射流冲击盖板覆盖下有限厚炸药的仿真和试验研究

Simulation and Experimental Study of Jet Impact on Covered Finite⁃thickness Explosive

为了研究有限厚炸药在射流冲击下的起爆过程,并得到有限厚炸药的临界起爆阈值。试验采用Φ40 mm聚能装药作为射流源,通过高速录像进行拍摄,对不同厚度的50SiMnVB盖板覆盖下的43 mm厚TNT炸药进行了射流冲击起爆试验,得到炸药的临界起爆阈值和不同刺激强度下的响应情况以及反应产物的膨胀速度。采用数值仿真软件进行了有限厚炸药在射流冲击下的数值模拟计算,得到了射流冲击下炸药内弯曲冲击波发展过程以及有限厚炸药的临界起爆阈值和炸药厚度关系,并通过试验结果进行了验证。最后建立了有限厚炸药临界起爆阈值和临界盖板厚度的计算模型。结果表明:厚度43 mm的TNT临界起爆阈值为37 mm3·μs^-2,并且在不同响应之间反应产物的膨胀速度相差至少一个数量级。射流冲击有限厚炸药时,弯曲波发展为爆轰波需要一定距离,剩余射流头部速度越高,弯曲波发展为爆轰波所需的距离越短。炸药厚度的减少将导致有限厚炸药的临界起爆阈值和临界盖板厚度的增加,并且有限厚炸药的临界起爆阈值的对数与炸药厚度的对数近似呈线性关系。

To study the initiation process under jet impact and obtain the critical initiation threshold of explosives with different thicknesses,experiments of jet formation withΦ40 mm shaped charge were performed and captured by the high‑speed video.The 43‑mm thick TNT explosives were covered by 50SiMnVB cover plates with different thicknesses in experiments.The critical initiation threshold,the response under different stimulus intensities and the expansion velocity of reaction products were obtained.The numerical simulation of finite‑thickness explosive under jet impact was carried out by using numerical simulation software.The propagation process of bow wave in explosive under jet impact and the relationship between critical initiation thresh‑old and the thickness of finite‑thickness explosive were analysed.The simulation results were compared and verified by the experimental data.The results show that the critical initiation threshold of TNT with a thickness of 43 mm is 37 mm3·μs^-2,and the expansion rate of reaction products varies by at least one order of magnitude between different responses.When the jet impacts on a finite‑thickness explosive,a certain distance is required for a bow shock wave evolving into a detonation wave.The higher the tip velocity of the residual jet is,the shorter the distance is required for the evolution of bow shock wave to detonation wave.Therefore,the decrease of explosive thickness will lead to the increase of critical initiation threshold of finite‑thickness explo‑sive,and the logarithm of critical initiation threshold is approximately linear with the logarithm of explosive thickness.