小当量梯恩梯水下爆炸气泡脉动的数值模拟

Numerical Simulation of Bubble Pulsation of Small-scaled TNT in Underwater Explosion

为了更准确地模拟小当量梯恩梯(TNT)水下爆炸的气泡脉动过程,对气泡脉动数值模拟结果的影响因素进行探究。应用Autodyn有限元软件对13 g TNT水下爆炸进行数值模拟发现,使用TNT的JWL状态方程和水的多项式状态方程及其参数,且网格尺寸为5 mm、边界条件为压力流出时,数值模拟结果与经验公式计算得到的理论值间误差较小。改变网格尺寸和边界条件,发现在满足工程精度前提下,网格尺寸为1 mm且边界条件为压力流出时数值模拟结果较准确,其中气泡脉动周期以及气泡膨胀最大半径的数值模拟结果与经验公式间的误差仅为3.61%和1%.对10 g TNT开展水下爆炸试验,并基于以上条件对试验进行数值模拟。发现各测点处试验结果与数值模拟结果间的误差较小,进一步验证了气泡脉动数值模拟的真实性和准确性。对10 g TNT炸药在不同爆炸深度下的气泡脉动进行数值模拟,得到了气泡脉动周期T和气泡膨胀最大半径Amax与爆炸深度H之间的关系:T=23.2e^(-H/92.93)+39.76e^(-H/12.74)+2.08,Amax=0.12e^(-H/324.67)+0.16e^(-H/14.85)+0.07.

The factors influencing the numerically simulated results of bubble pulsation are analyzed to accurately simulate the underwater explosions bubble pulsation of small-scaled equivalent TNT.The underwater explosion of 13 g TNT was numerically simulated by Autodyn.The results show that the error between the numerically simulated results and the calculaet results of empirical formulas is smaller while the grid size is 5 mm and the boundary condition is Flow_out.The numerically simulated results of underwater explosion bubble pulsation of small-scaled equivalent TNT are more accurate when the grid size is 1 mm and the boundary condition is Flow_out,where the error between the calculated and simulated bubble pulsation periods is 3.61%,and the error between the calculated and simulated maximum radii of bubble expansion is 1%.An underwater explosion experiment of 10 g TNT was carried out,and the experiment was numerically simulated by using the above conditions.It is found that the error between the experimental and simulated results at each measuring point is small,which further verifies the accuracy of numerical simulation of bubble pulsation.At last,the bubble pulsation of 10 g TNT at different explosion depths is numerically simulated,and the relationships between the bubble pulsation period with the explosion depth,and the maximum radius of bubble expansion with the explosion depth are obtained.