Comparison of spatial distribution characteristics of shock wave pressure field and cavitation bubble cloud

Abstract

This study aims to compare the spatial characteristics of the cavitation bubble cloud and shockwave pressure field. Cavitation bubble cloud images were acquired using micro pulsed light with 150us exposure time and CCD camera, and images were accumulated after repeated several acquisitions. The shockwave field was measured using an optical hydrophone to compare with the distribution of cavitation bubbles. After the shockwave device was triggered, cavitation bubbles were generated and visualized during 150us light exposure and were collapsed at the same position where they were generated. Most of the bubbles are concentrated in the focal region of the shockwave. The largest bubbles were observed at the peak negative pressure position in the focal area In the remaining focal area, it was formed as relatively small bubbles. Outside the focal area, very small bubbles were sparsely observed. Cavitation bubbles produced by a single shockwave pulse are highly correlated with the shockwave pressure at exposed location since there is no significant positional movement with time. Therefore, the distribution of cavitation bubble is similar to the spatial characteristics of the shockwave pressure field. It is possible to qualitatively analyze the shockwave pressure field by observing the cavitation bubbles which is difficult to measure.