Equilibrium of ventilated cavities in tip vortices

The behavior of air cavities formed in the tip vortex trailing from rectangular and elliptical planform hydrofoils has been examined both theoretically and experimentally. These cavities have some peculiarities, in particular their ability to move upstream and reach a stable position near the hydrofoil. Detailed measurements of the the velocity components and the cavity characteristics have been made. The results are compared with the predictions of a theoretical model based on the equilibrium balance of a cavity developing in a Lamb vortex.