Study on cavitation scale effects especially with respect to cavitation-induced high-pressure pulses

As a first step to clarifying the mechanism of scale effects on cavitation erosion, cavitation-induced shock pressure pulses were carefully investigated around four similar flat hydrofoils, from 53 mm to 160 mm in a chord length C, under a so-called 'true similar conditions' of the same flow velocity, incidence and cavitation number as well as almost the same nuclei distribution in the test water, within the subcavitation region. Under these similar conditions no marked scale effects on the mean pressure are recongnized. When C is large, very large U-shaped vortex cavitation bubbles grow and predominantly collapse, resulting in very high locally concentrated pressure pulses on the foil surface. On the other hand, a large number of moderate pressure pulses attack the surface in a smaller C.