Experimental Observations of Cavitating Flows Around a Hydrofoil

The cavitation around a hydrofoil is studied experimentally to shed light on the muhiphase fluid dynamics. Different cavitation regimes are studied by using high speed visualization and particle image veloeimetry（PIV）. As decreasing the cavitation number, four cavitating flow regimes are observed： incipient cavitation, sheet cavitation, cloud cavitation, and supercavitation. From the incipient cavitation to the cloud cavitation, bubbles become more and more. Phenomena with large-scale vortex structure and rear re-entrant jet associated with the cloud cavitation, and subsequent development in the supercavitation are described. The velocity in the cavitation regions in the different cavitation conditions is low compared to that of the free stream. The large velocity gradient is also observed in the cavitating flow region near the surface of the hydrofoil.