Prediction of dynamic shedding of cloud cavitation on a 3D twisted foil and comparison with experiments

摘要

The paper presents a numerical study of shedding dynamics of the Delft 3D twisted hydrofoil in comparison with the experiment by Foeth and Terwisga (2006). It uses a single-fluid multiphase mixture flow RANS method in connection with Singhal et al's full cavitation model and a modified RNG k-e turbulence model. The modification made to the turbulence model addresses the influence of compressibility effect on turbulence by artificially modifying the turbulent viscosity and takes effect only in the compressible mixture flow regime. The results obtained by the present method are encouraging since the behaviour of the re-entrant jet flow and the main features of shedding dynamics resemble well with those observed in the experiment. The shedding frequency, Strouhal number and lift coefficient are quantitatively comparable with the measurement data. Particularly, the numerical results show also that the transversal velocity component of the re-entrant jets is of crucial importance for the shedding in this particular case with a convex shaped cavity closure line. It is also seen that there is a vortex generation in the closure region of the sheet cavity.