Numerical Study of Gas and Cavitation Bubble Dynamics in Liquid Mercury Under Negative Pressure

Gas and cavitation bubble dynamics have been studied numerically to evaluate the effect of gas bubble injection on the suppression of cavitation inception. In our previous studies it has been demonstrated by direct observation that cavitation occurs in liquid mercury when mechanical impacts are imposed and it must seriously shorten the lifetime of nuclear facilities using liquid mercury, such as the mercury spallation target of the J-PARC (Japan Proton Accelerator Research Complex). In this paper, using single-bubble and multibubble models we have performed numerical studies on the dynamics of cavitation bubbles in liquid mercury with and without preexisting gas bubbles, and have clarified that if the mercury involves gas bubbles much larger than the cavitation nuclei, cavitation inception is effectively suppressed due to the positive pressure radiated by the gas bubbles. Our recent experimental results (not shown in the present paper) have confirmed the effectiveness of the bubble injection.