Ignition and burning mechanisms of RDX/HMX particlessubjected to drop-weight impact
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摘要: 对单质炸药受低速撞击的力学和化学响应研究，是进行炸药敏感性评价的基础。利用配备了光学观测的落锤撞击装置，实现了频率为1.5×105 s-1的实时观测，不但可以区分样品的“爆”或“不爆”，而且可以获取RDX和HMX颗粒炸药受落锤低速撞击变形、破碎、溅射、点火和燃烧随时间演化的特征。结果表明:RDX颗粒是在液相中点火，而HMX颗粒在固相中点火; 燃烧反应前常常发生剧烈的溅射现象，溅射是由气相反应产物释放能量推动破碎的颗粒所致。对比了单个和单层颗粒炸药响应的特点，多个颗粒由于热点密集和破碎后相互作用，其燃烧反应比单个颗粒燃烧反应更剧烈。根据图像处理估算燃烧波传播速度，很好地表征了样品宏观燃烧反应的剧烈程度。Abstract: The mechanical and chemical response of explosives under low velocity impact is the basis for the evaluation of their sensitivity. The drop-weight impact apparatus equipped with the optical photography was used to achieve a frequency of 150 thousand seconds of real time observation. It was capable of distinguishing the samples of "Go" or "no Go" and observing such characteristics of deformation, crushing and breakage, jetting, ignition and combustion evolution, of RDX and HMX particles under low velocity impact. The selected photographic frames show that ignition occurred in the partially melted RDX phase. But for the HMX particles, ignition mainly occurred in the solid phase. A violent jetting phenomenon often occurs before the reaction of combustion. The occurrence of jetting primarily results from the energy released by gaseous products, which push the pulverized or melted explosives splash. The response characteristics of single and multiple granular explosives were compared. Because of the interaction of the hot spots broken, the combustion reaction of the particles is more intense than that of the single particles. The size ratio of the image to the actual length can be used to estimate combustion wave propagation velocity in each case, which is very suitable for characterizing the intensity of the macro-combustion reaction.
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Key words:
- combustion /
- drop-weight impact /
- RDX/HMX /
- granular explosives /
- ignition /
- high-speed photography
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图 1 扫描电镜观测的不同放大倍数下的RDX和HMX颗粒样品
Figure 1. Microscopic morphologies of RDX and HMX particles observed by scanning electron microscopy
图 2 落锤加载装置及光路观测示意图
Figure 2. Schematic diagram showing the drop-weight loadingand optical measurement system
图 4 单个RDX颗粒受撞击的响应过程，落锤下落高度为15 cm
Figure 4. elected photographic frames for an individual RDX particlein response to a drop-weight impact with 15 cm height
图 6 单层(10颗)RDX颗粒受撞击后的点火燃烧图像，落锤下落高度为15 cm
Figure 6. Selected photographic frames for ten RDX particles in response to a drop-weight impact of 15 cm height
图 8 单个HMX颗粒受撞击的响应过程，落锤下落高度为15 cm
Figure 8. Selected photographic frames for an individual HMX particle in response to a drop-weight impact with 15 cm
图 10 单层(10颗)HMX颗粒受撞击后的点火燃烧图像，落锤下落高度为15 cm
Figure 10. Selected photographic frames for ten HMX particles in response to a drop-weight impact with 15 cm
表 1 火焰传播速度
Table 1. Propagation velocity of combustion flame
实验方案 落锤高度/cm 火焰速度/(m·s-1) 单个RDX颗粒 15 173.9 单层多个RDX颗粒 15 235.4 单个HMX颗粒 15 93.0 单层多个HMX颗粒 15 308.9 
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