Analysis of Effects of Speed on Oblique Water Entry Process of a Cylinder Under Ice-Hole Constraint

Supercavity technology has received extensive attention from scholars at home and abroad in recent years. The polar ice region is bound to have a significant effect on the cavity evolution and motion characteristics of supercavitating projectiles. For the water entry problem of supercavitating weapons in an ice environment, a numerical method for the oblique water entry cylinder under ice-hole constraint is established based on the N-S equations by introducing the VOF model and combined with the overlapping mesh technique. On this basis, the numerical simulation of the water entry process of the cylinder through the ice hole under different velocities is carried out, and the cavity evolution and impact characteristics of the cylinder in the water entry process are analyzed. The results show that ice-hole constraint restricts the flow of water in the ice hole such that direct contact between the cavity wall and the ice-hole wall results in a curved cavity wall on the water-away side. At the same time, the ice hole constraints increase the cylinder impact load, which accelerates the underwater velocity decay of the cylinder and contributes to a larger deflection angle of the cylinder than in the ice-free environment. However, as the velocity of the cylinder into the water increases, the water-away side wall bends to an essentially similar extent due to the near-wall effect. Moreover, the impact load of the cylinder into the water increases, resulting in a faster decay of the underwater velocity of the cylinder, as well as a gradual increase in the deflection angle. The influence law of water entry velocity on the cavity evolution and motion characteristics under the ice-hole constraint can provide a certain reference basis for the stability of water entry of polar supercavitating weapons.