不同边界条件下水下爆炸气泡的数值模拟

Numerical simulation of underwater explosion bubble with different boundaries

采用有限元程序MSC.Dytran对不同边界条件下水下爆炸气泡的脉动过程进行了数值模拟。对数值模拟中的一些重要问题,如炸药药包的建模、网格密度、状态方程和静压力场的设定等问题进行了探讨。对无限水域中的水下爆炸气泡以及自由面边界、水平刚性面边界和垂直刚性面边界三种边界条件下的水下爆炸气泡进行了数值模拟,分析了水下爆炸气泡的半径、外形变化、气泡脉动压力、流场中的速度分布,结果发现边界的存在对气泡外形的影响较大,刚性边界面会使气泡脉动压力增大较多,而自由面边界对气泡脉动压力的影响较小。将数值模拟的结果与理论模型、经验公式和试验结果进行了比较分析,结果吻合较好。

The FEM Software MSC. Dytran was used to simulate the underwater explosion bubble pulses in different boundaries. Some important problems were discussed, such as the modeling of charge, the size of element, EOS （equations of state） and hydrostatic pressure field initialization. Simulations were done on the underwater explosion bubble in infinite water, the bubble below the free surface and horizontal rigid plane and the bubble close to vertical rigid plane. The radii of bubble, the change of its figures, the pressure of bubble pulse and the velocity distributing in water were studied, and then the boundary was found to have great effect on the bubble profile, and the rigid plane could increase the pulse pressure, but the free surface not. The results of simulation of bubble pulse are proved to agree well with those of the academic formula, empirical equation and test.