非理想炸药水中爆炸载荷相似律数值仿真

Numerical Simulation of Similarity Law of Underwater Explosion Load Produced by Non-ideal Explosives

为研究不同尺度非理想炸药水中爆炸载荷的相似性,采用LS-DYNA软件的S-ALE算法,构建了基于JWL-Miller状态方程描述的非理想炸药水中爆炸载荷数值计算模型;利用典型试验数据对计算模型参数进行了标定,匹配设置了典型RDX基非理想炸药的JWL-Miller状态方程参数;通过不同尺度炸药在不同水域环境条件下的爆炸过程模拟,分析了爆炸载荷特征参数的相似性。结果表明,影响非理想炸药水中爆炸冲击波压力峰值相似律的主要因素是其自身的非理想特性;水域环境因素(如自由面及静水压力梯度等)会对气泡脉动周期与半径的相似律产生较大影响。对于15%允许误差范围的工程仿真而言,0.53~5.30 m/kg 1/3比例距离(约10~100倍炸药半径)范围内,非理想炸药自由场水中爆炸载荷参数相似律可近似满足,与理想炸药的相似律特征基本一致,工程可用。基于JWL-Miller状态方程统一参数描述的非理想炸药默认其后燃反应是稳定且完全的。在实际中,由于水下非理想炸药受到复杂的化学反应动力学的控制,几何尺寸效应仍有可能导致非理想成分释能过程的较大差异,因此,精细化数值仿真需要针对不同比例距离或不同尺度模型来匹配不同的Miller模型参数,爆炸载荷相似律也可能在更有限的尺度范围内成立。

To study on the similarity law of underwater explosion load produced by non-ideal explosives,the computing models of underwater explosion load produced by non-ideal explosives with JWL-Miller equation of state were built based on S-ALE algorithm of LS-DYNA software.The parameters of computing models were calibrated and the JWL-Miller model parameters of non-ideal RDX-based explosive were matched through the experimental results.The similarity of explosion load parameters was analyzed by simulation of explosion process produced by explosives with different sizes under different water environmental conditions.The results show that the main reason that affects the similarity law of the pressure peak value of blast wave parameters is the non-ideal characteristic of the explosive.Water environment factors such as free surface and hydrostatic pressure gradient have great influence on the similarity law of bubble period and radius.For the engineering simulation with 15%allowable error,the similarity law of non-ideal explosive free field underwater explosion load parameters can be approximately satisfied in the range of 0.53-5.30 m/kg 1/3 scale distance(about 10-100 times the explosive radius),which is basically consistent with the similarity law characteristics of ideal explosive,and can be used in engineering.Based on the unified parameter description of JWL-Miller equation of state,the afterburn of non-ideal explosives is stable and complete by default.In practice,because underwater non-ideal explosives are controlled by complex chemical reaction dynamics,the geometric size effect may still lead to large differences in the energy release process of non-ideal components.Therefore,the refined numerical calculation needs to match different Miller model parameters for different scale distances or different scale models,and the similarity law of explosion load may also be established in a more limited scale range.