Numerical simulation research on opposing jet interaction characteristics of rocket inverse flight

Powered vertical recovery is one of the key technologies to realize the reusable launch vehicles. The rocket's backward flight will create a huge separation irregular flow throughout the vertical recovery process, and complicated aerodynamic interference will result from the engine's reverse jet interacting with the mainstream. These pose serious challenges to numerical simulation methods. Based on NNW-FlowStar software and unstructured hybrid grid technology, the numerical method was validated using the ball head opposing jet model and the self-developed rocket opposing jet wind tunnel test model. The interference characteristics of different double jet states on the opposing jet flow of the rocket are studied. The study demonstrates that the NNW-FlowStar is more capable of simulating the interference features of a rocket's reverse flight, and the findings of the numerical simulations correlate well with the test results. Different combined jet forms show different jet interference characteristics and flow field structures. The axial force of different jet schemes varies significantly, which also has a great impact on torque characteristics and even leads to changes in the longitudinal static stability of the whole rocket body. In the supersonic flow state, the deceleration effect is best in the second double injection state.