摘要
利用电磁助推将空天飞行器在地面加速至超声速发射,能够规避低速起飞阶段,对宽速域飞行提供了一种颇具潜力的解决方案。到达发射的目标速度,飞行器与电磁橇在近地面效应的干扰下能否实现安全分离是电磁发射的关键环节之一。针对近地超声速多体分离问题,采用非定常流动数值模拟方法对马赫数1.6状态下飞行器-电磁橇分离过程中的流动干扰情况进行了数值模拟。结果表明:超声速近地分离过程可分为3阶段,依次是窄间隙壅塞流阶段、多体联动干扰阶段和独立地面效应干扰阶段,第1阶段以飞行器-电磁橇窄间隙内激波多重反射现象和局部壅塞效应为特征,第2阶段以飞行器与电磁橇快速联动下的干扰为特征,由双向干扰演变为飞行器对电磁橇单向干扰,在第3阶段飞行器与电磁橇均受独立的地面效应干扰。飞行器和电磁橇的气动载荷变化与分离流场所处阶段具有相关性。电磁橇前缘高压区由飞行器腹部掠过尾部导致飞行器气动阻力和升力陡然降低,力矩由低头力矩向抬头力矩转变剧烈。飞行器尾流膨胀区和尾激波相继扫掠电磁橇,导致其升力系数先增加至正升力后降低至负升力。整体上,飞行器飞离电磁橇的姿态较为平稳,两者在垂向和纵向上的间距持续增加。
Accelerating the aircraft to supersonic speed on the ground by using electromagnetic boosting can avoid the low-speed takeoff phase, and provides a potential solution for wide-speed-range flight. The Mach number 1. 6near-ground multibody free separation process is comprehensively investigated by numerical simulation. The results show that the evolution of supersonic near-ground separation can be divided into three stages, namely, choked flow in the narrow gap, interference induced by multi-body linkage, and independent ground effects. The first stage is featured by multiple reflections of shock waves and local choked flows in the gap between the aircraft and the electromagnetic sled. In the second stage, the flow evolution can be divided into two sub stages: bidirectional interference between the aircraft and the electromagnetic sled, and unidirectional interference from the aircraft to the electromagnetic sled. In the third stage, both the aircraft and the electromagnetic sled are subject to independent ground effects interference. Aerodynamic characteristics of the aircraft and the electromagnetic sled are strongly correlated with the separation stage. The high-pressure region at the leading edge of the electromagnetic sled sweeps past the rear of the aircraft, causing the aerodynamic drag and lift of the aircraft to decrease sharply and the moment to change dramatically from downward force moment to upward force moment. The expansion region and the shock wave in the wake of the aircraft subsequently sweep the electromagnetic sled, causing its lift to first increase to positive lift and then decrease to negative lift. Overall, the attitude of the aircraft flying away from the electromagnetic sled is relatively stable, and the distance between the two continues to increase in both vertical and longitudinal directions.
作者
李少伟
宁昕
罗星东
侯自豪
薄靖龙
LI Shaowei;NING Xin;LUO Xingdong;HOU Zihao;BO Jinglong(School of Astronautics,Northwestern Polytechnical University,Xi'an 710072,China;Institute of Magnetic Levitation and Electromagnetic Propulsion,China Aerospace Science&Industry Corporation,Beijing 100074,China)
出处
《航空学报》
EI
CAS
CSCD
北大核心
2024年第18期111-122,共12页
Acta Aeronautica et Astronautica Sinica
关键词
电磁发射
空天飞行器
超声速地面效应
近地分离
多体干扰
electromagnetic launch
aerospace vehicle
supersonic ground effect
near-ground separation
multi-bodyinterference
