Numerical simulation on the unsteady effect of solid rocket motor internal ballistic on aft part flow field of air-to-air missile

In the high-altitude working period of missile, the interaction between the supersonic external flow and the tail jet flow of solid rocket motor derives complex unsteady interactive flow at the tail of missile, which affects the working environment of aft missile. In order to explore the unsteady influence of the internal ballistics on the structure of aft missile, an unsteady CFD simulation model of double component gas was adopted to simulate numerically the integration flow field including the inner flow of nozzle and the outer flow of missile during the working period of motor. The structure of interactive flow field composed of multiple free shear layers, shock waves and expansion waves, as well as its changing process under the unsteady effect of internal ballistic and outer flow velocity, were studied. Based on it, the resulting influences of temperature and gas diffusion caused by interactive flow field on different parts of aft missile during different periods of motor internal ballistic were analyzed quantitively. The results show that the changing low-velocity vortex region generated by the unsteady interactive flow near the tail end of missile accelerates the temperature and gas diffusion of tail flow, erodes bottom region of aft missile in high temperature, and then lowers the working safety of aft missile structure. Therefore, it is necessary to consider it and decrease the working safety threats of unsteady influences caused by internal ballistic of solid rocket motor and missile outer flow in the design of aft part of air-to-air missile.