基于爆能等效原理大型模爆器燃气爆炸冲击加载的数值模拟

Numerical simulation on shock waves generated by explosive mixture gas from large nuclear blast load generator based on equivalent-energy principles

运用非线性显式动力有限元程序LS-DYNA,基于多物质Euler算法,对TNT炸药和乙炔-空气混合气体两种爆炸源在自由大气场中爆炸产生的冲击波荷载特征参数进行数值模拟,比较两种爆源产生的冲击波压力传播规律。基于爆能等效原理,按超压相等的原则给出了气体爆炸名义比例距离计算公式。结果表明,基于Euler算法可以较好地描述乙炔-空气混合气体爆炸空气冲击波传播规律,爆炸压力随着距爆源距离的增大而迅速衰减,且两种爆源产生的冲击波超压峰值误差随着冲击波传播距离的增大而逐渐减小。采用名义比例距离公式修正后,气体爆炸与炸药爆炸冲击波计算误差可以得到有效控制。当爆炸冲击波超压小于0.5MPa时,可以采用乙炔-空气混合气体代替化学炸药进行模爆器内爆炸实验加载。

Based on the nonlinear explicit dynamic finite element program LS-DYNA and the multi-ma- terial Euler algorithm, the shock wave propagations were numerically simulated for the two explosion resources of the TNT dynamite and the acetylene-air gaseous mixture in free air field, respectively. The overpressures of the shock waves and the propagation principles were compared between the two blast-loading methods. Based on the equivalent-explosion energy, a formula for calculating the nomi- nal scale distance of gas explosion was obtained in terms of overpressure. The results show that the Euler method can be used to calculate the propagation process of two kinds of explosion sources and the numerical results agree well with the ones based on the empirical equations. With the increasing of the propagation distances, the overpressures decrease sharply and the overpressure relative error be- tween the two load methods decreases gradually. When the shock wave overpressure was lower than 0.5 MPa, the acetylene-air gaseous mixture can replace the chemical dynamite for generating blast shock waves by the large nuclear blast load generator.