RANS computations of a confined cavitating tip-leakage vortex

Cavitating tip-leakage vortices appear in several hydrodynamic flows such as marine propellers or Kaplan turbines. Cavitating computations are a challenging topic since several keys issues are an ongoing work such as the definition of a universal mass source term. The present study focuses on the computations of the tip-leakage vortex including the gap between the blade tip and the side wall. Two computations are performed, one without cavitation and a second one with cavitation. In both cases, the results are compared with experimental data. The cavitation influence is investigated by comparing the cavitating and the non-cavitating cases. A particular attention is focused on the vortex core trajectory, the vorticity field and the vortex core identification. It is shown that, compared to the non-cavitating case, cavitation leads to a vortex trajectory closer to the suction side and the side wall, which can be of importance regarding the cavitation erosion. Furthermore, cavitation modified the vorticity field in the vortex core region. The main feature is a misalignment between the high vorticity region and the cavitating region, which opens a discussion regarding the definition of the vortex core.