不同真空度下空中爆炸近场特性的数值模拟研究

Numerical simulation for near-field characteristics of air explosion under different degrees of vacuum

外界环境的改变会使空中爆炸时冲击波的传播过程产生明显变化,为分析真空度对爆炸近场特性的影响,建立了自由场空中爆炸的有限元模型,在萨克斯比例定律的基础上,通过引入特征比例距离Z,分析了不同真空度下爆炸近场特征参量的变化规律。分析结果表明:以霍普金森比例距离和特征比例距离Z为变量的分段函数可表述不同真空度全范围内的爆炸峰压Δp_m;比冲量i和正压作用时间t+的变化具有非单调性,且与爆轰产物稀疏波尾部的间断面密切相关;不同真空度下的爆轰产物界面和冲击波阵面时程曲线在无量纲坐标系中分别重叠,而极限膨胀体积与临界距离R_s呈线性关系。

External environment variation makes shock wave propagation of air explosion produce obvious changes.In order to analyze the influence of degree of vacuum on near-field characteristics of air explosion,the finite element model of a free-field air explosion was established.Based on Sachs scaling law,introducing the characteristic scaled distance Z,the variation laws of explosion near-field characteristic parameters under various vacuum degrees were analyzed.Results indicated that the piecewise function taking Hopkinson scaled distance and the characteristic scaled distance Z as variables can express the explosion peak pressureΔp m within the full range of different degrees of vacuum;the variation of specific impulse i and positive pressure action time t+is non-monotonic and closely related to sparse wave tail discontinuity surface of detonation product;time history curves of detonation product’s interface and shock wave front under different degrees of vacuum are overlapped,respectively in a dimensionless coordinate system,and the ultimate expansion volume is linearly related to critical distance Rs.