Numerical investigations on compressible thermal flows in high-speed water entry

The high-speed entry of a projectile into water involves numerous physical phenomena, with temperature playing a significant role in these. In this study, numerical simulations are used to study projectile water entry at 700 m/s under non-isothermal conditions, with the accuracy of the simulation method first being verified with experimental data. The entry process is divided into three stages: initial, intermediate, and complete. Initially, impact kinetic energy causes a sudden temperature increase, with the temperature distribution and shock waves exhibiting similarities. In the intermediate stage, thermal wake development and phase changes in the cavity formed by impact cause temperature variations. In the complete stage, the projectile becomes fully submerged, the thermal wake diminishes, and cavity expansion consumes energy, reducing both temperature and pressure. The air cushion phenomenon has a significant effect on pressure, but a relatively weak influence on temperature. Vortex monitoring reveals a decrease in tail temperature due to double-vortex cancellation, and relative flow within the cavity affects temperature changes. Velocity and temperature monitoring indicate a sharp increase, oscillation, and eventual stabilization in temperature. Cavitation-induced phase changes primarily drive temperature variations, while condensation of water vapor reduces temperature. This paper addresses the lack of considerations of thermal effects in previous studies of high-speed water entry, thereby providing a new perspective on this topic.