Analysis on the evolution of cavitation and flow field of vehicles entering water vertically at high speed

A numerical method is developed to consider the effects of fluid force and structural deformation on the flow field. The accuracy of the method is verified by experiments. The cavity evolution process are studied, and the characteristics of the velocity and vortex in the calculated flow field region are analyzed. The motion process of the dynamic wall of the cavity around the vehicle is simulated, and the phenomena of vortex distribution in the wake of the vehicle, instability in the wake of the cavity, and multistage closure of the cavity wall are obtained. It is revealed that the closing of the cavity will cause the velocity of the flow field inside the cavity to be reduced, and the return jet generated by the closing of the cavity will hit the vehicle and cause its attitude to be deflected. The peak velocity of the cavity wall appears at the position of cavity closure and the position of head cavity generation. The vortex scale around the vehicle gradually increases from the head of the body towards the top of the water surface. The research in this paper provides reference for the design of water entry vehicle.