Effects of Initial Separation Conditions on Submunition Motion During Multi-Body Separation in Near Space

Focusing on the complex aerodynamic interference and attitude response during multibody separation in the low-pressure and low-density environment of near space, a numerical investigation of the effects of different initial separation conditions on submunition motion is conducted. A three-dimensional unsteady flow model is established by coupling the six-degree-of-freedom rigid-body equations with the overset mesh technique. The effects of the free stream Mach number, initial angle of attack, initial separation velocity, and separation altitude on the motion characteristics of the submunition are systematically analyzed. The results show that, compared with conventional low-altitude conditions, aerodynamic forces have a weaker corrective effect on the separation motion and attitude in near space, making the initial separation parameters more influential. Increasing the free stream Mach number and initial angle of attack enhances the radial separation capability but intensifies the attitude response. As the separation altitude increases, the aerodynamic forces weaken, and the displacement and attitude variations in the submunition decrease accordingly. The initial axial separation velocity Vx0 has relatively little influence on the radial separation distance and pitching response. Increasing the initial radial separation velocity Vy0 increases the radial separation distance and reduces pitch oscillations, whereas increasing the magnitude of the initial lateral separation velocity Vz0 significantly amplifies the roll and yaw responses. The results provide a reference for the design of initial parameters for multi-body separation systems operating in near space.