Experimental and numerical simulation investigation of cavitation phenomenon during bubble pulsation process

The current research on the cavitation phenomenon in the underwater explosion process is focused on the shock wave phase. In this study, it was found that there was also significant cavitation during bubble pulsation. Underwater explosion experiments were carried out at the bottom of a sheet using 2.5 g of TNT, which also showed that: (a) Cavitation lasts for the same duration as the bubble contraction time, (b) A cavitation closure pressure, the peak of which is greater than the bubble pulsation pressure, is produced by the closing of the cavitation zone. A tensile cut-off model was introduced to simulate the cavitation phenomenon during bubble pulsation, and the formation mechanism was investigated. The numerical simulation results show that: (a) The cavitation phenomenon is visible when the sheet above the explosive and the explosion distance are between 0.93 and 1.17 times the radius of the largest bubble, or between 0.69 and 1.85 times the maximum radius of the bubble when the sheet below the explosive, (b) The cavitation region and cavitation closure pressure increase and decrease with increasing explosion distance, peaking at a value close to one times the theoretical maximum bubble radius, and (c) The cavitation zone shrinks and the cavitation closing pressure drops as sheet thickness increases.