Numerical Calculation of Water Exit Process of Supercavitating Vehicles under Different Sailing Conditions

Abstract

The water exit process of vehicles is very complicated, accompanied by multiphase flow, cavitation, phase transition, and turbulence instability, and the applied force is highly unsteady and nonlinear. At present, studies on the water exit problem of the vehicle with cavitation focus on the vertical or oblique water exit, emphasizing the trajectory and attitude of the vehicle. There are few studies on the water exit process of the supercavitating vehicle. In this paper, based on STAR-CCM+ software, overlapping grid technology was used for meshing, and the volume of fluid(VOF) model was used to capture the gas-liquid interface. The Schnerr-Sauer model described the cavitation process around the vehicle, and a numerical calculation model of the water exit process of the vehicle was established. The water exit process of the vehicle under different sailing conditions(initial velocity, initial water depth, and ventilation) was simulated and calculated, and the flow field and cavity evolution laws under different conditions were obtained. The hydrodynamic and kinematic characteristics of the supercavitating vehicle were analyzed. The simulation results show that the underwater motion of the vehicle with different initial velocities presents two different modes. Under different water depths, the initial cavity number is different. Cavity around the vehicle is more likely to rupture in deeper waters. The cavity morphology can be improved effectively by increasing the ventilation.

Keywords

• supercavitating vehicle
• water exit
• overlapping grid