Numerical modeling of unsteady cavitating flow over a hydrofoil with consideration of surface curvature

Abstract

In the present study, a new partially averaged Navier-Stokes model based on a modified SST k-ω model (MSST PANS) is proposed with particular emphasis on the capability to predict the cavitating flow by considering the surface curvature effect. The unsteady cavitating flow around a NACA0015 hydrofoil is investigated by numerical simulation using the MSST PANS model, the SST k-ω model, and the SST k-ω PANS (SST PANS) model. Results indicate that the MSST PANS model predicts the more accurate cavitation shedding dynamics including the cavitation inception, development, split and collapse than the SST k-ω and the SST PANS models. The analysis using the vorticity transport equation depicts that the vortex dilatation and vortex baroclinic torque terms play the dominant role in producing the cavitating vortex during the inception and development of the cavitation. Further, the cavitating vortex shedding downstream induces severe pressure fluctuations on the hydrofoil surface near the trailing edge of the hydrofoil. The dominant frequency predicted by the MSST PANS model is in accordance with the frequency of the cavitating vortex evolution. The study confirms that the MSST PANS model is a promising method to simulate the cavitating flow over a hydrofoil with consideration of surface curvature, which performs more accurately with little increase of computational cost.