模拟雷击明火点燃松针燃料的实验研究

Experimental Study on Sustainable Flaming Ignition of Dead Pine Needles by Simulated Lightning Discharge

雷击是森林火灾重要的诱因之一,然而当前对雷击引燃森林火灾的过程和机理研究十分有限。本文通过雷击火模拟实验台产生含“长连续电流”的模拟雷击电弧,对不同含水率的松针进行了点燃实验,分析了模拟雷击电弧明火点燃松针过程中火球的产生机理和演化过程。通过图像处理获取了点燃过程中火球最大高度和0.8~1.0 s期间火柱平均高度,揭示了模拟雷击电弧能量和燃料含水率对松针点燃的影响机制:模拟电弧能量通过影响初始可燃性气体的生成量影响火球火柱热反馈行为,进而影响模拟电弧点燃松针的概率;燃料含水率通过影响“火焰自维持阶段”燃料的吸热量影响松针的点燃结果。

Lightning is one of the most important causes of wildfires, but the knowledge of the ignition process and mechanism of lightning-caused wildfires are very limited. In this work, the flaming ignition of pine needles with different moisture contents by the simulated lightning arcs with a long continuing current, which were produced by the lightning simulating equipment, was studied.The occurrence mechanism of the fire ball and its evolution during the ignition process were analyzed.The maximum height of the fire ball and the average height of the fire column within 0.8~1.0 s were obtained by the image processing method. It is found that the discharge energy and fuel moisture content can affect ignition outcome by influencing the production of the initial combustible gases and flaming self-sustaining, respectively.