Analysis of underwater shock wave attenuation by air bubble curtain based on bubble shape

Abstract

Bubble curtain is an important means to protect underwater explosion shock wave. It is of great significance to study the mechanism and technical parameters of bubble curtain for safety and application of underwater blasting. By using high-speed photography technology and video framing processing technology, indoor small underwater bubble curtain model is photographed and analyzed. It is found that the gas curtain is highly discontinuous and inhomogeneous in both the formation process and the interaction process with the underwater explosion shock wave. The gas and liquid are mixed in the air curtain area, and the interface contour is complex and diverse. Air displacement will directly affect the quality of the air bubble curtain. The larger the air displacement, the better the continuity and quality of air curtain. On this basis, consider the influence of bubble shape, interface, and gas-liquid coexistence , programming is carried out through the APDL language that comes with the LS-Dyna finite element software. By setting the variation range of bubble diameter and the minimum difference between bubble diameters, a certain number of bubbles of different diameters are randomly placed to simulate the distribution of bubbles in the real air curtain. The air curtain quality under different gas source pressure can be simulated by changing the number of bubbles in the set air curtain area. It is found that this method can more truly reflect the protection mechanism of air curtain in the protection process of shock wave. Comparing the protective effect of air curtain with different bubble numbers on the same shock wave, it shows that with the increase of bubble number in unit area, the protective effect is more obvious. However, when the number of bubbles reaches a certain number, the overall continuity and stability of the air curtain are basically fixed, and the protection effect tends to be stable.