近场水下爆炸气泡与目标尺寸匹配关系研究

Study on Matching Relationship Between Bubble and Target Size in Near-field Underwater Explosion

为了探究不同尺寸结构与气泡的相互作用机理,开展了2.5 g TNT在边长为20 cm、40 cm和70 cm固支方板底部15 cm处起爆的水下爆炸实验,通过观察实验高速录像以及传感器测得的压力数据结果得到:板的尺寸过小时,气泡在膨胀过程中会与空气接触,使得气泡脉动过程终止。为进一步探究爆炸气泡与目标尺寸的匹配关系,采用Abaqus软件中的CEL算法,固支方板以拉格朗日网格建立,其余部分以欧拉网格建立,对近场水下爆炸气泡的动力学行为以及压力数据进行数值模拟,通过将仿真结果与实验拍摄到的气泡现象与测得的压力时程曲线做对比验证了仿真方法的可行性。以爆炸深度除以最大气泡半径为比深度,以板的边长除以最大气泡半径为边长,接着开展了板边长为0.455到3.182倍最大理论气泡半径、爆距为0.455到1.136倍最大理论气泡半径的系列仿真。仿真结果表明:随着板尺寸的减小,气泡越容易提前溃散;以无量纲板尺寸和无量纲爆深为变量给出能否形成一个完成气泡脉动的分界函数;爆距与板尺寸距离分界线越近,气泡脉动结束时间越早。

In order to explore the interaction mechanism between the structure of different sizes and the bubbles,an underwater explosion experiment of 2.5 g TNT was carried out at the bottom 15cm of the fixed square plates with side lengths of 20 cm,40 cm and 70 cm.Through the observation of the experimental high-speed video and the pressure data measured by the sensor,it is found that when the size of the plate is too small,the bubble will contact with the air during the expansion process,and the bubble pulsation process will be terminated.In order to further explore the matching relationship between the explosion bubble and the target size,CEL algorithm in Abaqus software was used to establish the fixed square plate with Lagrange grid and the remaining part with Euler grid.The dynamic behavior and pressure data of the near-field underwater explosion bubble were numerically simulated.The feasibility of the simulation method is verified by comparing the simulation results with the bubble phenomenon captured in the experiment and the measured pressure time history curve.Taking the explosion depth divided by the maximum bubble radius as the specific depth and the side length of the board divided by the maximum bubble radius as the side length,a series of simulations were carried out with the side length of the board being 0.455 to 3.182 times the maximum theoretical bubble radius and the explosion distance being 0.455 to 1.136 times the maximum theoretical bubble radius.The simulation results show that with the decrease of plate size,the bubbles are more likely to collapse in advance.With dimensionless plate size and dimensionless explosion depth as variables,a boundary function is given to complete the bubble pulsation.The closer the distance between explosion distance and plate size,the earlier the end time of bubble pulsation.