Observations and numerical simulations of unsteady partial cavitation on 2-D hydrofoil

Abstract

In present paper, experimental observations and numerical simulations are used to understand some flow mechanism of partial cavity, such as the instability of attached sheet cavitation and the relations between cloud cavitation and erosion. NACA0012 and NACA16012 hydrofoils were employed both as the test model in the cavitation tunnel experiments and the model for numerical simulations. The high-speed video camera and TR-PIV system was used in the experiments. The re-entrant jet was captured successively in experiment and the mechanism that the re-entrant jet induced the break-off of cavity is validated. In numerical simulation, Reynolds-Averaged Navier-Stokes equations with the cavitation model of Transport Equation Model (TEM) were developed. The cavity morphology, flow structure, instability and developing process, were investigated. The numerical results showed that re-entrant jet is not absolutely constituted by liquid but vapor/liquid mixture, and the breakoff process of sheet cavitation is directly induced by re-entrant jet closely along the wall. The calculating shedding frequencies are very close to the experimental data.