy the deficiency of compressor stability margin, yet their combined effects on compressor performance are seldom studied. With the help of URANS simulations, this paper explored the combined influence of aerodynamic sweep and casing treatment in a transonic compressor rotor. Compared with the configurations of single sweep and single casing treatment, the combined configuration presented an outstanding advantage for improving compressor performance. For compressor overall performance, the stall margin improvement of combined configuration was up to 11.8%, larger than single forward sweep and single casing treatment. Meanwhile, peak efficiency penalty of combined configuration (−1.02%) was significantly lower than that of single casing treatment. Under the effect of casing treatment, the results showed that the pulsating axial velocity could effectively delay the interface of the tip leakage flow and main flow, preventing the overflow of tip leakage flow. The distributions of blockage coefficient and loading coefficient indicated that combined configuration was more effective due to tip unload by casing treatment and blockage resistance ability by forward sweep. Furthermore, the spatial and temporal evolutions of axial velocity at slot opening surface were discussed in detail. Compared with the single casing treatment, higher positive axial velocity excitation and smaller range of negative axial velocity were introduced by combined configuration, which contributed to better stability enhancement.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-09-27T12:14:51Z
      DOI: 10.1177/09544100231203409
       
  • Optimal leading-edge deflection for flapping airfoil propulsion

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      Authors: Emanuel A.R. Camacho, André R.R. Silva, Flávio D. Marques
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The aerodynamics of oscillating airfoils are crucial to understanding subjects such as rotor dynamics and bio-inspired flows. Unsteady airfoils have been studied extensively, but there is an overall lack of knowledge regarding newer and more complex kinematics. The present paper builds upon our modified version of the NACA0012 by numerically comparing its way of flapping with the standard flapping that is common in the literature. The comparison is conducted parametrically at a Reynolds number of 104 for two nondimensional amplitudes. Then, using a gradient-based optimization method, we search for pitching amplitudes that maximize the propulsive power and efficiency for both flapping modes. Results indicate that the proposed flapping methodology is more promising than conventional flapping, with thrust increases up to approximately 40%. Furthermore, the proposed mechanism achieves maximum propulsive power with near-optimal efficiency, a common limitation of traditional flapping airfoils.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-09-26T10:25:40Z
      DOI: 10.1177/09544100231201553
       
  • Numerical investigation of store separation from cavity problems at high
           speeds

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      Authors: Saleh Abuhanieh, Hasan U. Akay
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      In this work, the ability of open-source CFD tools to conduct store separation simulations from cavities is evaluated and validated using a generic test case from the literature. Firstly, the ability and accuracy of these tools for solving cavity flows at high speeds are evaluated. Secondly, their competence in predicting the trajectory of a generic store from a generic deep cavity is checked. Finally, and in order to reduce the associated computational costs, a release-time dependability factor from the recent literature is studied and evaluated. The obtained results using the selected open-source CFD tools matched quite well with the wind tunnel results. Furthermore, the results show that predicting the release-time dependability using a quantified index/factor can be a potential remedy for reducing the computational cost for this type of CFD simulations.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-09-21T05:11:02Z
      DOI: 10.1177/09544100231203404
       
  • Estimation of aerodynamic parameters using neural artificial bee colony
           fusion algorithm for moderate angle of attack using real flight data

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      Authors: Prashant Kumar, Sarvesh Kumar Sonkar, Riya Catherine George, Ajoy Kanti Ghosh, Deepu Philip
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Aircraft system identification aims to estimate the aerodynamic force and moment coefficients utilizing intelligent modeling and parametric identification methodologies. Classical methods like output, filter, and equation error methods apply extensively as parametric approaches. In contrast, machine learning approaches like Artificial Neural Networks (ANN), Adaptive Neuro-Fuzzy Inference Systems (ANFIS), etc., are alternatives to model-based methods. This work presents a novel aerodynamic parameters estimation technique that fuses two biologically inspired optimization techniques, (i) the Artificial Bee Colony (ABC) optimization and (ii) ANN for an actual aircraft while incorporating system and measurement uncertainty. The fusion of ABC and ANN imparts the ability to address sensor noise challenges associated with system identification and parameter estimation. Comparison of the proposed method’s results with the benchmark techniques like Least Square, Filter Error, and Neural Gauss Methods using recorded flight data of the ATTAS (DLR German Aerospace Centre) and HANSA-3 (IIT Kanpur) aircrafts established its adequacy and efficacy. Furthermore, the capability of the proposed hybrid method to extract stability and control variables from the stable aircraft kinematics is shown even with insufficient information in its data history.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-09-20T12:49:16Z
      DOI: 10.1177/09544100231201215
       
  • ANN_ITU: Predicting rain attenuation with a hybrid model for earth-space
           links

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      Authors: Dongyu Xu, Zhaodi Wang, Biao Leng
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Rain attenuation prediction of earth-space links is of vital significance for the application and development of satellite communication. Recently, most rain attenuation prediction methods are based on semi-empirical models or data-driven models, the former suffering from incompleteness problem, the latter faced with limited performance due to scarce data. In order to realize higher rain attenuation prediction performance, we propose a novel hybrid model ANN_ITU that combines advantages of the semi-empirical model and the artificial neural network. In ANN_ITU framework, the semi-empirical model ITU-R P.618-12 is leveraged to predict rain attenuation, and a six-layer artificial neural network is utilized to correct the rain attenuation predicted by ITU-R P.618-12, thus generating the final rain attenuation value. What’s more, we also present theories of two machine-learning based rain attenuation prediction methods, namely, random forest and support vector regression. Last but not least, we expound on processes of DBSG3 dataset filtering and data preprocessing. Experiments on DBSG3 dataset are carried out. Experimental results demonstrate that the hybrid ANN_ITU algorithm outperforms purely semi-empirical algorithms and data-driven algorithms. The evaluation indexes mean value, standard deviation, and root mean square value are 0.0355%, 19.63%, and 19.63%, respectively, which prove the effectiveness and precision of our rain attenuation prediction model ANN_ITU.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-09-20T10:24:32Z
      DOI: 10.1177/09544100231202930
       
  • Aerothermodynamic analysis and rear wake assessment of shock wave
           interference over blunt leading edge at Mach 6.5

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      Authors: Gaurav Shivpratap Singh, Chirag Sharma, Siddhant Swaroop Padhy, Deepu Dinesan, Bibin John
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      A detailed numerical study of shock-wave interference on a cylindrical blunt leading edge in hypersonic flow is carried out to reveal the effect of shock-shock interaction on peak heating and blunt body aerodynamics. This study is unique in that it examines the effect of interactions on rear wake formation and aerodynamic forces acting on the blunt body. Six different shock wave interference patterns described by Edney are studied for a freestream Mach number of 6.5. Compressible Reynolds-averaged Navier–Stokes equations are solved using finite volume method to obtain accurate prediction of the flowfield and aerodynamic loads. Hugoniot jump conditions are imposed in the inlet boundary to realize oblique shock of desired strength to interact with the detached shock at specific location. Numerical predictions are in good agreement with reported experimental measurements. The results obtained in this study reveals that the type of shock-shock interaction pattern can significantly alter the characteristics of the rear wake. Comparisons to undisturbed flow conditions reveal that Type II to VI interactions lead to an increase in wake size, whereas Type I interaction shows a marginal reduction. These changes in wake size are attributed to modifications in the forebody boundary layer induced by the shock-shock interactions. In the case of Type I interaction, however, the transmitted wave interacting with the rear wake is found to be responsible for the marginal reduction in wake size. This study also shows that changes to the rear wake structure caused by the change in interaction type can affect aerodynamic loads. Type VI interaction recorded a maximum drag coefficient of 2.96, whereas Type IV interaction yielded a maximum lift coefficient of 0.992. These findings demonstrate the potential for dynamically adjusting the control forces of a flying body by manipulating shock interference.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-09-15T05:49:52Z
      DOI: 10.1177/09544100231199859
       
  • Effect of constraints and vertical wall interaction on workspace of a
           quadcopter manipulator system

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      Authors: Vidya Sumathy, Rakesh R Warier, Debasish Ghose
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The workspace analysis of a robotic arm coupled to an unmanned aerial vehicle executing close-to-target operations is significant. The workspace of a 3 degree-of-freedom manipulator mounted to the bottom of a quadcopter and having an extended workspace is analyzed in this research, along with a motion planning algorithm. The quadcopter manipulator system comprises a robotic arm attached to the quadcopter’s center of gravity at its bottom. The manipulator has an extended workspace as its end-effector can reach three-dimensional locations above and below the drone’s airframe. The arm’s workspace is determined by system kinematics. Certain factors like downwash from the drone, the robotic arm’s singularity, servo motor stall torques, and mechanical structure limit the arm’s workspace during real-time tasks. A detailed description of these factors and their impact on the arm’s reachable workspace is also provided. Based on these limitations, the motion planning algorithm verifies the viability of a specific arm configuration and, therefore, the feasibility of the task. A concept called the near-wall effect and strategies to limit its influence on aerial robots are presented to comprehend the effect of a wall on the system in tasks involving targets on a compound wall. The proposed research outcomes are evaluated using MATLAB and ROS/Gazebo simulations.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-09-07T11:04:03Z
      DOI: 10.1177/09544100231193133
       
  • Validation and analyses of QCR correction turbulence model in
           sub-/super-sonic inner flows

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      Authors: Gang Wang, Tianlai Gu, Shuai Zhang, Jifa Zhang, Yao Zheng
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The inlet, isolation section, and other internal flow components are important parts of the aircraft propulsion system. Their performances affect the stability of the entire propulsion system. According to those components, complicated shock wave/boundary layer interaction (SBLI), flow separation, and secondary flow phenomena would occur. The commonly used turbulence models, SA and SST, cannot predict the anisotropy of turbulence. This deficiency makes the calculated results differ significantly from the experimental results and cannot accurately predict their aerodynamic performance. This paper validates the feasibility and effectiveness of the turbulence models based on quadratic constitutive relation (QCR) correction applied to the flow of square duct, compression corners, diffusing 3D S-Duct, and axisymmetric cylindrical isolator. This can support future calculations of complex flow fields with flow separation and secondary flow phenomena in the subsonic or supersonic inlet. The results show that the turbulence model with QCR correction is better than the original turbulence model. Among them, the SA-QCR2020 turbulence model is the best, which is able to predict the presence of secondary flows and large boundary layer separated flows well.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-09-05T11:25:00Z
      DOI: 10.1177/09544100231199856
       
  • Regression-based identification and order reduction method for nonlinear
           dynamic structural models

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      Authors: Libao Wang, Min Xu
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      In this paper, we propose a regression-based nonlinear reduced-order model for nonlinear structural dynamics problems, called the Nonlinear Identification and Dimension-Order Reduction (NLIDOR) algorithm. We evaluate the algorithm using a simple toy model, a chain of coupled oscillators and an actual three-dimensional flat plate. The results show that NLIDOR can accurately identify the natural frequencies and modes of the system and capture the nonlinear dynamical features, while the linear Dynamic Mode Decomposition (DMD) method can only capture linear features and is influenced by nonlinear terms. Compared with the full-order model (FOM), NLIDOR can effectively reduce computational cost, while compared with DMD, NLIDOR significantly improves computational accuracy. The results demonstrate the effectiveness and potential of NLIDOR for solving nonlinear dynamic problems in various applications.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-09-01T02:31:30Z
      DOI: 10.1177/09544100231199239
       
  • Predicting pilot behavior during midair encounters using long short-term
           memory network

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      Authors: Yang Hu, Xiaoyan Wang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Characterized by the wide use of advanced automation and the introduction of new operation concepts, the future air transportation system will be more complex. Advanced pilot behavior models with improved capability are required to support the design and analysis of the midair encounter situations in the future air transportation system. This paper first filters midair encounter data from Automatic Dependent Surveillance-Broadcast (ADS-B) observations. Based on the acquired midair encounter data, a comprehensive pilot behavior model is proposed based on a multi-layer Long Short-Term Memory (LSTM) network. The model is designed for the purpose of enhancing the predicting capability of pilot behaviors in both horizontal and vertical planes. Finally, the performance of the proposed model to predict pilot behavior in both horizontal and vertical planes is studied through evaluating against realistic midair encounter situations.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-30T07:08:01Z
      DOI: 10.1177/09544100231198150
       
  • Reliability-based multidisciplinary design optimization of an aeroelastic
           unpowered guided aerial vehicle

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      Authors: Seid H Pourtakdoust, Amir H Khodabakhsh
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Most Aeronautical and Astronautical Systems (AAS) are inherently complex, multidisciplinary, nonlinear, and computationally intensive for design and analysis. Utilizing the Reliability-Based Multidisciplinary Design Optimization framework can address the multidisciplinary nature of these systems while accounting for inherent uncertainties. In this paper, an efficient methodology for Reliability-Based Multidisciplinary Design optimization of an aerial vehicle is developed. The computational burden of reliability assessment could make its integration within a Multidisciplinary Design Optimization cycle a formidable task. In this respect, a multilevel Multidisciplinary Design Optimization architecture is proposed in which the computational cost is reduced by considering the reliability analysis, as needed only for critical subsystems. To this end, a single-level Reliability-Based Multidisciplinary Design Optimization is derived using the Performance Measure Analysis and the Karush-Kuhn-Tucker condition. The work demonstrates the integration of this formulation into the proposed multilevel Reliability-Based Multidisciplinary Design Optimization architecture. The proposed design architecture is implemented for an aeroelastic Unpowered Guided Aerial Vehicle whose outcomes are compared with previous results obtained via a mono-level Uncertainty-Based Multidisciplinary Design Optimization architecture.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-29T08:24:18Z
      DOI: 10.1177/09544100231198160
       
  • Hardware-in-the-loop based ground test system for space berthing and
           docking mechanism of small spacecraft

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      Authors: Yaqiang Wei, Xiao Yang, Xinlin Bai, Zhigang Xu
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Ground test for space berthing and docking mechanism plays crucial roles in their stable operation in orbit. In this paper, a hardware-in-the-loop based ground test system is presented for economic reliability test for space berthing and docking mechanism of small spacecraft. In the system, the support and adapter unit is employed to fix the active part of the berthing and docking mechanism, and the end-effector of the manipulator connects the passive part. The manipulator is driven according to the relative motion calculated by the hardware-in-the-loop model after gravity compensation, to simulate motion of space berthing and docking mechanism in space. A Smith predictor is introduced for control system delays compensation. A berthing and docking mechanism was employed in the experiment to evaluate the performance of the test system. The results validated the effectiveness of the test system. Since only one manipulator is exploited in the test system, compared with existing systems using two manipulators, the system cost can be greatly decreased.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-28T03:28:55Z
      DOI: 10.1177/09544100231198152
       
  • Analysis of the convergent section of a C-D nozzle and its influence on
           airflow performance using evolutionary strategies

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      Authors: Jhan Jaider Bahamon Blanco
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The shape of a nozzle wall influences the phenomena associated with the behaviour of the fluid movement within the flow field mathematically described by the Navier—Stokes equations. This article studies different drawing techniques for the aerodynamic tracing of the wall contour searched by Vitoshinsky, Bell, Metha and Sivells. To the system of equations of the design models are added the math formulas that define Sauer’s method for redesigning the length of the converging section modifying simultaneously the contour sketches. The aim is to obtain a better distribution of the physical properties and to avoid excessive pressure in a limited space that could affect the internal structure of the wall. Numerical methods are used to visualize the features of the wave propagation, boundary layer separation and flow separation pattern to survey the appearance of the stream generated within the geometric profile of the wall and the ejected flow. A computational analysis is developed to make a comprehensive assessment of different chosen wall contours, including an optimized wall shape using genetic algorithms through a process to find maximum and minimum values of the cross-sectional area to change the wall layout. The selection carries out based on design parameters with variable area contraction ratio (from low to high) in the convergent section for being simulated in a boundary condition with a low-pressure ratio (NPR). Experimental data from Hunter's research are used for validation of the results for a J2-type aerospace nozzle operating at an NPR of 3.413.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-26T04:38:27Z
      DOI: 10.1177/09544100231197092
       
  • Design and characterizing of blower wind tunnel using experimental and
           numerical simulation

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      Authors: Itimad D J Azzawi
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      A new subsonic blower wind tunnel design has been studied both numerically and experimentally; it is also referred to as “blower” wind tunnel. This paper is initially aimed to address each sequential stage of the wind tunnel design process. Rather than applying the standard method of modelling solely the flow in the test section, a large-scale CFD model of the whole wind tunnel was employed. The loss of every constituent element was calculated and then all the losses are added up to determine the power needed for the wind tunnel operation which is used as “intake fan” boundary conditions in the CFD model. Then, flow uniformity and turbulent intensity measurements in an empty test section using a pitot static tube and hot wire anemometer (HWA) were introduced to validate the CFD results. The results showed that flow quality was significantly affected by flow conditioners (uniformity devices) (honeycomb and mesh screens) in the settling chamber and wide-angle diffuser. Investigations were also conducted to evaluate the flow deficit in the wake area behind a convex hump model using both HWA and particle image velocimetry PIV. This was additional experimental tests carried out to validate the suitability of the wind tunnel designed for aerodynamic research.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-22T04:54:46Z
      DOI: 10.1177/09544100231195190
       
  • Evaluation of generalized k-ω turbulence model in strong separated flow
           estimation of thrust optimized parabolic nozzle

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      Authors: Sina Afkhami, Nematollah Fouladi, Mahmoud PasandidehFard
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      One of the frequently reported defects of RANS-based turbulence models is overestimation of turbulent kinetic energy production in high speed separated flow problems, which causes significant prediction errors. The correct estimation of such flow in thrust optimized parabolic nozzles extremely depends upon the accurate prediction of the onset of flow separation. In this paper, firstly, the significant error of conventional RANS-based turbulence models is shown to predict the onset of flow separation in this type of nozzles. Then, the prediction accuracy is improved through the modification of the essential parameters of the generalized k-ω (GEKO) turbulence model. It was found that modifying the separation and mixing parameters of the GEKO model to realize the turbulent kinetic energy production resulted in the accurate prediction of onset of flow separation at the extensive range of nozzle pressure ratios. Using this modified model with new coefficients reduced the error of about 30% of the k-ω-sst model in estimating the onset of flow separation. Also, the nozzle pressure value at which the transition from free shock separation (FSS) to restricted shock separation (RSS) occurs is well predicted by this approach. After strengthening the turbulence model, the flow physics has been investigated with increasing and decreasing nozzle chamber pressure. The length of the separation shock and reflected shock waves which impose the presence of FSS or RSS patterns and transitional phenomena are discussed. Our new findings show that unlike the transition from FSS to RSS, the inverse transition from RSS to FSS did not depend on the length of the separation and reflective shocks.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-21T05:05:29Z
      DOI: 10.1177/09544100231195774
       
  • Multi-objective multidisciplinary design optimization of liquid-propellant
           engines thrust chamber based on a surrogate model

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      Authors: Hamid Reza Alimohammadi, Reza Aghaei-Togh
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The design of liquid-propellant engines (LPEs) has several challenges in setting the performance parameters. Accordingly, optimizing the design of a thrust chamber is of considerable importance that has been considered in several research projects. Previous research has focused on multidisciplinary design optimization (MDO). However, despite these efforts, the main issues remain. The present paper proposes a multi-objective multidisciplinary design optimization based on an efficient adaptive surrogate model of the thrust chamber to address these issues. The proposed method introduces a practical multidisciplinary optimization method based on an adaptive surrogate model that uses the moving least squares methodology, CCM, sensitivity analysis, and the elite multi-objective genetic algorithm (NSGAII). Due to the high importance of specific impulse and thrust-to-weight ratio, these two functions were used as target functions and in the NSGAII framework, the Pareto frontier was drawn for them. The proposed method is applied to a thrust-chamber engine test case. The results show that the target performance of the engine is improved, the specific impulse value is increased by 3.4 s, and the thrust-to-weight ratio is increased by 4%. These values represent significant advances in LPE engine design. The results obtained in this study indicate the potential of the proposed method in solving large-scale thrust-chamber design optimization problems.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-19T05:31:06Z
      DOI: 10.1177/09544100231182268
       
  • Mechanism of characteristic change of panel flutter caused by oblique
           shock impingement

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      Authors: Xianzong Meng, Kun Ye, Zhengyin Ye
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Compared to the shock-free condition, the weak shock impingement stabilizes the flexible panel, while the strong shock impingement leads to the early onset of panel flutter with a significant increase in flutter amplitude and frequency. However, the reason for this change by shock impingement remains unclear. The current research examines the mechanism of this change by an in-house code where the von Kármán’s large deflection plate theory is coupled with two-dimensional Euler equations. Compared to the shock-free condition, the oblique shock impingement leads to the change of local dynamic pressure on the panel as well as the static pressure differential across the panel. The analysis on the influence of these changes indicates that, on the one hand, the average dynamic pressure on the panel becomes larger than the shock-free condition, accelerating the onset of panel flutter. On the other hand, the change of the static pressure differential across the panel alters the coupling characteristic between different natural frequencies (modes) of the panel structure. The dynamic response of panel flutter under shock impingements is dominated by the coupling between the second and third modes instead of the first two modes for panel flutter under the shock-free condition. The combined effect of these two changes leads to the change of flutter characteristics of the panel under shock impingement. These findings provide valuable insights into the mechanism of shock-induced panel flutter.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-19T05:27:08Z
      DOI: 10.1177/09544100231195377
       
  • The modeling and cascade sliding mode control of a moving mass-actuated
           coaxial dual-rotor UAV

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      Authors: Wang Siling, Ji Sichen, Zhou Yang, Sun Hongyan
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      In this study, an attitude control scheme based on a three-track moving mass control mechanism is proposed to address the problems of the overcomplicated rotor components, low service life, and low reliability of coaxial dual-rotor unmanned air vehicles (UAV). The motion and aerodynamic models of a moving mass-actuated ducted coaxial dual-rotor UAV are derived. The rotational dynamic characteristics of a moving mass-actuated UAV (MAUAV) with different slider positions and mass ratios are analyzed. An attitude controller based on backstepping sliding mode control is designed to address the nonlinearity and uncertainty of the MAUAV rotation. Based on this, we developed a position controller using cascade sliding mode control. The simulation results demonstrate that the designed attitude controller can achieve a settling time of 1.438 s in the unit-step response and a steady-state error of less than 5% in the sinusoidal attitude-tracking experiment. Additionally, the designed position controller exhibited a better trajectory-tracking effect under different levels of gust disturbance than that of a linear quadratic regulator control-based position controller.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-18T07:11:28Z
      DOI: 10.1177/09544100231190604
       
  • Conceptual design of long-endurance small solar-powered unmanned aerial
           vehicle with multiple tilts and hovers

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      Authors: Xiao Cao, Li Liu, Jiahao Ge, Dun Yang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      This paper presents an overall scheme of a long-endurance small solar-powered convertible unmanned aerial vehicle (CUAV) that operates tilt-rotor for multiple hover tasks. First, a solar/battery hybrid energy strategy was proposed to comprehensively meet the requirements of CUAVs with long endurance and multiple hovers. The particular ability of the solar-powered fixed-wing unmanned aerial vehicle (UAV), pure battery-powered CUAV, and the proposed long-endurance solar-powered CUAV with multiple cruises and hovers were comparatively analyzed from an energy standpoint. Second, a suitable conceptual design method and process for small solar-powered CUAV was given, and the robustness of the designed CUAV was using three performance metrics under nominal conditions. The approach was then applied to design a 6.5 kg CUAV, which was initially tested in flight. Finally, the performance and application potential of the designed CUAV was evaluated with operating conditions, mission requirements, energy input, and perpetual flight capability.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-18T02:33:14Z
      DOI: 10.1177/09544100231181872
       
  • Development and evolution mechanism of streamwise vortex in an
           inward-turning inlet

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      Authors: Ziao Wang, Xuanan Xin, Ruoyu Chen, Renzhe Huang, Chen Kong, Juntao Chang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The three-dimensional flows in an inward-turning inlet were numerically investigated at different incoming flow conditions. When the incoming flow conditions change, the shock angle and the shock interaction form of the external compression wave change, and the development of the near-wall low-energy fluid and the streamwise vortex is also affected. The impingement of the shock wave leads to a sharp increase in the vorticity of the low kinetic energy fluid. Under the pressure gradient caused by the shock wave, the high-vorticity fluid migrates from the cowl to the ramp and entrains the mainstream fluid to form a streamwise vortex, for which the velocity gradient (∂v/∂y + ∂w/∂z) along the vortex axis can accurately determine the rotation direction and the Hopf bifurcation position. By considering high Reynolds number flows, the pressure gradient along the vortex axis is developed to estimate the simplified dilation term (velocity gradient) due to its ease of measurement. However, the pressure gradient (∂p/∂x) along the vortex axis can lead to bias when evaluating the cross-flow state of the streamwise vortex, with the shock wave structure and high-vorticity fluid leading to under- and overestimation, respectively. This study provides a theoretical basis for an accurate determination of the flow state of a streamwise vortex in an inward-turning inlet and thus lays the foundation for effective vortex control.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-18T02:15:40Z
      DOI: 10.1177/09544100231194882
       
  • Robust adaptive quadrotor position tracking control for uncertain and
           fault conditions

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      Authors: M Bugrahan Artuc, Ismail Bayezit
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The combination of nonlinear indirect and direct adaptive control with an active fault-tolerant framework is proposed in this paper for quadrotor position tracking control under uncertain and fault conditions. An inner loop direct model reference adaptive controller generates the required force while moving along the reference trajectory, while nonlinear indirect adaptive controller maintains the required attitude angles. Furthermore, for uncertain conditions, our proposed framework provides significantly stable characteristics. Otherwise, when a fault occurs at actuators or sensors, the quadrotor vehicle cannot guarantee global asymptotic stability. This study contributes to an active fault-tolerant control strategy for solving the complex position tracking problem using the adaptive two-stage Kalman filter (ATSKF). Based on the fault information, a fault compensation term is added to the control law to improve convergence and system robustness in the presence of uncertain and fault conditions. Finally, simulation results show satisfactory performance for quadrotor vehicle position tracking, even with actuator faults and uncertainties.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-14T08:00:48Z
      DOI: 10.1177/09544100231181869
       
  • Research on normal ice adhesion strength in icing wind tunnel

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      Authors: Yusong Wang, Ke Xiong, Chunling Zhu, Chengxiang Zhu, Rongyin Guo, Lei Chen
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Aircraft icing seriously jeopardizes flight safety. The design of aircraft anti-icing/de-icing systems requires a thorough understanding of the adhesion between the ice and the substrate. In this research, an experimental device that can be housed within a wing is designed and constructed. Simulation analysis of the interfacial stresses is performed, which reveals that increasing the load and the interface size led to a deterioration in the uniformity of stresses at the interface. In addition, the ice layer does not undergo cohesive damage during the tests. The normal ice adhesion strength is evaluated in an icing wind tunnel using the methodology outlined in this paper. Glaze ice exhibits an increase in normal adhesion strength at lower temperatures, whereas the trend is reversed for rime ice. The minimum adhesion strength occurs near the medium volume diameter (MVD) of 30 µm. Furthermore, the normal strength is significantly enhanced by increase in wind speed and surface roughness, as well as by surface painting. The adhesion strength of aluminum substrates to ice is greater compared to titanium and stainless steel. Compared to shear adhesion strength, normal adhesion strength is less sensitive to various influencing factors. The proposed experimental framework provides precise measurement of normal adhesion strength of impact ice in the icing wind tunnel.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-08T04:17:20Z
      DOI: 10.1177/09544100231189803
       
  • Pressure loss control in a rotor-stator cavity with inward throughflow

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      Authors: Xin Shen, Jun Liu, Pei Wang, Qiang Du, Guang Liu, Zengyan Lian
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The back cavity of a centrifugal impeller is a typical rotor-stator cavity system with centripetal inflow in small or medium-sized aeroengines. In this paper, the effectiveness of using the “vortex control hole” structure to control the pressure loss in such a cavity is studied with experiment and numerical simulation. Vortex control hole refers to the passage connecting the internal and external air flow of the cavity. It distributes on the stationary casing circumferentially with a well-designed angle to produce an opposite tangential velocity to the main flow, thus reducing the tangential velocity of the main flow in the cavity. By controlling the swirl ratio, the pressure loss at cavity outlet could be decreased. The rotating Reynolds number Reφ = 6 × 105∼2.4 × 106, and turbulence parameter λt = 0.21∼0.55. Since the mainstream velocity has no tangential component at the inlet, it is considered that the inlet swirl ratio β0 is 0. The numerical simulation results were compared with the experimental results. The flow structure, the distribution of the swirl ratio, and the static pressure loss at the outlet of the cavity under different secondary air stream rates will be given. The coupling mechanism between the secondary airflow and the main flow in the cavity and the mechanism of the secondary air stream reducing the pressure loss in the disc cavity will be analyzed.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-08-02T04:11:06Z
      DOI: 10.1177/09544100231191699
       
  • Polytopal approximation for thrust magnitude constraints in rocket
           trajectory optimization

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      Authors: Jiawei Wang, Ran Zhang, Huifeng Li
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      This paper proposes a linear programming approach for onboard optimization of rocket trajectories, motivated by the need for reliable and computationally efficient trajectory optimization methods in real-time applications. To reformulate rocket trajectory optimization problems within a linear programming framework, a polytopal approximation method is developed. The polytopal approximation method approximates the thrust magnitude constraint using a set of artificial variables and linear constraints. Compared with a state-of-the-art approximation method, the polytopal approximation method demonstrates a higher accuracy-to-size ratio, enabling rocket trajectory optimization problems to be cast into linear subproblems without significantly increasing problem sizes. As linear subproblems can be readily solved by linear programming solvers, the proposed trajectory optimization approach inherits the solver’s reliability and computational efficiency, making it potentially useful for critical onboard applications. An ascent trajectory optimization problem is provided as an illustrative example to demonstrate the effectiveness of the proposed linear programming approach.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-07-27T10:05:50Z
      DOI: 10.1177/09544100231189994
       
  • Investigation of the effects of flame surface development on the ignition
           mechanism of aero-engine combustors

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      Authors: Qun Zhang, Zixin Wang, Fuzheng Yang, Zhidi Wu, Fan Hu, Xiaoyan Wang, Yaohong Gao, Xiaoxi Ma
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Large eddy simulation was employed to simulate the effects of different vane angles of the primary and pilot stages on the ignition process of a combustor under normal temperature and pressure conditions. The simulation results of different vane angles of the pilot stage were then verified experimentally. Kernel initiation and flame propagation in the cases of ignition success and failure were analysed. It was found that in the ignition failure case, the flame kernels are confined to the downstream zones of the venturi and cannot propagate radially, and almost no negative displacement exists in the axial direction. However, in the ignition success case, sub-fire kernels are always present outside the radial boundary of the primary stage. Five ignition modes were finally proposed: (I1) typical ignition, (I2) relatively high-speed ignition, (I3) single-kernel alternating dominant, (I4) main kernel dominant, and (I5) dual-kernel dominant modes. Using high-speed photography, the flame shape changes and ignition characteristics in the cases of successful and failed ignition with different pilot-stage vane angles were investigated.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-07-27T08:31:34Z
      DOI: 10.1177/09544100231185226
       
  • Zero-sum differential game guidance law for missile interception
           engagement via neuro-dynamic programming

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      Authors: A-xing Xi, Yuan-li Cai, Yi-fan Deng, Hao-nan Jiang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      In this paper, for solving the nonlinear control problem of the missile intercepting the maneuvering target, a novel nonlinear zero-sum differential game guidance law is proposed via the neuro-dynamic programming approach. First, the continuous-time nonlinear differential game problem is transformed into solving the nonlinear Hamilton–Jacobi–Isaacs (HJI) equation. Then, a critic neural network is designed to solve the corresponding nonlinear HJI equation. An adaptive weight tuning law for the critic weights is proposed, where an additional term is added to ensure the stability of the closed-loop nonlinear system. Furthermore, the uniform ultimate boundedness of the closed-loop system and the critic NN weights estimation error are proved with the Lyapunov approach. Finally, some simulation results are presented to demonstrate the effectiveness of the proposed differential game guidance law for nonlinear interception.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-07-27T08:23:25Z
      DOI: 10.1177/09544100231191411
       
  • Integrated fire/flight control coupler design for armed helicopters based
           on improved non-monotone adaptive trust region algorithm with
           distributionally robust optimization

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      Authors: Zeyu Zhou, Yuhui Wang, Mou Chen, Qingxian Wu
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Aiming at enhancing the extent of military automatization and the effectiveness of armed helicopters in complex battlefield environment, integrated fire/flight control (IFFC) coupler connects the fire control system and the flight control system which is used to generate the optimal flight command signals. However, it is difficult to obtain satisfactory flight command signals within a certain firing accuracy due to the unavoidable uncertain information in battlefield environment. In this paper, a new IFFC scheme is proposed for armed helicopters against complex combat by using the idea of distributionally robust optimization combined with the framework of trust region. Initially, a vector equation and coordinate transformation are employed to acquire the relative motion model of the IFFC coupler problem in complex battlefield environment. Moreover, an improved performance index is designed according to the constraints, and the original non-convex problem is handled by the Taylor formula combined with an improved BFGS (Broyden–Fletcher–Goldfard–Shanno) algorithm. Considering the uncertain parameters during optimization, the non-linear distributionally robust optimization is transformed into a linear matrix inequality optimization problem based on the worst-case conditional value-at-risk (WC-CVaR) approximation. Then, an algorithmic framework with a non-monotone adaptive trust region algorithm is given to obtain the optimal flight command signals. Finally, a simulation example is given to illustrate the effectiveness of the proposed approach.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-07-25T12:12:54Z
      DOI: 10.1177/09544100231189991
       
  • Design and dynamics of a 2PSS+PSR+SP+RUPUR-type parallel rotor of
           helicopter

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      Authors: Yi Lu, Zefeng Chang, Nijia Ye
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      A novel parallel rotor of the helicopter is designed by combining a 2PSS+PSR+SP+RUPUR-type parallel manipulator with a rotor of the helicopter. Its kinematics and dynamics models are established. Firstly, the structure principle and the merit performances of the parallel rotor are explained by comparing with conventional and existing rotors of the helicopter, and the degree of freedom of the parallel manipulator is calculated. Secondly, the kinematics formulas are derived for solving the displacement, Jacobian matrix, general velocity, Hessian matrix, and acceleration of the parallel rotor and the kinematic limbs. Thirdly, a dynamics model of the parallel rotor is established based on the derived kinematics formulas. Finally, the theoretical kinematics and dynamics solutions are verified by a simulation mechanism of the parallel rotor of the helicopter.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-07-21T11:11:15Z
      DOI: 10.1177/09544100231184644
       
  • Finite element analysis of the underslung carrier rocket effect on stress
           and strain distribution in a structure of the MiG-29 aircraft

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      Authors: Aleksander Olejnik, Stanisław Kachel, Piotr Zalewski, Robert Rogólski, Michał Jędrak, Michał Szcześniak
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The paper presents selected aspect of the analytical-conceptual research project entitled: Airborne-Rocket Launch System for Delivering Satellite Payloads into Low Earth Orbit – Feasibility Study. The aim of the project is to conduct series of aerodynamic, strength, and aeroelastic simulations of Polish aging combat aircraft (Mig-29 and Su-22) to explore applicability of both fighters as an airborne platform for carrying out carrier rockets with a detachable satellite payload. This work presents exemplary analyses in the area of airframe loads and structural strength and deformability of MiG-29 for predicted operational variants with carrier rockets put to the hardpoints under fuselage. The numerical simulations were conducted for a structural discrete model of the aircraft prepared for finite element analysis in MSC Software. Model development involved such aspects as precise discretization of geometric model, declaration of material constants, identification of structural properties, introduction of suitable merging connections for included airframe assemblies, and final validation of model mass and stiffness. The model was analyzed in MSC Nastran software with application of linear “Statics” solution. External flight loads introduced into the model were calculated for specific points of the flight envelope—the highest values of load factor were taken into consideration (n=9). The counterpart aerodynamic force distribution in a form of a set of equivalent lumped forces was calculated. Then, the aerodynamic and weight loads were added to the model as a set of forces applied to specific structural nodes. Additionally, weights of applicable carrier rockets were taken into account as concentrated forces applied to under-fuselage suspension hardpoints. Calculations were performed for several rockets of mass values between 250 and 1200 kg. Parametric dependencies were investigated as an effect of missile mass and size on stress and strain distribution over the whole structure. The areas of stress cumulations were identified. On the basis of static structural deformation, maximum wing tip displacements were assessed.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-07-21T02:16:59Z
      DOI: 10.1177/09544100231189942
       
  • Energy- and time-optimal reconfiguration of spacecraft clusters with
           collision avoidance

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      Authors: Yong Huang, Silang Sun, Jing Chu
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Spacecraft cluster reconfiguration is one of the enabling technologies to ensure non-traditional attributes of distributed space systems. This work treats energy- and time-optimal reconfiguration problems for both circular and eccentric reference orbits. Furthermore, typical local and coupling constraints have been taken into account. Particularly, focus is given to two coupling constraints: final configuration constraints and collision avoidance constraints. For final configuration constraints, a parameterization method is applied to ensure that the reconfiguration problem can be solved as only one optimization problem, rather than a large number of optimization problems resulting from the traditional discretization method. A generalized formulation is proposed for non-convex collision avoidance constraints, which are then convexified via linearization and convex restriction technology. This method provides the affine approximation as a special case. After incorporating above constraints, the reconfiguration problem is formulated as an open-loop optimal control problem, which is solved via the Gauss pseudospectral method (GPM). By virtue of elegant features of GPM, those solutions can serve as a counterpart and stepping stone for a distributed implementation of reconfiguration algorithms. Various simulations demonstrate that minimum-energy/time cluster reconfiguration problems with collision avoidance for circular and eccentric reference orbits can be solved effectively and efficiently using GPM.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-06-20T02:26:36Z
      DOI: 10.1177/09544100231179829
       
  • A new source finding and tracking analysis approach for the active
           reflector of five-hundred-meter aperture spherical telescope

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      Authors: Deshen Chen, Yan Zhang, Hongliang Qian, Kai Zhang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The FAST (Five-hundred-meter Aperture Spherical Telescope) is the world’s largest single-aperture radio telescope. During operation, FAST needs to follow the observed celestial body to adjust displacements, which can be divided into two processes: the source finding and tracking. In this paper, a new numerical method based on Vector Form Intrinsic Finite Element (VFIFE) is proposed to simulate the source finding and tracking process for FAST’s active reflector. The basic principle of static equilibrium and calculation flow of the sourcing and tracking analysis is proposed, and the finite element program is compiled to analyze the displacement process of the reflector cable-net structure. Then, six typical test conditions are selected to simulate the sourcing and tracking displacement process. The obtained final form in the equilibrium state adheres to the target configuration, demonstrating the applicability of the suggested approach and the correctness of calculation findings. In addition, the change in the actuator length and the structural force distribution can be simultaneously derived. These values serve as a vital theoretical foundation for FAST’s practical operation and regulation.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-06-19T03:59:50Z
      DOI: 10.1177/09544100231184647
       
  • Dynamics simulation of folding wing UAVs launched from a high-altitude
           balloon platform

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      Authors: Hangyue Zhang, Yanchu Yang, Rong Cai
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      It is a new application of the high-altitude balloon system to launch multiple small folding wing unmanned aerial vehicles (UAVs). Based on the design of the launching system, we conduct numerical simulations of the ejection process from the balloon platform and the subsequent UAV wing deployment with trajectory leveling operation. We use the Kane method to establish the dynamic model of the balloon launching platform in the inertial coordinate system (ICS). By introducing the degree of freedom of UAV sliding along the sliding track, we realize the dynamic simulation of eight UAV launching processes and obtain the instantaneous separated states. The folding wing UAV first deploys its wings after ejection, which has the coupling characteristics between structural deformation and attitude adjustment. It is regarded as a multi-rigid body connecting structure composed of the fuselage and four wings. We establish the dynamic simulation model by the Kane method in the UAV body coordinate system (BCS). The Radau pseudo-spectral method is used to calculate the flight trajectory of each UAV. This paper is an engineering application research and can provide a simulation reference for the launching test of the balloon-borne folding wing UAV program.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-06-15T08:50:03Z
      DOI: 10.1177/09544100231181218
       
  • Efficient on board storage and retrieval of fast maneuver profiles for
           space applications

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      Authors: Mark Karpenko, Roberto Cristi, Joshua Levitas
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Attitude guidance is a concept for implementing performance enhancing rotational maneuvers that uses a conventional closed-loop attitude control system to track an optimized maneuver trajectory. Minimum-time attitude guidance is presently being used for executing fast occultation avoidance maneuvers on NASA’s Lunar Reconnaissance Orbiter (LRO). A challenge in operationalizing the idea is related to the limited size of the spacecraft’s command buffer, which was not designed with maneuver tracking in mind. In this paper, we propose an interpolating pre-filter built on B-splines that can be used on board to process downsampled maneuver commands (to save buffer space) and provide attitude control inputs at the servo-rate. The approach is validated using a high-fidelity simulation of the LRO developed at NASA’s Goddard Space Flight Center.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-06-12T11:45:14Z
      DOI: 10.1177/09544100231181870
       
  • Topological optimization method of locking unit layout for space
           manipulator based on plant root adaptive growth theory

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      Authors: Wang Gang, Yao Yimeng, Wang Jingtian, Zhao Yue, Wu Xinyuan, Mei Tianyu, Huo Weiye, Kang Huifeng
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The method of locking point layout optimization and stiffness configuration for multi-joint complex mechanisms of space manipulator is proposed based on the root adaptive growth theory. A simplified model of the space manipulator and 3D spring support model is established. According to the proposed layout optimization and stiffness configuration method, the parallel optimization method and finite element simulation software are utilized to simulate and analyze the differentiation process of space manipulator locking units and the manipulator systems with different stiffness configurations. The results of the layout optimization and stiffness configuration method are compared with the results of the conventional method. It is verified that the fundamental frequency of the optimization and configuration results is higher than that of the conventional method, and the effectiveness of the optimization and configuration method is verified.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-06-10T07:57:13Z
      DOI: 10.1177/09544100231181480
       
  • Modelling of fire-suppressant injection into engine nacelle for various
           flight regimes

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      Authors: Mohamed A Mohamed, Tze H New, Bing F Ng
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      In this study, the injection of Halon 1301, an effective fire-suppressing agent, into a helicopter engine nacelle is modelled to provide insights into dispersion behaviour alongside complex flow physics. The injection velocity as well as the mass flow rate were retrieved via a 1-D pipe model to simulate nitrogen-pressurized flow of Halon 1301 in a four-branch pipe system. The Discrete Phase Model in ANSYS Fluent was then used to model the injection of Halon 1301 into an engine nacelle. To simulate engine operation conditions in forward flight and hover regime, external boundary conditions were prescribed to the pressure inlets in the nacelle. When Halon 1301 is injected into the engine bay via the first pair of injection points, the droplets immediately reach their boiling point of 215 K. This resulted in an explosive-dispersion behaviour with a cone angle in the range of 80°–90°. As the agent evaporates, the engine cools and another pair of injection points located at the rear of the engine is subsequently activated, helping to cool the engine further. The two flight regimes considered, namely, hover and forward flight, showed contrast in flow dynamics which affected the cooling of the engine as well as the spray dynamics. In particular, the forward flight case showed more recirculation zones compared to the hover case. The volume concentrations of Halon 1301 were plotted for 11 probe points within the nacelle, and it was observed that two locations showed traces of low concentration levels.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-06-10T06:29:01Z
      DOI: 10.1177/09544100231181866
       
  • Adjoint optimization of a multi-row transonic compressor based on an
           extended free-form method

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      Authors: Xin Li, Tongtong Meng, Weiwei Li, Ling Zhou, Lucheng Ji
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The adjoint method plays an important role in the aerodynamic design of turbomachinery. However, most optimization objects are only local parts of the fluid domain in turbomachinery, such as blade or end-wall. In this study, a novel parameterization method is adopted in the adjoint optimization framework to merge all design spaces together and then a typical multi-row compressor, Stage 35, is optimized by the in-house adjoint optimizer, TurboSim_un. The adiabatic efficiency of STAGE 35 is improved by 1.7%. Results show that the intersection of shock wave and boundary layer is weakened and the performance in mainstream is significantly improved.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-06-10T05:07:35Z
      DOI: 10.1177/09544100231182265
       
  • Design optimization of composite fan blade in aircraft engine subjected to
           bird strike loading

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      Authors: Gruhalakshmi Yella, Prakash Jadhav
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Bird strike has been a perennial problem for all airline companies in the world. It is the most important design criteria for the fan blades of an aircraft engine. As it is not possible to manufacture and test aircraft engines again and again for small design changes, through the simulation analysis, it is possible to study the ways to reduce the impact of the bird on a jet engine by using appropriate design and manufacturing methods for the blade. This research suggests using two fibers (hybrid) in place of the single fiber composite blade which is currently in use to reduce the delamination issues. In the first stage of this research, representative composite coupon models for combinations of hybrid fiber joint positions were created and linear static analysis was performed. For the validation of simulation methodology, a few coupons were manufactured and tested in the laboratory. Further, dynamic bird strike analysis on sub-element level models was carried out in the second stage with various joint location combinations. Next, the plate-level representative blade model was designed with the original dimensions of the aircraft engine fan blade, and bird strike analysis was performed. The behavior of the representative plate with hybrid interface was studied, and the levels of inter-laminar shear strain were checked, by varying the joint location of the two composites. Some of the shortlisted cases do show significant promise of being damage tolerant under bird strike loading.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-06-07T06:05:45Z
      DOI: 10.1177/09544100231181054
       
  • Study of fluid-dynamic behavior in a convergent–divergent nozzle by
           shape optimization using evolutionary strategies algorithms

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      Authors: Jhan Bahamon, Manuel Martinez
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The performance and thrust of a rocket propulsion system are based mainly on the utilization of the enthalpy of the propellants in the combustion chamber. This accumulated energy is transformed into kinetic energy by the expansion and acceleration of the gases produced by the chemical reaction of combustion, using a device known as a nozzle. This project studies the aerodynamic profile to trace the wall contour of a C-D nozzle based on the technical operating conditions of a rocket engine. The wall contour is traced using different design methods and, for each nozzle section, the behavior of the fluid-thermal properties of the flow field along the flow trajectory of the aerospace nozzle is analyzed. This is necessary because, in each wall contour suggested by the models, the angle of inclination of the curvature is different (the concavity or shape of the curve changes) and, therefore, the physical magnitudes of the properties vary according to the contour. To determine which design complies with the concept that processes occurring within a nozzle are isentropic and reversible, a statistical analysis of data dispersion is performed to choose the design with the lowest energy losses as a function of friction and entropy. An unconstrained optimization is applied to maximize or minimize the cross-sectional area of the nozzle geometric profile through genetic algorithms. To corroborate the nozzle wall contour and the design methodology used, a simulation is performed to evaluate the similarities between the operating characteristics and Mach number with another nozzle of a J-2 rocket engine.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-06-07T05:58:16Z
      DOI: 10.1177/09544100231163372
       
  • Coating roughness impact on the combustion chambers life of the turbo
           engines

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      Authors: Mana Masrouri, Amir Mahdi Tahsini, Seyed Erfan Vahabi
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The objective of this study is to determine the impact of the convective heat transfer coefficient and the heat conduction coefficient on the metal temperature by studying heat conduction in the base metal and the coating under hot gas convection as well as the cooling flow using analytical methods. Increasing the convective heat transfer results in lower conduction of the coating that is necessary to maintain the metal temperature at the determined level. The surface roughness of the coating is therefore an influential factor in determining metal temperatures and plays a significant role in the lifespan of the hot sections of turbo engines. This phenomenon is numerically studied for the SGT-100 combustion chamber and the results demonstrate that the roughness can considerably increase the wall heat flux of the combustor. This means that the coating should be manufactured so that the coating surface has a lower roughness level. Otherwise, the higher heat flux will cause damage to the combustion chamber.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-06-05T03:29:07Z
      DOI: 10.1177/09544100231181209
       
  • Efficient large multibody flight dynamic simulation through improved
           nonlinear control constraint stabilization

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      Authors: Jake Wachlin, Cason Butler, Mark Costello
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Some air vehicles are configured such that major components exhibit relative motion with respect to one another where this relative motion significantly affects vehicle motion. In these cases, multibody flight dynamics is needed to adequately model system dynamics. This paper reports on a numerically efficient and versatile method for multibody flight dynamic simulation where the air vehicle is idealized as a collection of rigid bodies connected together by a set of joints. The method uses constrained coordinates with a constraint stabilization method based on a nonlinear control framework. The key innovation lies in relating the connections of the rigid bodies to an undirected graph and its adjacency matrix. By reordering connections, the bandwidth of the adjacency matrix can be minimized leading to substantial computational improvements. These improvements are applied to several air vehicle systems to highlight the computational benefits of the proposed technique.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-06-02T11:32:16Z
      DOI: 10.1177/09544100231179855
       
  • Acoustic velocity analogy formulation for sources in quiescent medium

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      Authors: Jiahua He, Sidan Xue, Qiuhong Liu, Dangguo Yang, Liangquan Wang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The prediction of near field acoustic velocity is necessary when using equivalent source method and evaluating multi acoustic fields problem. According to the idea of acoustic analogy, this paper induces a vector wave equation of aeroacoustics by rearranging the conservation equations of mass and momentum with a permeable surface. Then, an analytical formulation of the acoustic velocity, called formulation V2A, is derived for sources in a quiescent medium by solving the vector wave equation with the free-space Green’s function. The validity of the formulation is confirmed by numerical results for a stationary monopole, a stationary dipole source, and a rotating monopole source in a quiescent medium. The result indicates that the predication of formulation V2A is nearly identical to the exact solutions no matter in far-field or near-field.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-05-12T06:37:11Z
      DOI: 10.1177/09544100231174332
       
  • In-motion initial alignment method using Cayley–Kalman filter on
           special orthogonal group

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      Authors: Fujun Pei, Hengming Zhang, Siyuan Li
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Aiming at the in-motion initial alignment problem of strapdown inertial navigation system (SINS), this paper proposed a precise direct in-motion alignment method based on attitude matrix representation and Cayley–Kalman filter on the special orthogonal group. There are two innovations in this paper. First, as an element of the special orthogonal group [math], the error attitude matrix is used to construct an in-motion alignment model, and it is transformed into the vector space to represent the attitude error state. The error matrix was used as a state to decrease the influence of the state-dependent problem. Second, this method uses the Cayley transform to replace the Taylor expansion to derive the update equation, which is a no approximation mapping relation to assure accuracy when deriving the filtering algorithm. Simulation and experimental results demonstrate the proposed alignment method has advantages over the existing methods in alignment accuracy and alignment time and performs well in the in-motion alignment process of SINS.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-04-20T12:31:21Z
      DOI: 10.1177/09544100231169878
       
  • Adaptive diagnosis and non-fragile predictive control for HFV engine with
           non-Gaussian uncertain output

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      Authors: Kai-Yu Hu, Zian Cheng, Jingxiu Gong
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      This study presents an adaptive fault estimation and model predictive fault-tolerant control (FTC) for the hypersonic vehicle engine with non-Gaussian uncertain output jet plume. The non-Gaussian probability density function (PDF) describing the plume velocity in a stochastic system is approximated by Type II fuzzy radial basis functions. In the fault observer, the novel prey adaptive estimation method is designed for the valve faults with different amplitudes. Ultimately, this fuzzy-prey fusion adaptive observer shields perturbation and accurately estimates complex faults including incipient and intermittent faults. A predictive tolerant controller compensates for all the faults effects and non-fragile compensation factors of FTC eliminate the perturbation interference, thence the output PDF matches with the expected value. Finally, the more refined internal structure of plume output distribution replaces the local and rough valve position variables, helping this study realizes the hypersonic vehicle engine integrated refine control. Simulation result verifies the effectiveness of the proposed approaches and the superiority compared with the existing method.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-04-18T04:02:41Z
      DOI: 10.1177/09544100231158271
       
  • Optimization of novel flat serial single-phase radiators for spacecraft
           thermal control

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      Authors: Phanidra B. Chiranjeevi, Venkateswaran Ashok, K. Srinivasan, T. Sundararajan
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Space thermal radiators play a significant role in the thermal management of spacecraft. With the increase in heat dissipation requirement, the heat pipe radiators are being replaced by mechanically pumped fluid loop radiators. In recent years, authors proved that optimum serpentine serial radiators are advantageous over conventional optimum parallel radiators in terms of the mass and pressure drop. The spiral radiators, inspired by spiral plate heat exchangers, are proposed and analyzed as a replacement for the serpentine serial radiators. Performance analysis of radiators is carried out using conjugate heat transfer analysis. Conjugate heat transfer results are validated with the experimental results obtained from the literature. The performance analysis indicated that the circular spiral radiator performs better than the other two types due to their lower mass and pressure drop. Optimization of radiators is carried out using Taguchi Signal to Noise ratio analysis. Analysis of Variance is conducted to determine the percentage contribution of each variable to the performance of the radiator. When lower pressure drop requirement is prominent, the contribution of the diameter of the tube is 79.3%, whereas the contribution of fin thickness and pitch of the tubes are only 6.1% and 8.2%, respectively. The contribution of the fin thickness is 57.39%, the diameter of the tube is 37.71%, and the pitch of the tubes is 1.89% when the lower mass of the radiator is the prime requirement. The high-performance spiral radiators may find their application in the thermal management of human space flights and high-power GEO satellites.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-04-17T07:21:22Z
      DOI: 10.1177/09544100231170416
       
  • A review on insects flight aerodynamics, noise sources, and flow control
           mechanisms

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      Authors: Foad Moslem, Zahra Babaie, Mehran Masdari, Kirchu Fedir
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Wildlife always acts as an inspiration source for humans to help them study and mimic flight methods. Insects are one of the most important sources of biological systems’ inspiration to control flow and reduce aerodynamic noise. Insects are classified into different kinds, and most can fly by fluttering their wings. In general, insects’ flight muscles are divided into direct and indirect types that act synchronously and asynchronously with nerve impulses, respectively. These muscles help insects use a mixture of rotating, flapping, and pitching movements to achieve specific wing kinematics. Insects use various mechanisms for generating aerodynamic forces, including the Weis-Fogh or clap and fling mechanism, delayed stall due to unsteady motion (Wagner effect), wing rotation (Kramer effect), wake capture or wing–wake interaction, added mass, and absence of stall. On the other hand, the insect noises are divided into aerodynamic and structural. Insects’ aerodynamic noise is created by fluctuating forces, flow–solid interaction, shed vortex, and turbulence inflow. Meanwhile, insects’ structural noise is made by frictional and tymbal mechanisms. Their flow control methods are classified into two categories: wing shape and sub-structures. Wing shape features such as planform, chord length and location, twist, sweep, wingtip, and aspect ratio influence the flow around the insects. The sub-structures such as leading edge, trailing edge, swallowtail, and surface textures affect the flow too. A thorough understanding of insects’ fly, aerodynamic noise, and their control flow techniques will significantly help engineers to produce competitive products with better aerodynamic performance and aeroacoustic signature.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-04-14T07:44:26Z
      DOI: 10.1177/09544100231169345
       
  • High-altitude airship variable-pitch propeller performance analysis at
           multiple altitudes

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      Authors: Wang Dongchen, Song Bifeng, Jiao Jun, Xue Dong
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      To achieve better propulsion performance for high-altitude airships, this paper proposes a variable-pitch propeller design and performance analysis. Propeller surrogate models were constructed based on an in-house fluid–structure solver and validated by a wind tunnel experiment. Based on the surrogate model, this paper studied propeller performance under the common influence of propeller pitch variation and rotational speed, and proved the positive effect of the variable-pitch propeller on maintaining relatively high efficiency in large rotational speed range. This paper compared the performance of variable-pitch propellers and fixed-pitch propellers under the constraints of the motor. The results show that introducing variable-pitch propellers to high-altitude airships can significantly improve propeller performance at multiple altitudes and laminar wind speeds. And the potential of airship weight reduction brought by the variable-pitch technique is discussed as well.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-04-13T05:11:09Z
      DOI: 10.1177/09544100231167710
       
  • Variable-horizon predictive tracking control for air-breathing hypersonic
           vehicle based on composite disturbance observer

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      Authors: Jin Zhao, Mou Chen
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      In this paper, a variable-horizon predictive tracking control (VHPTC) scheme based on composite disturbance observer (CDO) is proposed to investigate the attitude tracking problem for an air-breathing hypersonic vehicle (AHV) subject to external matched and mismatched disturbances. An explicit predictive tracking control term with the variable horizon is employed to reduce the online computation and improve the control performance of the AHV system. To comprehensively suppress the negative influences caused by the matched and mismatched disturbances, a CDO is constructed to estimate the unknown disturbances. Moreover, to further guarantee the stability of the closed-loop system affected by the resulting disturbance estimation error, the auxiliary control term is presented. Combining the predictive tracking control term with the variable horizon, the auxiliary control term, and the disturbance compensation control term obtained by CDO, the entire VHPTC law for the AHV system is obtained. Through the Lyapunov analysis, the rigorously exponential stability of the closed-loop system is ensured by the proposed CDO-based VHPTC scheme. The simulation results demonstrate the effectiveness of the presented strategy for the AHV attitude system.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-04-10T01:37:01Z
      DOI: 10.1177/09544100231162734
       
  • Research on selection method of aero-engine health parameters based on
           correlation and condition number

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      Authors: Cheng Chen, Qiangang Zheng, Haibo Zhang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Aiming at the problem of how to select aero-engine health parameters when the number of sensors is limited, a method of selecting aero-engine health parameters based on correlation and condition number is proposed. Firstly, the engine health parameters are preliminarily selected based on correlation. When the influence of two health parameters on engine output parameters is strongly correlated, only one of them needs to be selected. Then health parameters are further selected based on condition number of sensors parameters degradation matrixes. The larger the condition number is, the more ill conditioned the matrix is and the worse the estimation effect of the on-board model is. According to this, the combination of health parameters with the minimum condition number is selected. The proposed method can quickly select optimal health parameters and improve the accuracy of engine adaptive estimation. The results demonstrate that the stronger the correlation between the two health parameters, the greater the impact on the accuracy of the on-board model. Compared with the singular value decomposition-Kalman filter (SVD-KF) method and other combinations of health parameters, the on-board model accuracy of the optimal combination selected by this method is greatly improved, and has the best state parameter tracking effect.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-04-08T06:37:25Z
      DOI: 10.1177/09544100231166963
       
  • Adaptive second order sliding mode guidance law for missile-target
           interception with fuzzy logic system

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      Authors: Handan Gürsoy-Demir, Mehmet Önder Efe
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      This paper presents the design of a 3D missile guidance law based on a second order sliding mode control technique employing an adaptive tuning law and a fuzzy gain scheduling. At the outset, the super-twisting sliding mode guidance law is obtained to overcome the chattering phenomenon. Then, without the knowledge about the bounds of disturbances, an adaptive law is used to determine the control gains. The results are enhanced using a fuzzy module that provides the controller parameters according to a set of linguistic rules. Finally, a comparative set of simulation results are given. To verify the performance and effectiveness of the proposed guidance law, we compare the performances of the traditional sliding mode (SM) guidance law, the traditional super-twisting sliding mode (STWSM) guidance law, the adaptive super-twisting sliding mode (ASTWSM) guidance law and the adaptive fuzzy super-twisting, sliding mode (AFSTWSM) guidance law. The simulation scenarios consider fundamental target movements. The results demonstrate that the proposed adaptive guidance laws display better performance in terms of miss distance, intercept time, and final closing velocity compared the alternatives considered in this study.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-04-08T06:33:25Z
      DOI: 10.1177/09544100231156638
       
  • The cubic pitching moment coefficient of spin-stabilized projectiles

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      Authors: Sijiang Chang, Jingwen Zhang, Wei Wei
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      This technical note presents a feasible method to effectively predict the cubic pitching moment coefficient for spin-stabilized projectiles. First, a surrogate model for predicting the cubic moment coefficient is constructed by using the Kriging method to relevant published data of several typical spin-stabilized projectiles. The result of a wind tunnel test validates the accuracy of the Kriging prediction, implying that this prediction model complements the current research literature. Second, the global sensitivity analysis combined with this prediction model is used to assess the effect of the shape parameters of spin-stabilized projectiles on the cubic pitching moment coefficient. As a result, the relationship between the shape parameters and the nonlinear pitching moment coefficient is preliminarily explored. The results of an example show that the cylindrical part length, the head shape parameter and the nose length have greater influence, whereas the boat-tail length has the weakest influence.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-04-06T07:20:09Z
      DOI: 10.1177/09544100231167719
       
  • Dynamics-based deep learning and fractional-order fixed-time sliding mode
           control for space robot impedance system

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      Authors: Tongyu Zhao, Guanghui Sun, Weihong Zhu
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      To complete complex tasks with space robots in the impedance environment, sliding mode control (SMC) has been proposed and plays an important role in the past decades. Learning-based control has also met with great success in robotics and has been closely followed in the control of space robots. However, as an interdisciplinary, only a few studies have combined deep learning and traditional controller in the space robot directly. This paper proposes a novel fractional-order fixed-time SMC for impedance control of space robots, taking advantage of a model-based deep learning approach to obtain the dynamics of space robots. The learning results are used to make predictions for the data-based robot dynamics. The fractional-order fixed-time SMC controller is added to that data-based model, and it ensures the finite closed-loop convergence time. Small-dataset training is more reasonable in the situation of space robots, which reduces training time and sampling size. Compared to traditional methods, combining deep learning and fractional-order fixed-time SMC provides better tracking performance and improves closed-loop robustness. It accomplishes the control target in the impedance model using the estimated data-driven parameters. Theoretical analysis proves the closed-loop behavior, and simulation results verify its effectiveness.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-04-06T01:15:25Z
      DOI: 10.1177/09544100231157954
       
  • Contact stress analysis of external non-variable multi-modulus spur gear
           pairs

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      Authors: Zengbao Zhu, Hongbo Cui, Mingzhen Gong, Heyun Bao, Rupeng Zhu
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The conditions of correct gear engagement of a pair of involute gears and the principle of geometric relationship of involute tooth profile are derived to determine the pitch point of externally meshing non-variable multi-modulus spur gear pairs into the double tooth engagement region. The Hertzian contact stress model is used as the basis to derive the contact stress calculation equations for pitch point and other characteristic contact points, and the variation of the contact stress distribution on the contact line with the module ratio is analyzed. The results demonstrate that when the number of teeth of the gear pairs is determined, the larger the value of the module difference, the easier it is for the pitch point of the gear pairs to be in the double tooth meshing zone. Except for the double tooth meshing out point, the contact stress decreases with the increase of module ratio, and the maximum point of contact stress is at the upper boundary point of the single tooth meshing zone.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-04-05T11:06:15Z
      DOI: 10.1177/09544100231167904
       
  • An innovative integrated path planning and trajectory tracking framework
           for a quadrotor slung load system in an urban environment

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      Authors: Peyman Abeshtan, Fariborz Saghafi
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      In this paper, a hybrid path planning and trajectory tracking controller for a quadrotor slung load system is presented. This controller has benefited from the fuzzy inference system in its tracking and swing stabilization tasks. This system also plays an important role in creating a grid-based obstacle avoidance method that works based on the concept of generating Non-stationary Artificial Potential Field (NAPF) in the proximity of the objects tracking a virtual target on the path computed by A* algorithm. The weakness of the conventional artificial potential field method, that is to stuck in local minima, is now resolved by this so-called hybrid A*-NAPF method in which the potential field is non-stationary. The A* algorithm as a fast optimal path determination method computes the discrete initial path using a network of grids already generated through transferring the environment to a binary occupancy map. The performance of the whole integrated system is investigated through various simulation scenarios including those with moving obstacles. The results indicate a very good performance with high adaptability characteristic.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-03-31T12:53:13Z
      DOI: 10.1177/09544100231166033
       
  • Nonlinear aeroelastic stability analysis of a folding wing by using
           geometrically exact fully intrinsic beam equations

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      Authors: Sayed Hossein Moravej Barzani, Hossein Shahverdi
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      In this paper, the aeroelastic instability of folding wings by using the geometrically exact fully intrinsic beam equations is investigated. The important advantages of these equations in comparison with other structural beam equations are complete modeling without simplifying assumptions in large deformations, low-order nonlinearities, and thus less complexity. For the first time, folding angles have been implemented in the geometrically exact fully intrinsic beam equations and hence this is the main novelty of this study. The applied aerodynamic loads in an incompressible flow regime are determined using Peter’s unsteady aerodynamic model. In order to check the stability of the system, first the resulting non-linear partial differential equations are discretized by employing the central finite difference method, and then linearized about the nonlinear steady-state condition. By obtaining the eigenvalues of the linearized system, the stability of the wing is evaluated. Furthermore, investigation of the effects of some important parameters such as stiffness ratio and length ratio on the flutter speed of the folding wing for various folding angles, is another achievement of this study. It is observed that the geometrically exact fully intrinsic beam equations can model the folding angles for the aeroelastic analysis more accurately and the capabilities of these equations became more specific.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-03-31T11:00:59Z
      DOI: 10.1177/09544100231167728
       
  • A modified dual time integration technique for aerodynamic quasi-static
           and dynamic stall hysteresis

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      Authors: Mohamed Sereez, Nikolay Abramov, Mikhail Goman
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Simulation of the aerodynamic stall phenomenon in both quasi-static and dynamic conditions requires expensive computational resources. The computations become even more costly for static stall hysteresis using an unsteady solver with very slow variation of angle of attack at low reduced frequencies. In an explicit time-marching solver that satisfies the low Courant number condition, that is, [math], the computational cost for such simulations becomes prohibitive, especially at higher Reynolds numbers due to the presence of thin-stretched cells with large aspect ratio in the boundary layer. In this paper, a segregated solver method such as the Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) is modified as a dual pseudo-time marching method so that the unsteady problem at each time step is reformulated as a steady state problem. The resulting system of equations in the discretized finite volume formulation is then reduced to zero or near-zero residuals using available convergence acceleration methods such as local time stepping, multi-grid acceleration and residual smoothing. The performance and accuracy of the implemented algorithm was tested for three different airfoils at low to moderate Reynolds numbers in both incompressible and compressible flow conditions covering both attached and separated flow regimes. The results obtained are in close agreement with the published experimental and computational results for both quasi-static and dynamic stall and have demonstrated significant savings in computational time.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-03-29T08:40:07Z
      DOI: 10.1177/09544100231164192
       
  • Numerical solution of spacecraft pursuit-Evasion-Capture game based on
           progressive shooting method

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      Authors: Tian Liao, Shunli Li, Xinlong Chen, Mengping Zhu
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The time optimal pursuit-evasion-capture (PEC) game problem for two spacecraft with continuous constant thrust is studied, which is a typical and considerable game scenario in practice. Progressive Shooting Method (PSM) is proposed to solve the PEC game in this paper. The method solves the problem in two stages. First-shooting settles a simplified problem by substituting CW dynamics to simple dynamics, while second-shooting settles the original problem with the results of first-shooting. For first-shooting, an analytic initial guess construction method based on prior information is proposed, in which vague adjoint variables are expressed by quantities with clear physical meanings. Through qualitative analysis for the optimal trajectory, the quantities are approximately estimated and then analytic expressions of an initial guess are constructed. The proposed method provides an instructive way to deal with the difficulty that an initial guess is hard to provide for an optimal control problem based on indirect-method. Numerical results show that a PEC game can be solved by the proposed method with well convergence and high computational efficiency.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-03-24T03:23:48Z
      DOI: 10.1177/09544100231164269
       
  • Optimal hybrid Coulomb control for on-track rendezvous and docking of
           spacecraft

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      Authors: Gaurav Kumar, Dipak Kumar Giri, Shashi Ranjan Kumar
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      This paper investigates the dynamics of on-track rendezvous and docking of two spacecraft, and stabilization using hybrid Coulomb control. Modeling electrostatic forces and torques for control of complex spacecraft geometries like cylinders is challenging. Point mass assumption of the spacecraft that disregards the chaser dynamics will lead to errors in force estimation during the terminal docking phase, resulting in a mission failure. This paper uses the effective sphere method to model Coulomb interactions between the chaser and the target. The method is coupled with the chaser’s tumbling motion about its body axes to develop a relationship between electrostatic force and attitude. The relative attitude dynamics of the chaser is then derived and incorporated into the system dynamics. Differential gravity and hybrid thrusters are used to stabilize the relative attitude of the two bodies. The charge-voltage relations are used to compute potential variations for the Coulomb control. An optimal linear quadratic tracking control is proposed for tracking a reference trajectory generated using solutions of Clohessy-Wiltshire-Hill’s equations. Numerical simulations are carried out for both non-linear and linear models of the Coulomb spacecraft to validate the proposed concept. Results have also been compared with an existing voltage feedback controller to demonstrate the merits and challenges of electrostatic actuation for rendezvous and docking.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-03-22T05:32:23Z
      DOI: 10.1177/09544100231162662
       
  • Aerostructural performance improvement in an unmanned long endurance
           aircraft using adaptive wing concept

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      Authors: Ashok K Sampath, Madhusudan A Padmanabhan, Subhaschandra Kattimani
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      This paper presents an analytical research study to improve the aerostructural performance of an unmanned medium altitude long endurance aircraft using the adaptive wing concept. Aerodynamic drag and wing root loads are minimized by optimal scheduling of multiple trailing edge flaps located on the wing. A trim optimization process is developed specifically for this purpose. The aeroelastic model is based on finite element formulation for the structure and doublet lattice method for the aerodynamics. A nonlinear numerical lifting line method is used, in combination with airfoil wind tunnel data, to estimate the induced and total drags. Results are presented for the current aircraft configuration and a more flexible proposed configuration, thereby providing an uncommon perspective on the effect of flexibility on the adaptive wing. For example, the benefits of optimal flap deployment turn out to be greater for the flexible aircraft than for the rigid one. It is hoped that this work and its insights will also aid the multidisciplinary design optimization of future aircraft.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-03-14T09:34:24Z
      DOI: 10.1177/09544100231163904
       
  • Implementation of a finite element modelling strategy for the prediction
           of aircraft tyre response

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      Authors: Amit Ramji, Marzio Grasso, James Chase, Hasher Maqbool, Michal Krypciak, Veronica Merchante, James Brighton
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      This paper presents the finite element modelling (FEM) strategy to identify the structural response of aircraft tyres under quasi-static and taxiing load conditions. The tyre FEM was developed to simulate the aircraft tyre/ground interaction for a range of inflation pressures under vertical, lateral, longitudinal, torsional, yawed and un-yawed rolling. A thorough comparison for validation purposes is made between the test and simulation data extracted from the FEM. The reinforcement plies of the tyres are modelled in a computationally efficient manner whilst also considering the variable fibre volume fractions and ply discontinuities within the tyre. The accurate material characterisation at coupon level combined with the overall modelling approach allowed most simulated responses to match the experimental stiffness within 12% against best fit curves of similar tyre types and within 5% for the majority of test comparisons.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-03-11T09:00:33Z
      DOI: 10.1177/09544100231162659
       
  • Experimental and numerical research on flow characteristics of inlet
           particle separator for aero-engine under the influence of water film

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      Authors: Mingcong Luo, Qionglei Hu, Aocheng Liu, Kim Tiow Ooi, Qun Zheng, Shilin Yan
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      An aero-engine must be able to operate in all-weather conditions, which requires the aircraft to be safe throughout the flight even in bad weather. Excessive intake of rainwater can induce stall and surge of compressor and flameout of combustion chamber, which will lead to the loss of power of the engine. In rainy weather, water come into the engine inlet protection device, which directly determines the compressor inlet conditions and will further affect the compressor working condition and the matching features. In this paper, special attention was paid to the experimental characteristics of aero turbo-shaft engine inlet particle separator (IPS) and the numerical study employing ANSYS-CFX under water spraying condition. Based on the phenomenon of water film forming on the wall surface of the IPS and the experimental data under different water spraying conditions, combined with the predictions from CFD study, an empirical model of water film flow on the wall surface has been developed. The results indicate that in the case of high water ingestion, droplets will inevitably form water film on the wall after entering the IPS. Due to the viscous resistance of wall water film and its influence on the airflow boundary layer, the flow state inside the IPS will change. By establishing a wet wall water film model, the flow characteristics near the wall are closer to the experimental state. The total pressure loss prediction error was reduced from 24.8% to 5.2% and 26.4% to 5.7% under the uniform water spraying rate of 2.93% and 4.84%, respectively.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-03-10T10:13:49Z
      DOI: 10.1177/09544100231162425
       
  • Research on afterburning control of more electric engine with a nonlinear
           fuel supply system

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      Authors: Zhihua Xi, Yong Wang, Haibo Zhang, Fengyong Sun, Qiangang Zheng, Zhemin Zhu
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      More electric engine (MEE) with electric pump metering fuel has the problem of unstable engine control due to the dead-zone characteristics of afterburner fuel actuator. On the basis of conventional μ modified adaptive control method, a compound modified adaptive control (CMAC) system based on neural network inverse model is proposed in this study. At first, the afterburner fuel actuator model of MEE is established through Simulink/AMESim co-simulation to study its fuel supply characteristics and reveal the reasons for dead-zone characteristics of the actuator. Subsequently, an integrated model of afterburner fuel actuator/MEE is established to investigate the effect of dead-zone characteristics on engine performance. Finally, the CMAC system for afterburner fuel flow closed-loop control based on neural network inverse model and improved μ modified adaptive control method is designed. The simulation results show that the dead-zone characteristics of afterburner fuel actuator can cause engine shaking and unstable operation. The engine thrust has a continuous fluctuation with amplitude of about 0.2%. The proposed CMAC system can effectively avoid the dead-zone interval of actuator and achieve stable transition of the engine state in the entire operating range of the afterburner fuel actuator. Thus, the stability of the control system can be significantly improved. Meanwhile, the improved μ modified adaptive control algorithm in the CMAC system has better dynamic characteristics when compared with the conventional μ modified adaptive control algorithm.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-03-09T12:26:22Z
      DOI: 10.1177/09544100231155696
       
  • Comparison between two computational fluid dynamics methods for gust
           response predictions

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      Authors: Zhenlong Wu, Yuan Gao, Xiaoming He, Weizhe Fu, Jianqiang Shi, Zhibo Zhang, Ruitao Zhou
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Based on the open-source computational fluid dynamics (CFD) platform, OpenFOAM, two numerical simulation methods for gusty inflow characterization and gust response prediction are implemented by solving the fundamental incompressible unsteady Reynolds averaged Navier–Stokes (URANS) equations. One is the Field Velocity Method (FVM) and the other is the Oscillating Vane Method (OVM). The gust velocity field is characterized and the aerodynamic responses of some airfoils under the Sears-type sinusoidal gusts are predicted by both gust simulation methods. The results indicate that both methods are capable of obtaining satisfactory gusty inflow conditions as expected as well as the airfoil aerodynamic responses. Comparatively, from the perspective of computing cost, the FVM is more advantageous in reducing the computational resources than the OVM while simultaneously ensuring the computational accuracy.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-03-09T10:12:23Z
      DOI: 10.1177/09544100231163202
       
  • A novel method to identify the multiple faults of intermediate bearing
           based on multiscale Lempel–Ziv complexity enhancement

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      Authors: Mingyue Yu, Guihong Guo, Haonan Cong, Minghe Fang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      In order to solve the difficulty to correctly identify a compound failure in intermediate bearing of aircraft engine, the paper has brought forward the method of strengthening fault feature information of intermediate bearing with weighted multiscale Lempel–Ziv complexity parameter. The method works by combining multiscale Lempel–Ziv complexity parameter (M-LZC) with wavelet transform (WT) and singular value decomposition (SVD) and implements the feature extraction and identification of compound failure in intermediate bearing. Firstly, failure information from different frequency bands of casing vibration signals is separated and signals are denoised based on WT and SVD difference spectrum. Secondly, concerning that the larger Lempel–Ziv complexity (LZC) of signal is, the more abundant failure information in signal will be; meanwhile, so as to avoid “excessive coarse graining” caused by traditional binarization method, M-LZC values of component signals after denoising are used to describe the failure feature information included in component signals. Thirdly, to further strengthen the failure feature information of intermediate bearing, larger weight value will be endowed to the component signals containing more abundant failure feature information. Failure information is boosted by M-LZC weight coefficient of component signal. Finally, component signals of an enhanced feature are reconstructed and the spectrum of reconstructed signal is used to make precise identification of compound failure type of intermediate bearing in aircraft engine.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-03-09T09:03:36Z
      DOI: 10.1177/09544100231153498
       
  • Real-time robust tracking control for a quadrotor using monocular vision

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      Authors: JR Montoya-Morales, ME Guerrero-Sánchez, G Valencia-Palomo, O Hernández-González, FR López-Estrada, JA Hoyo-Montaño
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      In this paper, the autonomous trajectory-tracking problem for an Unmanned Aerial Vehicle (UAV) based on Sliding Mode Control (SMC) algorithms is treated. The control system is implemented in real-time to stabilize a commercial AR.Drone 2.0 quadrotor using monocular vision. The under-actuated mathematical model is based on the Newton-Euler formulation. The algorithm allows the stabilization of the quadrotor in all its states under the simultaneous effect of parametric uncertainties and constant external disturbances. The vision algorithm uses a monocular camera to estimate the vehicle’s position. The experimental test results and numerical simulations show the effectiveness and robustness of the proposed controller.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-24T09:46:06Z
      DOI: 10.1177/09544100231158265
       
  • Design studies for a light aircraft wing with highly integrated
           load-bearing hydrogen tanks using multi-objective optimization methods

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      Authors: Felix Friedmann, Hannes Rienecker, Florian Dexl, Andreas Hauffe, Klaus Wolf
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      To enable emission-free flight, the use of hydrogen as an energy carrier in aircraft is one possible solution. However, hydrogen storage is a challenging task. The current paper presents a design study for a light aircraft wing with highly integrated load-bearing hydrogen tanks using an automated optimization method by means of Evolutionary Algorithms. With this method, both preliminary investigations and a more detailed design of structural wing concepts with highly integrated hydrogen vessels were carried out.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-24T07:54:31Z
      DOI: 10.1177/09544100231155697
       
  • Pipeline fault simulation and control of a liquid rocket engine

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      Authors: Yuqiang Cheng, Runsheng Hu, Jianjun Wu
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The feedback control system was designed to control the pipeline blockage and leakage fault. Based on the open-loop engine system, different degrees of faults were simulated, and the changes in system parameters when faults occur were analyzed. Then, the faults were injected into the engine system with feedback control, and the effects of the controller to different degrees of faults and the changes of the parameters of the electric pump with the controller were studied. The simulation results showed that under the action of the feedback control system, the deviation of the engine system parameters caused by these faults can recover to the set value within a few seconds. When the fault disappears, the system parameters can be still within the normal operating range.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-23T02:12:08Z
      DOI: 10.1177/09544100231157139
       
  • A fault diagnosis method based on improved parallel convolutional neural
           network for rolling bearing

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      Authors: Tao Xu, Huan Lv, Shoujin Lin, Haihui Tan, Qing Zhang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      There are many disadvantages for traditional Convolutional Neural Network (CNN) in rolling bearing fault diagnosis, such as low efficiency, weak noise immunity, and poor generalization with changing load. To solve the problem, this paper proposes a methodology of improved parallel CNN (IPCNN). In IPCNN, the simple pooling layer is removed and the parallel structure is to stack directly convolutional layers, with three branches, each branch has 4 layers, where the convolution kernels are all 3 × 3 and the stride sizes are 1, 2, and 3, respectively. The structure that is capable of feature fusion can extract features from the input information. Subsequently, the global average pooling (GAP) layer is used for down sampling, and the bearing faults are classified by the fully connected (FC) layer. In addition, the effectiveness of the proposed model structure is verified by testing the datasets. To further verify the validity of the model, the performance of the model was evaluated by diagnostic accuracy, prediction time, SD, and model size. In order to verify the noise immunity and generalization of the proposed model, the AlexNet, Vgg16, and ResNet18 models are compared, respectively. By performing 2D gray images transformation on the Case Western Reserve University (CWRU) bearing data, rolling bearing fault diagnosis method based on IPCNN model has higher efficiency, stronger noise resistance in the noise environment, and better generalization ability when the load changes.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-21T02:00:02Z
      DOI: 10.1177/09544100231158421
       
  • Advanced fault detection and diagnosis in spacecraft attitude control
           systems: Current state and challenges

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      Authors: Seid H Pourtakdoust, Mohamad Fakhari Mehrjardi, Mohammad Hossein Hajkarim, Forough Nasihati Gourabi
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      A review of advanced fault detection and diagnosis (FDD) techniques in attitude control systems (ACSs) of spacecraft is presented. In the first part of the paper, several types of ACS failure scenarios with their practical solutions are presented. Next, the existing approaches to FDD are considered and classified based on different criteria, including applications and design techniques. The literature of this part showed that to enhance ACS operational safety, predictability of failure of an ACS and/or of its components as well as reducing the possibility of failure occurrence is imperative. In addition, fast FDD of various kinds of failures is necessary to guarantee the required reliability of an ACS. The second part of this study highlights challenges involved with different FDD approaches, emphasizing their practical applicability. Current research gaps in FDD techniques such as insensitive residual signal, process monitoring methods, accurate plant model design, easy-to-use software development, FDD tuning process, dealing with noisy sensor measurements, time taken for fault management, the sensitivity of FDD system to faults, and FDD robustness are further elaborated on. Subsequently, the state-of-the-art FDD and its future needs are reflected on. The results of this study could direct spacecraft manufacturers and ACS providers to focus on future needs and improve ground testing for enhanced operational reliability and redundancy.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-18T03:24:58Z
      DOI: 10.1177/09544100231157132
       
  • A review of aircraft environmental control system simulation and
           diagnostics

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      Authors: Shafayat H Chowdhury, Fakhre Ali, Ian K Jennions
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      The aircraft Environmental Control System (ECS) enables the aircraft to maintain a comfortable and safe environment for its passengers throughout its operating envelope. The Pressurised Air Conditioner (PACK) is the heart of the ECS, and is composed of multiple sub-systems: heat exchangers, valves, compressor, turbine, and a water separator. The PACK’s principle function is to enable conditioning of the hot, high pressure bleed air from the engine or APU, for temperature, pressure and humidity against the cabin requirements. The operation of the PACK is governed by a control system which has the ability to mask degradation in its component during operation until severe degradation or failure results. The required maintenance is then both costly and disruptive. The PACK has been reported as major driver of unscheduled maintenance by the operators. The aviation industry is currently proactively exploring innovative health management solutions that aid the maintenance of aircraft key systems based on predictive based maintenance approaches using online condition monitoring techniques. This paper presents a comprehensive review of the simulation and diagnostic methodologies applicable to fault diagnostics of the ECS PACK. The existing literature suggests that model-based and data-driven methods are effective for conducting fault detection and isolation of the PACK system. The conceived findings indicate that the model-based diagnostic approach have been extensively employed to conduct PACK diagnostics at component level only. Their successful implementation requires robust experimental verification and validation against the actual data under healthy and faulty conditions. Although a substantial amount of work has been reported on developing first principles based simulation models and diagnostic strategies for the ECS, the acquired findings suggest that there is a compelling need for a verified and validated ECS simulation model to enable accurate PACK system-level diagnostics based on single and multiple component level degradation scenarios. It has also been identified that the existing literature lacks the evaluation of humidity regulation and the effect of the control system on the PACK performance characteristics. Finally, a taxonomy of diagnostic techniques and simulation models is compiled based on the available literature.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-17T07:31:58Z
      DOI: 10.1177/09544100231154441
       
  • The effects of spacing to diameter ratio on mixing characteristics of
           circular and elliptical twin jets

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      Authors: Ch Narendra Kumar, KP Sinhamahapatra
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Twin jets are encountered in many engineering and industrial applications, such as aircraft propulsion systems and combustors. Twin jets create a flow field that is more complex than a single jet due to its interaction with the individual jets. This paper investigates the effects of spacing to diameter (S/De) ratio and orientation on the mixing properties of circular and elliptical twin jets at four different S/De ratios of 1.25, 1.50, 1.75, and 2.0, respectively. The numerical simulations of twin jets are carried out with a jet Mach number of 0.8 using the Shear Stress Transport (SST) K-ω turbulence model. The results show that near the orifice exit, the twin jets are issuing into ambient conditions separately and resemble a free jet, leading to a potential core length independent of S/De. The merging and combined point locations change linearly from the exit with an increasing S/De ratio. The decay rate is higher for Twin Ellipse Minor than those in Twin Circle and Twin Ellipse Major, verified by a shorter converging region. In addition, near the jet exit, the spread rate is higher for Twin Ellipse Minor, which is consistent with the closer merging point location. The jet mixing is superior for twin minor elliptical configuration compared to twin circle and twin major elliptical jets at all S/De ratios.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-13T02:38:33Z
      DOI: 10.1177/09544100231155692
       
  • Force-torque (F-T) based multi-drone cooperative transport using fuzzy
           logic and low-cost and imprecise F-T sensor

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      Authors: Shraddha Barawkar, Manish Kumar
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      This paper presents a novel approach to perform the task of cooperative transportation (CT) by using multiple quadcopter drones. A leader-follower approach is utilized. Considering that the leader drone can be controlled using different means, such as Proportional, Integral, and Derivative (PID) control or remote control by an operator, this paper focuses on designing the control scheme for the follower drone. This paper specifically considers outdoor application of such systems that requires usage of Global Positioning System (GPS) to receive the positional information of the drones. However, GPS has inherent errors of order of magnitude that can destabilize the system. In order to address this major limitation, a Force-Torque Feedback Controller (FT-FC) is proposed to control the follower drone. The FT-FC provides control based on the interaction forces and torques acting at the point of contact between the follower drone and the payload. Using such passive control schemes, drones are thus not required to communicate with each other. Fuzzy Logic (FL) is used to implement the FT-FC. Fuzzy Logic provides effective force-torque coordination between drones, emulates human behavior during CT, and allows use of noisy inexpensive force-torque sensors. This paper presents results from numerical simulations showing the effectiveness of the proposed controller for way-point navigation and complex trajectory tracking. Additionally, the effectiveness of the fuzzy-based FT-FC in terms of handling disturbances is also demonstrated. The proposed FL FT-FC is also experimentally validated for two applications viz. three-dimensional physical Human Drone Interaction (HDI) and CT.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-08T09:30:00Z
      DOI: 10.1177/09544100231153686
       
  • High-dynamic intelligent maneuvering guidance strategy via deep
           reinforcement learning

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      Authors: Sibo Zhao, Jianwen Zhu, Weimin Bao, Xiaoping Li
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Aiming at the coordination between maneuvering penetration and high-precision guidance under complex flight missions of high-velocity vehicle, the manuscript studies a three-dimensional high-dynamic intelligent maneuvering guidance strategy based on optimal control and deep reinforcement learning (DRL). A three-dimensional attack–defense model is established, and maneuver guidance mission is decomposed into longitudinal and lateral directions. In the longitudinal direction, maneuvering model with the instantaneous miss distance as the control variable is constructed, and the maximum value principle is employed to obtain the optimal maneuver duration and start timing. In the lateral direction, Markov decision process model of maneuver guidance is proposed by synthesizing the guidance error and miss distance of encounter point, and the reward function is designed by considering maneuver and guidance performance. The DRL method is used to learn and train the maneuver strategy, and the training process is improved as well. The simulation results show that the intelligent maneuvering guidance strategy can improve the penetration performance, reduce influence of maneuver flight on the guidance accuracy, and ensure the adaptability under changeable flight missions.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-07T04:56:08Z
      DOI: 10.1177/09544100231155695
       
  • Numerical investigation of mixing performance for controlled supersonic
           jet

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      Authors: Bholu Kumar, Suresh Kant Verma, Shantanu Srivastava
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      In the present study, the mixing characteristics of the Mach 1.86 jet from a convergent-divergent nozzle of square cross-section from inlet to exit were investigated numerically. The jet studied were uncontrolled and controlled with limiting tab of rectangular and circular cross-sections. The nozzle pressure ratio is varied from 4 to 6 with a step size of one, leading to the confinement of the present study for the over-expansion and near correct expansion levels of the jet. It is observed that the core length, which is a direct indication of the extent of jet mixing, reduced significantly for the jet controlled with limiting tab as compared to that with the uncontrolled counterpart. Also, among the circular and rectangular limiting tabs, the tab with rectangular cross-section caused maximum core length reduction. The jet spread and the waves prevailing in the jet field were studied and visualized using pressure profiles and Mach contours, respectively. The present work may be used in understanding and solving complex phenomena occurring in the fields of aeroacoustics noise suppression, reduction of base heating of launch vehicles, supersonic combustion, mitigation of infrared radiations due to chimney smoke, etc., where jet mixing is highly desirable.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-03T12:32:55Z
      DOI: 10.1177/09544100231155574
       
  • Re-understanding and improvement of the pseudo-spectral method for rapid
           footprint generation

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      Authors: Zhao-ting Li, Rui-zhi He, Xiang-ji Tang, Hong-bo Zhang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      A PS (pseudo-spectral) method with improved parameters is proposed for the rapid footprint generation of reusable vehicles. Three aspects of the method were explored, including the consistency of the discrete NLP (Nonlinear Programming) problem with the original problem, the impact of the NLP problems' convergence accuracy on the results, and the final convergence accuracy factors. The reasonable ranges of the IPOPT solver’s convergence tolerance are redefined through these explorations. Furthermore, the solution process of the footprint is partially optimized. Finally, the results show that the method can fully improve the computational efficiency of solving the footprint using the PS method. The average time of each trajectory is minor than 0.9s, showing the parameter-improved PS method’s superiority.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-02T11:49:50Z
      DOI: 10.1177/09544100231153705
       
  • High-dimensional multi-objective optimization algorithm for combustion
           chamber of aero-engine based on artificial neural network-multi-objective
           particle swarm optimization

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      Authors: Shuang Liang, Lang Li, Ye Tian, Wenyan Song, Jialing Le, Mingming Guo, Shihang Xiong, Chenlin Zhang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      This paper considers optimizing the performance of high-temperature combustion chamber of an aero-engine based on a concentric and hierarchical model. First, sample data for the design variables are obtained based on Latin hypercube sampling method, and a one-dimensional program is used to obtain the true values of combustion efficiency and total pressure loss corresponding to each group of variables. The obtained data are then pre-processed to establish a dataset. Second, a multi-layer artificial neural network (ANN) architecture is designed and a surrogate model of the combustion-related performance of the combustor is established using a data-driven method. The results of global sensitivity analysis based on variance show that ratio of fuel flow to air flow (fuel–air ratio) and the total inlet pressure are the most important factors influencing the two objective functions. Finally, we optimize the multi-objective combustion-related performance of the surrogate model by applying the particle swarm optimization algorithm to it. The results of experiments show that the ANN-based model could accurately predict the efficiency of combustion and total pressure loss of the chamber, yielding root mean-squared errors of 0.0107 and 0.3032%, respectively. It also had better generalization ability than the cubic polynomial surrogate model. Compared with the cubic polynomial model, it generated an optimal Pareto solution set as prediction that had higher values in both objective functions. The proposed model might require better data that can be obtained using intelligent sampling methods so that deeper neural networks can be designed to reduce error and improve its optimization design.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-02T02:51:32Z
      DOI: 10.1177/09544100231154968
       
  • Air curtain as a SARS-CoV-2 spreading mitigation method in a small
           aircraft cabin

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      Authors: Krzysztof Kurec, Bartosz Olszański, Konrad Gumowski, Michał Klamka, Michał Remer, Janusz Piechna, Sławomir Kubacki
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      This paper discusses an application of air curtain for reduction of virus-laden droplets transmission from an infected host to other passengers in a small aircraft cabin. The study is restricted to respiratory droplets emitted during coughing. Discrete Particle Method introduced for violent respiratory events (VRE) captured in detail the movement of coughing puff inside the cabin and allowed to study the interaction of droplets with the air curtain’s stream and the surrounding air. The results show that the application of the air curtain inhibits the transmission process of small droplets (diameters ranging from 10 to 40 μm). The air curtain supplied with a limited air mass flow cannot alter the multiphase puff dynamics, but it can be utilized to deflect the virus droplets with lower momentum away from the neighboring passenger. Improved removal efficiency of virus-laden droplets has been achieved owing to the application of the air curtain together with supplementary suction surfaces introduced on the front seat backrest. The virus (SARS-CoV-2) transmission process was also analyzed by means of mass concentration of CO2 exhaled by the infected host, used as a contamination tracker. This part of the work aims at assessment of an applicability of CO2 tracer gas in analysis of virus transmission. Results show that CO2 tracer gas can only be employed for the study of small size droplets dispersion (diameter less or equal to 40 μm).
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-01T03:32:28Z
      DOI: 10.1177/09544100231153703
       
  • Effect of bend-induced inlet distortion on a centrifugal compressor
           performance and stall inception

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      Authors: Peng Wang, Ben Zhao, Qingjun Zhao, Jingtao Li, Liming Zhan, Wei Zhao
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Bend pipes are usually installed upstream of a centrifugal compressor because of spatial constraints. With the interaction between radial pressure gradient and centrifugal force in bend pipe, a pair of counter-rotating vortices (Dean vortices) is formed after the fluids passed through the bend, and the shape of Dean vortices keeps changing in the straight pipe between the bend and compressor. The effects of the changed Dean vortices on the aerodynamic performance and stall inception of a centrifugal compressor are investigated with an experimentally validated numerical method based on four models, in which the distance of the straight pipe located between the bend and the compressor varies from 0D to 1D through 1/4D and 1/2D. The results show that as the straight pipe length increases from 0D to 1D, both the total pressure deficit at compressor inlet and the flow separations at inlet pipe symmetry plane are enlarged, and the mass flow rate distribution of full-annulus become more fluctuant. As a consequence, the compressor aerodynamic performance degrades and its maximum flow capacity decreases. More importantly, bend-induced inlet distortion has the effect of inducing/suppressing impeller stall inception, it depends on the location and intensity of swirl distortion and total pressure distortion. The low total pressure region located at impeller tip leads to reversed flow and stall inception, while the positive pre-swirl component in swirl distortion decreases the incidence and suppresses stall inception. These results provide a reference for the design of upstream inlet curved pipes of centrifugal compressors.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-01T02:45:24Z
      DOI: 10.1177/09544100231154055
       
  • Design and performance evaluation of a novel H2/O2 electro-chemical hybrid
           thruster

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      Authors: Xiaoshun Wang, Chengren Zhao, Huijun Huang, Jinyong Fang
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      A H2/O2 electro-chemical hybrid thruster with a novel design for efficient coupling of hydrogen–oxygen detonation combustion and plasma acceleration is constructed and tested. The comprehensive effects of various parameters, such as the delay time, the background pressure, the capacitance, the external magnetic field, and the propellant mass flow rate, on the performance of the thruster have been explored in single-pulse mode. Several strategies for enhancing the efficiency have been proposed. It is found that, by adding an external magnetic field and decreasing the storage capacitor under the low pressure of 30 Pa and higher single-pulse gas intake at appropriate delay time, the average thrust and efficiency can be enhanced up to 73.2 mN and 15.58%, respectively. In addition, the maximal specific impulse of 676 s is also achieved. The results strongly indicate the great potential of the proposed electro-chemical hybrid thruster in achieving large thrust and high-level specific impulse.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-02-01T01:47:19Z
      DOI: 10.1177/09544100231155048
       
  • Conceptual aero-structural design of a fan stage under distorted flow

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      Authors: Manish Pokhrel, Darshan Sarojini, Dimitri N Mavris
      Abstract: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Ahead of Print.
      Rotor blades experience unsteady forces and aerodynamic losses when operating in a distorted inflow. The structural analysis of rotors under these conditions, therefore, is of prime importance during the early design phase. This work introduces a computationally efficient design framework that links the aerodynamic design and structural analysis of the rotor. Rotor structural analysis comprises computing dynamic stresses, the excitation frequencies, and resonance margins at various modes of vibration. A design space encapsulating fan stage design variables, aerodynamic performance, and rotor structural constraints is explored and optimized for maximum fan stage efficiency subject to aerodynamic and structural constraints.
      Citation: Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering
      PubDate: 2023-01-28T12:52:53Z
      DOI: 10.1177/09544100231153910
       
 
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