Cavitation CFD Prediction for NACA0015 Hydrofoil Flow Considering Boundary Layer Characteristics

The accuracy of cavitation CFD is not sufficient for the flow around very simple geometries such as single hydrofoil. The lift force and the cavity length are underestimated particularly for the high angle of attack cases. One of the possible reasons of the discrepancy is the singular characteristic of sheet cavitation in the boundary layers that is not taken into account in the recent cavitation models. It was observed that the sheet cavitation is not initiated in the laminar boundary layers. The inception and growth of the sheet cavitation occurs at the reattachment point of the laminar boundary layer separation or at the transition point of the laminar boundary layer to the turbulent boundary layer. These characteristics were reported in many literatures however they are not well modeled for cavitation CFD. In this paper the laminar boundary layer zone is identified for NACA0015 hydrofoil from the high speed video observation. Then, cavitation CFD is carried out by deactivating the cavitation model at the estimated laminar boundary layer zone. This modified cavitation CFD results are discussed and compared to conventional cavitation CFD results and measurement results.