超 声 速 电 磁 发 射 近 地 多 体 分 离 气 动 干 扰 特 性

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. 6 near-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.