Ballistic Characteristics of High-Speed Projectiles Entering Water Vertically

The formation of supercavitation after a high-speed projectile enters water has a decisive impact on the underwater ballistic and penetration of the projectile. In this study, Ansysfluent۱۹.۰ simulation software is used to study water entry of a chosen projectile at velocities of ۳۰۰, ۴۰۰, ۵۰۰, and ۶۰۰ m/s. The underwater cavitation characteristics, trajectories, and flow-field characteristics are analyzed for a ۵.۸-mm caliber conical flat head projectile, as well as for t wo other projectiles of the same caliber and different head shapes — conical cone head and elliptical flat head — entering water vertically at the same velocities. The attenuation rate of water entry velocity increases with the increase of velocity. Within first ۳ms, the velocity attenuation rate of the conical flat-head projectile with a water entry velocity of ۶۰۰m / s is ۵۵.۶ %, while the velocity attenuation rate of the projectile with a water entry velocity of ۳۰۰m / s is only ۱۶.۳ % within ۳ms. Among the head shapes considered, the conical flat head projectile is the most stable for vertical water entry. The stability of an elliptical flat head projectile is worse, and the trajectory stability of a conical cone head projectile is still worse