LES investigation into the cavity shedding dynamics and cavitation-vortex interaction around a surface-piercing hydrofoil

Abstract

Recent experiments have found that there is unstable vaporous cavitation around a surface-piercing hydrofoil at high Froude numbers and small yaw angles, and it would promote ventilation formation [R. Huang et al., "Investigations into the ventilated cavities around a surface-piercing hydrofoil at high Froude numbers,"Phys. Fluids 34, 043304 (2022)], but the cavity shedding dynamics and the mechanism of cavitation-vortex interaction are still open problems. In this paper, the unstable vaporous cavities around a surface-piercing hydrofoil are numerically investigated using the large-eddy simulation coupled with the Schnerr-Sauer cavitation model. Numerical simulations can predict the cavity features, including an aerated base cavity aft of the hydrofoil trailing edge, vaporous cavitation at the hydrofoil suction surface, and tip-vortex cavitation. A U-shaped vapor cloud shedding together with a horseshoe vortex is observed during the unsteady cavitation evolution, that is, the cavity development, cutoff, and collapse. This irregular shedding is related to the three-dimensional reentrant jet induced by the velocity reflection at the vaporous cavity closure line. Furthermore, the effects of the vaporous cavitation on the vorticity generation are attributed to vortex stretching, baroclinic torque, and vortex dilatation by using the vorticity transport equation. This study could contribute to the novel hydrofoil designs and their flow control.