铝热剂反应性冲击热点分析

 采用激光粒度扫描仪测量了二元混合物铝热剂（Al+Fe₂O₃）原料的粒径分布，在电子显微镜下观察了铝颗粒、氧化铁颗粒的颗粒形状及两者按照化学配比混合后的颗粒接触状态。综合粒径分布和反应体系的化学配比关系，得到两种反应物的特征粒径和混合物的颗粒布局。根据特征粒径和颗粒布局，建立了该反应体系的等效细观模型，该细观模型能够保证得到与实际颗粒体系相一致的具有统计意义的孔穴结构。采用无网格粒子方法，数值模拟了铝热剂体系在不同冲击速度作用下，基本氧化铁颗粒排列形成的热点特征。研究表明，氧化铁三颗粒紧密排列的模式为形成单独热点的最基本排列，在平面冲击作用下，二元不同粒径的含能材料混合物形成热点的尺寸由初始孔穴尺寸确定，而热点温度受冲击速度影响较大。采用轻气炮对不同密度和配比的铝热剂进行了冲击点火实验，并将测量和数值计算结果进行了对比分析，结果表明，两者的定性结论吻合较好。

Analysis of Reactive Hot Spot for Thermite under Shock Waves

Using laser scaners to measure the size of binary mixture of energetic materials thermite (Al+Fe₂O₃) and get the particle size distribution, the particle shape of aluminum powder, iron oxide and the contact status of the mixtures meeting the standard chemical proportion are observed under the electron microscope. Combined the raw material particle size distribution and the mass ratio of chemical reaction, the particle characteristic size (equivalent volume radius) and arrangement of aluminum and iron oxide particle were obtained. Based on the above conditions, the mesoscopic model for the thermite mixtures was established. The mesoscopic model can be guaranteed to get the statistical cavities structure consistent with that of the actual granular system. The features of "hot spot" for the thermite by impact were studied with the Smoothed Particle Hydrodynamics (SPH) method, under the condition of different particle arrangements and shock velocities. The result shows that the arrangement  of three iron oxide particles closely contact each other is the basic one forming a single "hot spot"; the size of hot spot is determined by the initial size of the cavity; and the temperature of "hot spot" is controlled by the shock velocity. Finally, the thermite mixtures of different density and chemical ratio were impacted on the light gas gun, the qualitative regularities of experiments are well consistent with those of numerical simulation.