Experimental and numerical study on bubble pulsation characteristics of underwater explosions with multiple charges

This study examines the processes of expansion, merging, and collapse of multiple underwater explosion bubbles through experimental and numerical methods. A small-scale underwater explosion experiment was conducted in a water tank. The behaviors of three and four bubbles during expansion, merging, and collapse were captured using high-speed photography, and the effects of the quantity and spacing of the explosive charge on the bubble dynamics were analyzed. The results indicate that the evolution of bubble behavior in multiple charge underwater explosions, including the bubble period and radius, is significantly influenced by the spacing between charges. With a decrease in the ratio of the charge spacing to the bubble radius, the period of the merged bubble increases progressively. Independent small bubbles do not interact when the distance between charges exceeds 1.3 times the bubble radius. Furthermore, when the ratio of the spacing to the initial bubble radius (L/r(b)) is between 1.0 and 1.3, multiple bubbles merge during the contraction phase. When the spacing is less than the maximum radius of the bubbles, multiple bubbles inevitably merge, with fusion occurring during the expansion phase.