Experimental and numerical investigations of unsteady tip leakage vortex cavitating flows around a hydrofoil

Experimental and numerical investigations were conducted to highlight the unsteady tip leakage vortex cavitation flow in a hydrofoil tip region. The experiments were conducted in a closed cavitation tunnel, which a high-speed-camera had been put into using to observe the cavitation patterns. A new cavitation model, which takes into account the effects of vortex on mass transfer process in cavitation, is utilized for the computations of developed tip leakage vortex cavitating flow. Good agreement is observed between the numerical predictions and experimental observations. The results show that unsteadiness of the leading edge attached cavity would significantly change the pressure on the suction side, which is the main reason for the unsteadiness of the shear layer cavitation. The pressure fluctuation at the end of the attached cavity would induce the change of the tip leakage vortex circulation. Furthermore, the breakup of the leading edge cavitation would induce a local high pressure in the suction side, resulting in the decreasing of the circulation of the tip leakage cavitating vortex.