Hydrodynamics of the projectile entering the water under the ice hole constraint environment

Abstract

The study of the water entry of the projectile passing through the ice hole can solve the special issue of water entry under marine environmental constraints. We conducted experiments to validate the effect of the ice hole constraint on the dynamics of the water entry cavity and then used the numerical simulations to investigate the cavity dynamics of the projectile passing through ice holes with different sizes and rotation degrees. The results show that the ice hole affects the evolution of the water entry cavity and the motion state of the projectile. The splash crown flows back and then contacts the projectile surface when passing through the small-sized ice hole. Cavity collapses before the pinch-off. The splash crown flows back at the hole as the hole size increases, the cavity morphology is complete, and the projectile's movement is more stable at the initial stage of water entry and after deep cavity pinch-off. Special oblique jets form when passing through irregular holes. The impact of the oblique jet on the cavity increases as the rotation degree increases. The type of hole has little effect on the water entry dynamics of the projectile, but has a significant effect on the cavity morphology and the jet motion near the hole. The size of the hole has a great effect on the motion stability of the projectile.