Rough Surface Effects on Cavitation Inception

Abstract

Cavitation inception and the associated bubble dynamics in turbulent boundary layers adjacent to surfaces roughened with triangular grooves is investigated in a two-dimensional recirculating water tunnel. The experiments result in the significant conclusion that the cavitation inception index is directly related to the skin friction coefficient for both smooth and rough boundaries. Cavitation is observed to occur away from the wall approximately in the center of the boundary layer, and is apparently the result of negative peaks in static pressure having a magnitude which exceeds 5 times the expected value of root mean square wall pressure. Mean velocity and skin friction data are correlated with existing theory for equilibrium boundary layers.