A Study of Bubble Dynamics on the Dielectric Recovery Underwater Discharge

This study numerically investigates the dielectric recovery characteristics of underwater pulsed discharge by coupling the Keller–Miksis equation with interfacial phase-change mass transfer. The model incorporates the time-varying internal pressure and temperature of the bubble, enabling accurate prediction of the second breakdown voltage during both the gradual expansion–contraction stage and the initial collapse stage. Three representative values of the phase-change mass transfer coefficient αM are examined to quantify its influence on bubble pulsation and dielectric performance. Results indicate that αM exerts a distinct differential effect: while the first pulsation is governed primarily by liquid inertia and remains insensitive to αM, the energy dissipation during the first collapse is critically regulated by interfacial condensation. High αM intensifies condensation, removing vapor mass and latent heat, thereby reducing residual energy for subsequent pulsations and accelerating pulsation decay. These cumulative attenuation effects shorten the dielectric recovery time. The calculated recovery voltages show good agreement with experimental measurements, confirming the validity of the proposed model for predicting dielectric recovery in repetitive underwater pulsed discharge systems.