关键词: 电磁助推, 空天飞行器, 超声速地面效应, 分离, 进气道, 离地高度, 制动加速度

Abstract:

The aerospace vehicle with combined power is an important development direction for future space transportation systems. Using electromagnetic propulsion for aerospace vehicle takeoff is a new emerging technological approach to solving the problem of aerospace flight. In response to the risks associated with electromagnetic propulsion separation in ground effect， the Stargazer， a two-stage-to-orbit vehicle with abdominal intake， was taken as the research object. Numerical methods verified by multi-body interaction wind tunnel tests in ground effect were used to firstly study the basic aerodynamic characteristics and typical separation flow structures of the Stargazer under Mach number 1.6. Subsequently， the impact of ground clearances and electromagnetic braking accelerations on separation safety was investigated. The results show that the uniqueness of separation flow of the vehicle with abdominal intake is reflected in the choked flow stage， where the choked air inlet is further congested by the ground reflected shock waves and shock waves during the electromagnetic assisted stage. There are also separation bubbles and the generation and dissipation of shock waves during the separation process. Due to this influence， the aircraft quickly pitches up. In the stages of multi-body interference and only ground effects， the aircraft gradually pitches down due to the impact of the electromagnetic assisted stage bow shock wave and ground reflected shock waves. Therefore， there is a serious separation risk throughout the entire separation process. The height above ground affects the separation safety by changing the positions of the reflected shock waves on the aircraft， and the shock wave structures at a ground clearance of 0.3 times of total length can restrain the speed of pitching up in the early stage and the speed of pitching down in the later stage. At the end of separation， vertical spacing is 12.4 m， pitch angle is -5.3°， the maximum vertical overload is 7.6g， satisfying safety conditions. The braking acceleration mainly affects separation safety by changing the interference time of the electromagnetic assisted stage and only ground effect stage. Choosing 150–200 m/s² for braking can well balance the advantages and disadvantages between the two stages， and the separation trajectories satisfy expectations.

Key words: electromagnetic propulsion system, aerospace vehicle, supersonic ground effect, separation, air inlet, ground clearance, braking acceleration