Transient cavitating vortical flows around a hydrofoil using k-omega partially averaged Navier-Stokes model

摘要

For accurate simulations of wall-bounded turbulent cavitating flows, the present paper proposed a partially averaged Navier Stokes (PANS) method derived from the k-omega turbulence model. Transient cavitating vortical flows around a NACA66 hydrofoil were simulated by using the k-omega PANS model with various filter parameters (f(k) = 0.2, 0.5 and 1, while f(w) = 1/f(k)) and a mass transfer cavitation model based on the Rayleigh Plesset equation. Compared with the available experimental data, the k-omega PANS model with f(k) = 0.2 can accurately reproduce the cavitation evolution with more complicated structures due to the reduction in the predicted eddy viscosity. Further analyses, using the vorticity transport equation, indicate that the transition of cavitation structure from two dimension to three dimension is associated with strong vortex cavitation interaction, where vortex stretching and dilation may play a major role. Therefore, the k-omega PANS model with the filter parameter of f(k) = 0.2 is an effective method to numerically predict the transient cavitating vortical flows around hydrofoils. The results obtained in this paper are helpful to provide a physical insight into the mechanisms of cavitation shedding dynamics.