Study on the cavity evolution and load characteristics of large projectile during high-speed water entry

The evolution mechanism of cavity flow field, impact load and structural response characteristics during high-speed water entry of large projectile were studied by using fluid-structure interaction (FSI) numerical method, which was used to simulate process of high-speed water entry under different conditions. The results show that, during high-speed water entry of large projectile, the greater the Froude number (Fr) of water entry, the more intense the cavitation, and the lower the degree of cavity development at the certain time. The smaller the water entry angle, the later the surface seal time, the more obvious the cavity asymmetry. With a small negative attack angle, surface closure is more likely to occur, while with a large negative attack angle and positive attack angle, surface closure will be delayed or even disappear. The stress is concentrated on the center and edge of the top of the projectile, and the plastic deformation is large. With the increase of water entry Fr and angle, the maximum value of stress, strain and deformation increases. With the angle of attack from negative to positive, the maximum stress, strain and deformation decrease, and the stress distribution between negative and positive angles of attack is symmetrical.