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Authors:Wang; W., Huang, K., Zhao, F. Pages: 1659 - 1675 Abstract: The high-frequency and high-amplitude pyroshock environment during the service of the spacecraft will cause damage to the equipment. Here, we develop a shock test device based on air cannon to simulate the above pyroshock environment. Then, a finite element model was established by explicit dynamic software ANSYS/LS-DYNA, and the simulation results were proved to be consistent with the test data. Based on the theory of Shock Response Spectrum (SRS), the effects of device parameters such as pressure, bullet material and resonant plate material on SRS were investigated via numerical simulation and shock test. This study shows that the amplitude of SRS increases with the increase of pressure in the range of 0.15–0.60 MPa, and the break frequency amplitude has a square root function relationship with the pressure. Additionally, the high-frequency amplitude of SRS was affected by the energy transfer efficiency of the bullet. PubDate: 2023-04-14 DOI: 10.1017/aer.2023.22
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Authors:Qian; Y., Wang, Z., Gursul, I. Pages: 1676 - 1697 Abstract: Lift alleviation by a mini-spoiler on aerofoils, unswept and swept wings encountering an isolated counter-clockwise vortical gust was investigated by means of force and velocity measurements. The flow separation region behind the spoiler remains little affected during the gust encounter. The maximum lift reduction is found for the static stall angle of attack. The change in the maximum lift during the gust encounter is approximately equal to that in steady freestream. The comparison with plunging aerofoils reveals that, for the same maximum gust and plunge velocity, the effectiveness of the mini-spoiler is much better in travelling gusts. This reveals the importance of the streamwise length scale of the incident gust. For the unswept wing, there is some three-dimensionality of the flow separation induced by the mini-spoiler near the wing tip. The magnitude of the lift reduction can be estimated using the aerofoil data and by making an aspect ratio correction for the reduced effective angle of attack. For the swept wing, the mini-spoiler can disrupt the formation of a leading-edge vortex induced by the incident vortex on the clean wing and can still reduce the maximum lift. PubDate: 2023-04-05 DOI: 10.1017/aer.2023.26
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Authors:Sun; P., Liu, C. Pages: 1698 - 1716 Abstract: Leakage, deformations, power loss, heat generation in the support seal system and other issues are typical when support seals are developed. The design of the support seal system has progressively evolved over recent decades as part of an ongoing effort to provide effective cooling for the aero engine secondary air system. In particular, oil heat management in the oil chamber has strict requirements, which limit the heat generation of the support seal system. The potential of supporting seal research with an oil system is investigated in this work. The combination of the CFD/FEA method and quantifying the heat generation entering the oil chamber allows for improvements not just to the individual buffer air seal unit, but the oil seal together. The analysis relies on the combination of quantifying heat generation entering the oil chamber to provide a mutual influence of neighbouring labyrinth seals. The mutual influence requires further analysis, considering the thermal deformation of the rotor/stator to provide further accurate geometry parameters in preliminary seal designs. The experimental test was conducted to verify the preliminary CFD-FEA loosely coupled analysis result, which reveals that in a turbine support seal system, the radius of the buffer air seal has a significant influence on the leakage flow rate and power loss of the oil seal, which should take into account the integral influence of the pressure difference of the oil seal caused by the radius change of the buffer air seal and the running clearance of the oil seal. PubDate: 2023-06-05 DOI: 10.1017/aer.2023.31
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Authors:Rechtik; S., Daoud, F. Pages: 1717 - 1736 Abstract: In an aircraft design, optimisation has become a common practice, especially when structural and aerodynamics interactions are considered. Performance measures often used in an industrial setting include structural weight, drag, lift to drag ratio, fuel burn or maximum range. It is a common practice to evaluate such performance indicators only on a handful of sample points. To achieve a truly economical aircraft design it is necessary to include a fully integrated mission analysis during a multidisciplinary structural optimisation, as there is a strong coupling between a flight behaviour and actual operational conditions of an aircraft. This paper makes a case for a modular approach to a mission analysis implementation that could utilise a variety of physical models and their combinations, offsetting some of the computational demands related to a fully integrated mission analysis and allowing to focus resources where they are needed. PubDate: 2023-04-03 DOI: 10.1017/aer.2023.21
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Authors:Zhang; X., Liu, S., Yan, J., Liu, S., Yan, B. Pages: 1737 - 1751 Abstract: Collaborative planning for multiple hypersonic vehicles can effectively improve operational effectiveness. Time coordination is one of the main forms of cooperation among multi-hypersonic glide vehicles, and time cooperation trajectory optimisation is a key technology that can significantly increase the success rate of flight missions. However, it is difficult to obtain satisfactory time as a constraint condition during trajectory optimisation. To solve this problem, a multilayer Perceptrona is trained and adopted in a time-decision module, whose input is a four-dimensional vector selected according to the trajectory characteristics. Additionally, the MLP will be capable of determining the optimal initial heading angle of each aircraft to reduce unnecessary manoeuvering performance consumption in the flight mission. Subsequently, to improve the cooperative flight performance of hypersonic glide vehicles, the speed-dependent angle-of-attack and bank command were designed and optimised using the Artificial Bee Colony algorithm. The final simulation results show that the novel strategy proposed in this study can satisfy terminal space constraints and collaborative time constraints simultaneously. Meanwhile, each aircraft saves an average of 13.08% flight range, and the terminal speed is increased by 315.6m/s compared to the optimisation results of general purpose optimal control software (GPOPS) tools. PubDate: 2023-04-26 DOI: 10.1017/aer.2023.24
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Authors:Idrissi; O., Bikir, A., Mansouri, K. Pages: 1752 - 1773 Abstract: Nowadays most busy international airports and their corresponding terminal areas are suffering from huge congestion issues due to the simultaneity of their arrival aircraft. The aim of this paper is to establish a new separation method using time- based-separation, speed modification during approach phases and Point Merge System (PMS) so as to ensure efficiently the traffic flow. This work took as a case study the busiest airport of Morocco, The Mohammed V International airport of Casablanca. The proposed management model offers very good results when compared with other models such as the first-come first-served (FCFS) model. PubDate: 2023-04-12 DOI: 10.1017/aer.2023.20
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Authors:Wang; K., Wang, J.Y., Huang, H.X., Xie, L.R., Liu, Y., Tan, H.J. Pages: 1774 - 1792 Abstract: The unstart phenomenon of supersonic inlets caused by backpressure is dangerous for aircraft during flights because it severely reduces the air mass flow rate through the engine. We used unsteady numerical simulations to evaluate the unstart and restart characteristics of a two-dimensional supersonic inlet during rapid backpressure changes. The effects of the depressurisation time and depressurisation value on the inlet flow characteristics and restart features are discussed. The results show that the depressurisation time affects the restart procedure when the back pressure drops from the inlet unstart value to the normal working state value. When the depressurisation time decreases, it becomes easier for the inlet to restart. However, the inlet cannot restart if the depressurisation time is too long. When the depressurisation time and value were large enough, a short buzz period occurred before the inlet restarted. Both the time and value of depressurisation affected the restart characteristics. PubDate: 2023-04-20 DOI: 10.1017/aer.2023.19
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Authors:Zheng; H., Zhou, Z., Liu, L. Pages: 1793 - 1816 Abstract: The boundary layer thickness on a compressor blade suction surface increases rapidly under a adverse pressure gradient and even separates from the blade surface. This paper proposes a novel method for developing the slot inside the blade, with the inlet of the slot located at the leading edge of the blade and the outlet located at the suction surface, using the momentum of the incoming flow to form a high velocity jet to control the boundary layer on the suction surface. For a plane cascade with a diffusion factor of 0.45, the effects of the main slot parametres (such as the shape of the slot and the positions of the slot inlet and outlet) on the flow in the slot, the flow field and the aerodynamic performance of the cascade were investigated with a numerical method. When the aerodynamic performance of cascades with slotted and unslotted blades was compared, it was found that a reasonable slot structure can effectively inhibit the development of the boundary layer on the blade suction surface and greatly improve the aerodynamic performance of the cascade. Based on the influence of the slot parametres of the above cascade, the slot of a plane cascade with a diffusion factor of 0.60 was designed. The numerical calculation results show that the slotted cascade with a diffusion factor of 0.60 outperformed the slotted cascade with a diffusion factor of 0.45. This result showed that the higher the cascade load, the greater the performance improvement from slotting. Furthermore, the unslotted and slotted cascades were tested, and the test results agreed well with the calculations. The aerodynamic performance of the slotted cascade was better than that of the unslotted cascade, which verifies the accuracy of the calculation method and the feasibility of blade slotting for suppressing the development of boundary layers on suction surfaces and reducing flow loss. PubDate: 2023-08-03 DOI: 10.1017/aer.2023.67
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Authors:Bektas; O. Pages: 1817 - 1831 Abstract: The purpose of this paper is to group the flight data phases based on the sensor readings that are most distinctive and to create a representation of the higher-dimensional input space as a two-dimensional cluster map. The research design includes a self-organising map framework that provides spatially organised representations of flight signal features and abstractions. Flight data are mapped on a topology-preserving organisation that describes the similarity of their content. The findings reveal that there is a significant correlation between monitored flight data signals and given flight data phases. In addition, the clusters of flight regimes can be determined and observed on the maps. This suggests that further flight data processing schemes can use the same data marking and mapping themes regarding flight phases when working on a regime basis. The contribution of the research is the grouping of real data flows produced by in-flight sensors for aircraft monitoring purposes, thus visualising the evolution of the signal monitored on a real aircraft. PubDate: 2023-09-04 DOI: 10.1017/aer.2023.71
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Authors:Zhao; Y., Yuan, Y., Chen, R., Yan, X. Pages: 1832 - 1849 Abstract: Although a coaxial compound helicopter can takeoff without propeller in the normal condition, the distance should be as short as possible for obstacle avoidance when the vehicle operates in a confined area with heavy loads. Therefore, a suitable propeller control is required to improve the takeoff performance while the total power consumption is no more than the available power. The path is predicted by applying trajectory optimisation. Several varying takeoff parameters, including attitude, liftoff speed and obstacle height, are considered for optimum global performance. Three path indicators are proposed. Apart from typical distance and pilot workload, path sensitivity is quantified based on deviation from takeoff parameter variation. Results indicated that low propeller thrust at hover and moderate allocation on the propeller through flight is recommended. The aircraft achieves significantly improved takeoff performance compared to flight with pure rotors while maintaining the maximum takeoff weight. The distance is shortened by 12.6%, and the longitudinal pilot workload is alleviated by 9.8% and 7.3% from mean and maximum power frequency aspects. Besides, the path is less sensitive to takeoff parameter variations, such as speed, altitude and height. PubDate: 2023-03-16 DOI: 10.1017/aer.2023.7
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