Cavitation damage reduction by microbubble injection

A series of experiments on cavitation caused by mechanically induced pressure pulses have been performed to provide experimental evidence that gas microbubbles injected into a liquid can reduce cavitation damage. The working fluid of the present study is liquid mercury as in spallation neutron sources to produce high-intensity neutron beams, and the experiments were conducted under three different flow conditions: single-phase static, single-phase flow, and bubbly flow conditions. The experiments suggested that compared to the static case, cavitation damage is reduced by flowing the mercury, and further remarkably reduced by injecting microbubbles into the mercury flow. A slight decrease in the magnitude of negative pressure found in the bubbly flow case appears to be a key to understanding the mechanism of the observed cavitation damage reduction.