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861.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2023,71(5):2140-2154
After deployment from a rocket, a CubeSat is detumbled using magnetorquer rods bringing the norm to the point where the reaction wheels take over to reduce the angular velocity to null. Therefore, utilizing reaction wheels for satellite detumbling at higher initial velocities is vital but they are heavy and occupy significant space on a spacecraft having challenging control. To address this challenge, this paper features a disruptive approach that conducts the control only by the PCB-integrated magnetorquers with various geometries using a diverse non-unity track width ratio. The trace widths are parametrized such that the optimal torque to power dissipation ratio is investigated. The optimizations are then simulated for various geometric distributions and validated through comprehensive measurement setups that establish a framework for selecting the best-case coil configuration according to mission requirements. The detumbling rates of multiple asymmetric coil configurations are compared with the embedded designs in published literature and state of the art. It is found that the proposed asymmetric embedded magnetorquers can detumble the vehicle at high initial angular velocities. Lastly, the simulation results of thermal analysis are validated for selecting the application-specific optimal coils configuration. At the end, the proposed system is compared with the embedded magnetorquers available in the literature and commercial attitude control systems. 相似文献
862.
《中国航空学报》2022,35(12):102-116
Mechanically pumped two-phase loop (MPTL) which is a prominent two-phase heat transfer technology presents a promising prospect in thermal control for space payload. However, transient behavior of MPTL caused by phase-change and heat sources load-on/off in simulated space environment is rarely reported. In the present study, one MPTL setup was designed and constructed, and experimentally studied. Particularly, a novel two-phase thermally-controlled accumulator integrated with passive cooling measure and three capillary structures was designed as the temperature-control device. Dynamic behavior of the start-up, temperature control, and temperature adjustment were monitored; meanwhile, thermodynamic behavior within the proposed accumulator, the operating behavior as well as the heat and mass transfer behavior between the main loop and the accumulator were revealed. The results show that the fluid management function of the capillary structures for the novel accumulator is verified. The working point of the MPTL system can be adjusted by changing the temperature control point of the accumulator and it is little influenced by external heat flux and heat sources on/off. Pressure-drop oscillations which are manifested as fluctuations of temperature and pressure can be observed after phase changing due to the compressible volume within the accumulator and the negative-slope portion of the internal pressure. 相似文献
863.
The electro-hydrostatic actuator(EHA) used in more electric aircraft(MEA) has been extensively studied due to its advantages of high reliability and high integration. However, this high integration results in a small heat dissipation area, leading to high-temperature problems. Generally,to reduce the temperature, a wet cooling method of using the pump leakage oil to cool the motor is adopted, which can also increase the difficulty of accurately predicting the system temperature in the early desi... 相似文献
864.
865.
866.
《中国航空学报》2023,36(3):285-302
To improve the heat dissipation performance, this paper proposes a novel hybrid cooling method for high-speed high-power Permanent Magnet assisted Synchronous Reluctance Starter/Generator (PMaSynR S/G) in aerospace applications. The hybrid cooling structure with oil circulation in the housing, oil spray at winding ends and rotor end surface is firstly proposed for the PMaSynR S/G. Then the accurate loss calculation of the PMaSynR S/G is proposed, which includes air gap friction loss under oil spray cooling, copper loss, stator and rotor core loss, permanent magnet eddy current loss and bearing loss. The parameter sensitivity analysis of the hybrid cooling structure is proposed, while the equivalent thermal network model of the PMaSynR S/G is established considering the uneven spraying at the winding ends. Finally, the effectiveness of the proposed hybrid cooling method is demonstrated on a 40 kW/24000 r/min PMaSynR S/G experimental platform. 相似文献
867.
《中国航空学报》2023,36(3):212-219
Infrared camouflage based on artificial thermal metasurfaces has recently attracted significant attention. By eliminating thermal radiation differences between the object and the background, it is possible to hide a given object from infrared detection. Infrared camouflage is an important element that increases the survivability of aircraft and missiles, by reducing target susceptibility to infrared guided threats. Herein, a simple and practicable design is theoretically presented based on a multilayer film for infrared stealth, with distinctive advantages of scalability, flexible fabrication, and structural simplicity. The multilayer medium consists of silicon substrate, carbon layer and zinc sulfide film, the optical properties of which are determined by transfer matrix method. By locally changing the thickness of the coating film, the spatial tunability and continuity in thermal emission are demonstrated. A continuous change of emissive power is further obtained and consequently implemented to achieve thermal camouflage functionality. In addition, other functionalities, like thermal illusion and thermal coding, are demonstrated by thickness-engineered multilayer films. 相似文献
868.
869.
高速再入飞行器通常采用烧蚀防热材料作为外表面大面积的热防护材料。本文对两种蜂窝增强低密度硅基烧蚀防热材料的力学性能、热物理性能和烧蚀性能进行了测试,并结合试验结果对烧蚀机理进行了研究分析。结果表明,材料的密度越高、拉伸强度就越高,但拉伸模量相近;两种材料的隔热性能参数都较低。两种材料在不同热流密度条件下的电弧风洞烧蚀后退速率都较低,在部分烧蚀条件下有轻微膨胀。两种材料的烧蚀背温都较低,烧蚀表面形貌良好,能满足设计指标要求,是一种适用范围较广的烧蚀防热材料。 相似文献
870.
《中国航空学报》2023,36(5):250-267
Advanced civil aero-engines tend to adopt lean burn combustors to meet emission requirements. The exit of a lean burn combustor experiences highly non-uniformities in both temperature (Hot Streak, HS) and flow (swirl). This paper presents a numerical investigation on the behaviors of a High-Pressure (HP) turbine under a combined effect of swirl and hot streak. The investigation was conducted on a GE-E3 HP turbine with unsteady numerical simulations, which considered the realistic clocking position of the HP Nozzle Guide Vane (NGV) relative to the combustor. The influences of swirl orientations on the HS migration and thermal performances on the blade surface were examined. Results indicate that, inside the NGV passage, the swirl’s induced incidence angle effect dominates the HS radial migration. The transversal movement of HS follows the cross flow and thus makes itself approach the Suction Side (SS) and keep away from the Pressure Side (PS) as passing through the NGV, so that HS near the SS is more influenced by the incidence angle effect than that near the PS. As for the heat transfer, swirl affects the Heat Transfer Coefficient (HTC) on the NGV’s PS and SS mainly through the incidence angle effect. Different from the NGV, the inlet swirl and HS have limited effect on the HTC on the rotor blade’s PS, while on the rotor blade’s SS, the original vortex system dominates; therefore, the inlet non-uniformities merely enhance the HTC on the SS rather than alter its distribution characteristics. 相似文献