Characteristics and optimization of multi-body separation in supersonic ground effects

The electromagnetic launch of aerospace vehicles is an option for reusable earth/orbit space transportation in the future. In contrast to open space, complex ground effects emerge in supersonic near-ground multi-body separations. Here, the separation processes between a supersonic aerospace vehicle (traveling at Mach 1.5) and an electromagnetic sled were studied with a focus on the characteristics of the flow evolution and aerodynamic interference. The results show that the evolution of the supersonic near-ground separation can be divided into three substages: choked flows in the narrow gap, multi-body shock interactions and independent ground effect interference. The aerodynamic loads of the vehicle strongly correspond to the separation stages. The high-pressure region at the leading edge of the electromagnetic sled continuously sweeps the vehicle abdomen and causes significant fluctuations in the aerodynamic lift and moment, which play a dominant role in the separation trajectory. The altitude of the vehicle that flies away from the electromagnetic sled is relatively stable when the preset attack angle is 0° Following this separation, the vehicle has a pitch angle of -0.25° and tends toward a negative angle of attack. A vertical distance of 4.2 m is insufficient for optimal separation. Thus, the separation characteristics were optimized by combining the preset rudder deflection angle of 0° and inclined track with a slope angle of 1.5° Following this separation, the pitch angle of the vehicle is 3.4°, and the vertical distance increases to 14.8 m, which significantly improves the separation safety.