关键词: 水下爆炸气泡, 刚性壁面, 气泡脉动特性, 气泡射流, 有限元模拟

Abstract: To investigate the influence mechanism of a rigid wall on the pulsation characteristics of underwater explosion bubbles, a dynamic equation for bubble pulsation near the wall is established based on the principle of energy conservation and the method of image. An analytical formula for the dimensionless pulsation period is proposed. The boundary effect law of the secondary pressure wave peak is revealed. Theoretical studies show that the pulsation period of bubbles near the wall increases with the decrease of the distance parameter, and the peak value of the secondary pressure wave on the wall can reach 1~2 times that of the free field at the same position. Through deep-water explosion experiments (200~500 m water depth) and LS-DYNA numerical simulations, the accuracy of the theoretical model is verified. Furthermore, by combining the bubble pulsation equation near the wall, an improved criterion for judging the bubble jet direction is proposed, which can accurately predict the direction of bubble jet under the failure condition of Blake criterion. This research provides theoretical support for the in-depth study of the interaction between underwater explosion bubbles and structures.

Key words: underwater explosion bubbles, rigid wall, bubble pulsation characteristics, bubble jet, finite element simulation