Attenuation effect of a preset bubble on hydrodynamic ram induced by fragments impacting fluid-filled tank

When the fluid-filled structure is impacted by a high-velocity penetrator, the hydrodynamic ram (HRAM) will appear and may induce catastrophic damage. Based on the damage mechanism of HRAM, a countermeasure through presetting a bubble inside the fluid-filled tank is proposed to attenuate the HRAM loads and thus alleviate the vulnerability of the tank structure under the impact of high-velocity projectile. Experimental tests are performed to compare the tank’s damage considering the effect of bubble by the charge-driven preset fragments. The experimental results show that the peak pressure and impulse of the initial impact wave acting on the tank rear plate are reduced by 78% and 88%, respectively, and the cavitation collapsing pressure acting on the rear plate almost disappeared. Meanwhile, the maximum deformation of the front plate is reduced by about 15%. In addition, numerical simulation is employed to reproduce the experimental process. By comparing the structural dynamic response and the shock wave propagation process, the attenuation mechanism of the preset bubble on HRAM is revealed. Furthermore, the influence of the bubble position and size on the attenuation effect is investigated. Numerical results show that a smaller distance between the bubble and the front plate, and a larger bubble size lead to a better attenuation effect.