On the Capability of a RANS Method to Assess the Cavitation Erosion Risk on a Hydrofoil

This paper aims at an assessment of the cavitation erosion risk by using a contemporary unsteady RANS method in conjunction with post-processing procedures, without the necessity to compute the details of the actual collapses. Such a procedure is developed from detailed investigations on the flow over hydrofoils.
The first objective is to get a better understanding of the unsteady cavitation dynamics over hydrofoils and the physics that may lead to a high risk of cavitation erosion. The capability of the multiphase RANS method to predict the relevant and critical unsteady cavitation dynamics is examined on a NACA0015 hydrofoil. It is found that the large-scale structures and typical unsteady cavitation dynamics predicted by the RANS method are in fair agreement with the experimental observations.
The second objective is to find a methodology for the assessment of the risk of cavitation erosion on the surface of hydrofoils by using unsteady RANS simulations as input. A new erosion intensity function is proposed based on the mean value of the time derivative of the local pressure that exceeds a certain threshold. The evaluation on a NACA0015 hydrofoil shows that a good correlation is found between the locations with a computed high erosion risk and the damage area observed from paint tests.