Study On Bubbles Motion Characteristics Near Field Underwater Explosion Under Typical Boundary Conditions

In this paper, the method of numerical simulation was used to study on the bubbles pulsation load of underwater explosion. The motion characteristics of underwater bubble near the rigid structure and the rigid structure with a circular hole was be analyzed. On two charges explosion at the same time and time-delay, the bubbles pulsation and the load in the free field or near the rigid structure are calculated, the effect of the explosive distance on the pulsation pressure is analyzed.Firstly, the correctness of the numerical simulation method were verified by comparing with the experimental results in the literature. The damage process of underwater explosion thin plate is simulated and the results are compared with the test results. The boundary condition selection and mesh division method are determined. The accuracy of the simulation method is demonstrated.Secondly, the bubble dynamic characteristics and the effect of the different radius of the hole and the different distance were studied near the rigid structure with a circular hole based on numerical simulation in deep water. The hole changed the flow field near the bubble and influenced the bubble motion. When the hole radius is larger than the maximum bubble radius, the effects can be ignored because that the jet was not formed.Finally, the near field load characteristics were studied when the two charge were explosion at the same time in the deep water and near the rigid structure. The effect of the distance parameters x and l on shock wave superposition and motion characteristics of bubbles and jet velocity and shape were analyzed. It is showed that the shock wave load was bigger and pressure generated by second bubbles of bubbles was weaker obviously when the two charge were explosion at the same time. When the distance parameters x and l more than 2, the Bjerknes is very small and the effect of rigid structure and another bubble can be ignored.The research findings of this paper provided some valuable conclusions of engineering application in marine engineering and combat engineering field.