Cavitation in co-rotating tip vortices

This work documents flow characterization and cavitation inception of a co-rotating vortex pair shed from a single fin with a rounded tip at zero angle of attack. The fin was outfitted with a removable tip fabricated using a rapid prototype method. The co-rotating vortices result from surface discontinuities on the removable tip, near a hard wax fairing used to cover the tip attachment bolt. The vortices are shed at different locations along the chord. Flow visualization by oil paint and developed cavitation, and SPIV of the near-wake, indicate that a strong vortex is shed at the trailing edge, while a weaker vortex is shed at 82% chord. Horizontal wandering of the vortices is uncorrelated. Vertical wandering of the vortices is characterized by opposing oscillations about their mutual center. Acoustic cavitation inception in the water tunnel environment is discerned at an index 13% greater than visual detection of cavitation, and occurs within one chord of the trailing edge. The influence of the co-rotating vortex system on cavitation inception must be determined from comparison with measurements of a solitary vortex generated by analogous geometry.