Effect of Spinning Motion on Cavitation and Trajectory Characteristics of Projectile during Water Entry

A tailless supercavity projectile is launched by ship-borne artillery to kill underwater targets, such as torpedoes and frogmen, and the projectile spins at a high speed to maintain a stable trajectory in air. To study the effects of spinning on cavitation and trajectory characteristics of the projectile during water entry, a numerical model of the projectile flow field when entering water at a small angle and high spinning speed is established using the multiphase flow model and the overlapping grid technology. The supercavitation flow field and hydrodynamic characteristics of the spinning projectile and projectile without spinning motion entering water at different attitudes are calculated. The results show that the numerical models are in good agreement with the experimental results for the water entry load, rolling moment, and cavitation. The spinning motion promotes the occurrence of natural cavitation at the initial stage of water entry, the supercavity is asymmetric, and the spinning motion has no significant effect on the center of mass motion of the projectile during the water entry stage; the spinning motion restricts the pitch angle of the projectile, and is helpful in enhancing the horizontal motion stability.