Cavitation Inception During Vortex-Vortex Interactions of Counter Rotating Vortex Pairs

In many hydrodynamic turbulent shear flows, the weaker, stream-wise oriented vortices will cavitate before the stronger, span-wise vortices. This occurs due to stretching of the weaker vortices by the stronger vortices, which leads to a reduction in the core pressures of the weaker vortices. The stretching leads to reduced vortex core diameters and axial flow, but the relative interplay of these is still unclear. This study experimentally examines a canonical case of this vortex interaction and inception process by looking at a pair of initially parallel line vortices undergoing the Crow instability. The vortices are generated by hydrofoils whose relative arrangement can be adjusted to vary the flow properties. Measurements with high-speed Shake-the-Box PTV, high speed video, and hydrophone acoustics are taken to characterize the flow development and relate the inception properties to the underlying single phase vortex interaction. The resulting cavitation inception pressure and event rates are then related to both the flow dynamics and the freestream nuclei content.

This work was supported by Office of Naval Research, under program managers Dr. Ki-Han Kim and Dr. Julie Young, MURI Grant Number N00014-17-1-2676.