Mechanism of impact pressure generation from spark-generated bubble collapse near a wall

Abstract

This paper deals with a detailed experimental investigation on the collapse of a single spark-generated bubble near a solid wall and the mechanism of its induced impact pressure generation. By changing L//?max from 0.14 to 17.1, where L is the distance between the electrodes and the solid wall and /?max a maximum bubble radius, the collapse of the bubble was observed with an Ima-Con high speed camera and, simultaneously, the induced impact wall pressure was measured. Consequently, the induced impact wall pressure history revealed that three types of the bubble collapse modes exist depending on L//?max; i.e., the region where a shock wave is dominant to the impact wall pressure at L//?max 1.5, a liquid jet at 0.6 <L//?max <0.8, and both a shock wave and a liquid jet at 0.3 < L//?max ^ 0.6 and 0.8 < L//?max < 1.5.