Modeling Bubble Motions by Underwater Explosion in a Centrifuge

Abstract

Bubble oscillations generated by underwater explosions (UNDEX) can cause considerable damage to nearby marine vehicles or hydraulic structures as the energy inside the bubble is comparable to that of a shock wave. Since both compressibility and gravity affect the bubble impulse, it is not easy to reproduce the pulse pressure by experiments in vacuum tanks or pressurized tanks. This study presents the promising prospect of using a centrifuge to model bubble motion. Primarily, the influence of gravitational acceleration on bubble oscillation and migration is studied. Hypergravity is not only a necessary condition to satisfy the similarity of the Mach and Froude numbers but can also reduce the boundary effects and corresponding errors when modeling a bubble in a confined container. The scaling laws derived from the physical processes of bubble dynamics and the similarities in bubble shapes and migration are validated. Moreover, the main sources of possible errors for an UNDEX in a centrifuge are discussed to show the reliability of the results followed by suggestions for reducing the error in the physical modeling of an UNDEX event.