Characteristics of supercavitating flows around a hydrofoil

Supercavitation around a hydrofoil is studied experimentally to address the flowing characteristics. A high-speed video camera is used to visualize the flow structures under different cavitation numbers. The digital particle image velocimetry (DPIV) is employed to measure the velocity fields. The bubbles among the cavitating fields are used as the tracer particles to survey the velocity distribution inside the cavity and improve the tracking capability of the tracer particles. The results show that three distinct supercavitating flow regimes can be observed with the decreasing cavitation numbers, in which the cavitation structure varies with the distribution of the water-vapor mixing phase and vapor phase. A large velocity gradient exists around the interface between the cavitation area and the free stream. In the cavitation area, the lower-velocity region moves from the foil's middle part to the downstream with the decrease of the cavitation number. The fluid velocity is low in the water-vapor mixture region, while with the similar distribution in the free stream and the vapor region.