Cavitation Bubble Collapse Observations in a Venturi

Abstract

Bubbles collapsing in water in a cavitating venturi are photographically observed. The large pressure gradient in the venturi causes the bubbles to collapse by flattening in the direction of flow. In many cases a torus is formed, implying the existence of a central jet which, as has been suggested by other investigators, may well be the primary damaging mechanism in cavitating flows. The effect of adjacent bubbles upon each other is visually observed. Numerous bubble rebounds, even in relatively degassed water, are noted. A comparison of observed collapse rates with incompressible theory for a spherical bubble indicates that the slowing down of collapse herein observed at small bubble radii probably results primarily from the asymmetry of the collapse and perhaps also from metastable compression of vapor within the bubble.