The Structure of Tip Vortices Over a Range of Cavitation Number

The tip vortex roll-up process from an elliptic wing was experimentally investigated. Cavitation provided an excellent method for visualizing the mechanism of vortex roll-up. The velocity profiles of the non-cavitating vortex were first obtained with a laser Doppler velocimeter. The measured asymmetry of the velocity profile and the computed pressure distribution in the vortex core are discussed. In the case of fully developed cavitation, the vortex trajectory was analyzed and compared with theory. The cavity core radius increased with reduced pressure until the developed cavity forms a twisted ribbon structure. The core thickness and the wave length of these structures are also discussed.