局部高温诱发CL-20/TNT共晶炸药内反应流传播的ReaxFF分子动力学模拟

为了更好地理解含能材料热点火以及热点成长现象和机理,采用基于第一性原理的Reax FF反应力场分子动力学方法模拟了CL-20/TNT共晶炸药内反应流传播的时空行为和初始化学反应过程。通过NVT系统和Berendsen温度耦合方法对含能材料两端连续快速加热并维持在高温条件激发反应流的产生和传播,并采用两种不同的热载荷(3000,4000 K)比较温度差异对初始热分解速率的影响。两端热载荷为4000 K时,热冲击传播过程中粒子瞬时平动速率可达0.5 km·s~(-1),高于3000 K时的情况。于此同时,两端高温将引发含能材料逐渐发生分解反应,同温度条件下,共晶中CL-20的分解速率高于TNT。另外,热载荷温度越高,共晶完全分解所需的时间越少。产物识别分析显示,CL-20/TNT共晶热分解的主要产物为NO_2,NO,H_2O,N_2,CO,CO_2,HONO,H_2O_2,CHON,H_2N,CH_2O,其中,NO_2是初始热分解产物,而最终产物为N_2,CO_2和H_2O。

Reactive Flow Propagation in CL-20/TNT Co-crystal Explosive Induced by Local High Temperature Zones: ReaxFF Molecular Dynamics Simulations

In order to understand the phenomenon and mechanism of thermal ignition and hot spots growth in energetic materials, spatiotemporal behaviors of thermal shock propagation in CL-20/TNT co-crystal and initial chemical reaction process were studied by first principles based ReaxFF reactive force field molecular dynamics simulations. Thermal shock mechanical wave induced by continuous fast heating of two ends in energetic materials and keeping it at high temperatures combining NVT ensemble and Berendsen temperature coupling method. In addition, two kinds of high temperature conditions (3000,4000 K) were set up to study the influence of temperature difference on the initial thermal decomposition rate. When thermal loading is 4000 K, particle instantaneous translation rate can reach 0.5 km·s^-1 in early thermal shock propagation process, higher than the situation of 3000 K. At the same time, high temperature will lead co-crystal energetic materials decomposition. Here, molecule recognition algorithm is used to analyze the initial products and species. The decomposition rate of CL-20 is higher than that of TNT in the thermal shock propagation process under two kinds of thermal loading. The higher temperature of the thermal loading, the less time required to completely decompose. Product identification analysis shows that the main products of CL-20/TNT thermal decomposition are NO₂, NO, H₂O, N₂, CO, CO₂, HONO, H₂O₂, CHON, H₂N, CH₂O, where, NO₂ is the early initial thermal decomposition product, N₂, CO₂ and H₂O are the final products.