组合动力空天飞行器是未来天地输运系统的重要发展方向。借助电磁助推起飞是解决空天飞行难题的新兴技术途径。针对电磁近地助推分离存在的风险，以腹式进气两级入轨飞行器Stargazer为研究对象，采用经近地多体干扰风洞试验校验的数值方法，研究了其在马赫数1.6自由空间内的基础特性和分离流场结构，并探究了离地高度和电磁制动加速度对分离安全性的影响规律。结果表明，腹式进气飞行器近地分离流动的独特性体现在壅塞阶段，期间进气道在叠加近地激波反射和电磁助推级激波干扰后壅塞加剧，存在分离泡和激波的生成、消退，导致飞行器迅速抬头；在多体干扰和独立地面效应阶段，受助推级头部激波低头冲击和轨道面反射激波影响，飞行器转而持续低头。因此，整个分离过程存在严重风险。改变离地高度会直接改变地面反射激波对飞行器下表面的作用位置，进而影响分离安全性：增加离地高度至0.3倍飞行器全长，激波结构能够减弱前期抬头速度和后期低头速度，导致分离结束后，垂向间距12.4 m，俯仰角-5.3°，最大垂向过载7.6g，满足安全性条件。制动加速度主要通过改变助推级干扰阶段和独立地效阶段的时长以影响分离过程，选取150~200 m/s²进行制动有效平衡了两阶段的干扰利弊，使分离轨迹满足预期目标。

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.