Influence of Velocity on the Cavity Flow Characteristics of Vertical Ice⁃breaking Water Entry of a Projectile

Exploring the influence mechanism of ice sheet on the water-entry process of a high-speed projectile is of great significance for the development of advanced trans-media weapons suitable for ice-water areas. The processes of vertical ice-breaking water-entry of a high-speed cylindrical projectile at different initial velocities are studied based on the coupled Euler-Lagrange (CEL) method. The findings indicate that, when the initial velocity of projectile is relatively low (50 m/ s), the size of ice hole formed by impact is relatively small to severely hinder the influx of external gas, and the expansion and development of cavity are obstructed, leading to the premature neckingand early closure of cavity. Besides, there is no longer a surface closure phenomenon as no ice, and the deep closure of cavity occurs faster. When the velocity of projectile is higher (逸100 m/ s), the size of ice hole formed by impact is larger, allowing a continuous influx of external air and delaying the closure of cavity. The difference in scale between the ice sheet and the ice-free cavity decreases with the increase in initial velocity. Additionally, as the initial velocity of projectile increases, the interference of crushed ice on the airflow intensifies, thus enhancing the nonlinear and turbulent characteristics of flow field within the cavity. It is worth noting that the peak force of projectile entering water in an ice-free environment is 70% of that of ice-breaking water-entry (the ice thickness is half of the diameter of projectile) at the same speed. At a speed of 150 m/ s, a weak plastic strain occurs at the projectile head during the ice-breaking water-entry process, which should be emphasized to improve the structural strength of projectile head when designing new types of trans-media weapons used in ice-water areas. © 2024 China Ordnance Industry Corporation. All rights reserved.