Study on high-speed water entry of the projectile passing through an ice hole in a low-temperature environment based on a modified thermodynamic cavitation model

Abstract

It is a complicated problem to study high-speed water entry of a projectile passing through an ice hole in a polar environment. This involves the constraint of the ice hole on the free surface and low-temperature cavitation during the water entry. In this paper, a numerical method involving a modified thermodynamic cavitation model is introduced to study the water entry process. The numerical method is validated by comparing the numerical results of cavity evolution with the experimental data. The cavity dynamics of the projectile passing through the overwater ice hole at high speed and different ambient temperatures are studied. The cavity evolution, flow field, and motion state of the projectile are analyzed. The results show that a nested cavity forms when the projectile passes through the ice hole at high speed. The drop in temperature accelerates the surface closure and deep pinch-off. The effect of the temperature on cavity evolution weakens as the Froude number (Fr) increases. Moreover, at high Fr, the temperature alters the appearance of the ripple on the cavity surface and the growth trend of the cavity size. The drop in temperature reduces the content of the vapor in the cavity and changes the flow characteristics. At a low temperature, the hydrodynamic drag of the projectile passing through the ice hole increases, and the pressure distribution on the surface of the projectile is different.