Experimental observations of inception cavitation vortices around a hydrofoil

The inception cavitation around a 2D-hydrofoil in the boundary layer of a non-separated turbulent flow was studied experimentally. The cavitation inceptions were observed by a high speed video camera, and the velocities around the hydrofoil were measured by a 2D-LDV. It is shown that the inception cavitation bubbles are generated along with a hairpin-shaped vortex coherent structure in the boundary layer of the non-separated turbulent flow. The developing process of an inception cavitation bubble vortex comprises generation, expanding, collapse, rebound and re-collapse. It is concluded that the inception cavitation has dual characteristics of both bubbles and coherent structures.