Bubble evolution mechanism of pulse spark discharge in seawater

Underwater spark discharge could generate high-pressured bubble oscillations, which has broad application prospects in marine acoustic exploration and medical therapy. Much research has been focused on the first oscillation period, while little attention has been paid to the following periods and discharge efficiency. In this work, we studied the bubble evolution characteristics of three oscillations, as well as the multi-factor effects on radius, oscillation periods and energy efficiency. An experimental method is presented to control several influential factors to analyse their influences on bubble evolution and energy transformation. Notably, an image process algorithm is proposed to accurately describe the bubble evolution and the energy transformation efficiency. In addition, we analysed the jet flow formation during the first bubble growth and the non-uniformly distributed bubble dispersion. These results could provide references to the future optimization of bubble dynamic models and design of controllable acoustic sources.