Effect of velocity and angle on the structural evolution of cavity and flow field during vehicle water entry process

Research on vehicle water entry is crucial for enhancing the safety, performance, and survivability of vehicles in aquatic environments, particularly in scenarios such as amphibious operations, emergency landings, and naval applications. This study investigates the structural evolution of the cavity and flow field dynamics during vehicle water entry at varying velocities and angles using numerical simulations. The accuracy of the numerical method is validated through experiments, allowing for detailed analysis of air and vapor trajectories within the cavity. The results reveal that with the increase in velocity, the cavity changes from vapor to the mixed vapor and air cavity, and the flow field velocity increases proportionally. There is a cutoff velocity of 100 m/s that makes the water splash on both sides of the velocity evolve in reverse. A decrease in water entry angle causes air to enter the cavity, moving toward the dorsal side of the vehicle, which increases the air-vapor mixing area, with a higher concentration of vapor on the dorsal side during oblique entry. The finding of this work provides new insights into the evolution of multiphase fluids in high-velocity water entry.