约束PBX炸药中心点火反应烈度演化实验研究

Experimental Study on Intensity Evolution of Central Ignition Reaction of Confined PBX Explosive

采用约束炸药中心电热丝点火实验,利用高速摄像机,拍摄了3种约束强度作用下PBX炸药点火后的微秒量级时间的反应演化过程;分析了约束强弱对最终反应烈度和反应升级特征过程的影响。结果表明,约束作用强度越大,炸药点火后能达到的反应烈度越高,且反应升级速度更快;点火后的反应演化过程大致经历了4个阶段:燃烧火焰驱动的裂纹扩展;约束界面发生对流燃烧;炸药基体断裂和破碎导致反应烈度急剧增大;约束解体。其中,在裂纹扩展及燃烧火焰传播阶段,圆环约束作用主要通过影响炸药内部应力状态进而影响裂纹扩展和燃烧反应传播的过程;在火焰达到约束界面并沿界面传播阶段,约束圆环通过变形进而引导圆环与炸药的界面发生对流燃烧;炸药基体的断裂和破碎将导致后续反应烈度进一步地快速增大。

To capture the evolution behaviors of the reaction after ignition in microsecond time scale,a high-speed camera was applied in the electrically heating wire ignition experiment with the ignition point at center of the confined explosive charge.Then the influence of constraint strength on the final reaction intensity and the characteristic process of reaction escalation was investigated.The results show that the higher intensity and the faster reaction upgrading speed can be achieved as the restraint intensity increases.The reaction evolution process after ignition has roughly experienced four stages:crack propagation is driven by combustion flame;convective combustion occurs at the confined interface;fracture and fragmentation of explosive matrix lead to the sharp increase of reaction intensity;reaction extinction due to pressure relief.By influencing the internal stress state of the explosive at the crack extension and combustion flame propagation stages,the ring restraint influences the crack expansion and combustion flame proliferation.In addition,as the flame propagates along the ring interface,the ring restraint deforms,forcing the combustion flame into the interface between the ring and the explosive.Fracture and fragmentation of the explosive matrix will further escalate the intensity of the subsequent reaction.