炸药爆炸抛撒典型灭火介质特性及其灭火机理研究

Compared with the traditional ways of fire-extinguishing, explosion method is an efficient and quick manner which can be used to extinguish the fire at forests or grasslands. It has the unique advantage over the other ways, especially for the small-area fire or inapproachable fire site(e.g.under the condition of toxic or radiative). Water and fire-extinguishing powder are the common mediums used by the fire-extinguishing bombs. The present technologies for fire-extinguishing bombs usually limit to the study of their practical use. The fire-extinguishing mechanism and its effectiveness were paid not enough attention. So the study on the fire-extinguishing mechanism and its effectiveness for water or powery fire-extinguishing agent impelled by explosion has important theoretical and practical significance. The project firstly considered the movement rules of water and fire-extinguishing powder impelled by chemical explosion. The high-speed video camera was adopted to observe the whole process of water-mist or dispersed powder impacting on fire. According to the camera photos, approximately calculated the parameters for the dispersed mediums including particle velocity and dispersed radius, which can quantitatively analyse the situation of mediums dispersing. Considering the influence factors including charge of explosive, mass of water or powder and distance between the center of explosion and fire,and so on, the Orthogonal Experiment was design to find the best fire-extinguishing effect. The PVDF piezoelectric sensors and rapid-response thermocouples were used to acquire the pressure and temperature variation at the position near fire in the process of fire-extinguishing, respectively. And combined with the high-speed camera photos of the dispersed mediums impacting on fire,the fire-extinguishing mechanism and its effectiveness for water or fire-extinguishing powder impelled by explosion were studied comprehensively, and, its multipase flow coupling model "shock wave-fire extinguishing agent-fire" was presented.

相对于传统灭火方式而言，爆炸抛撒水和粉体灭火介质具有高效、灵活、快捷等优点，可使用在森林、草原等火灾扑救，尤其对于过火面积小、人员无法接近的特殊火场(如有毒、有辐射环境等)，具有独特的灭火优势。现有的水和灭火粉体介质构成的爆炸灭火弹技术研究主要偏重于实际应用，在介质灭火机理及有效性方面研究得较少。因此研究水和粉体灭火介质爆炸抛撒灭火机理及有效性对防灾减灾具有重要理论和实际意义。本项目采用高速摄像技术研究灭火介质在爆炸作用下的抛撒特性，采用正交试验法研究炸药质量、灭火介质质量、距离、火场燃烧特征等因素耦合效应对灭火效果的影响，采用DPIV技术分析爆炸水雾粒度分布，采用高速显微技术观测灭火粉体介质与火焰作用过程，采用PVDF压电计和热电偶技术测量灭火弹作用的压力场和温度场，研究水介质和粉体介质的灭火机理，构建相应的“激波-灭火介质-火源”多相流耦合模型，提出灭火的有效性表征与判断。

爆炸法灭火技术具有高效、灵活、快捷等优点，在一些特殊环境下（如有毒、有辐射环境等）发挥独特的灭火优势。研究爆炸驱动水、干粉、干水材料等典型介质灭火机理及有效性对防火防爆具有重要理论和实际意义。本课题采用高速摄像、微细热电偶测温、PVDF测压等测试手段，研究了炸药爆炸直接灭火、爆炸水雾灭火、爆炸驱动干粉和干水材料灭火过程，初步分析了几种情况下爆炸灭火的有效性和灭火机理问题，主要内容和结论如下：.(1) 探究了炸药爆炸直接灭火机理、爆炸水雾、爆炸驱动干粉和干水材料灭火机理问题，为优化水基和粉体基爆炸灭火弹设计提供重要技术支撑。.(2) 开展了炸药爆炸直接引燃和灭火效应的实验。结果表明：炸药爆炸兼有引燃效应和灭火效应；因单体猛炸药爆炸后产生的爆温高，在产物和激波共同作用下可能会引燃汽油等易燃品，而工业炸药相比单质猛炸药引燃汽油等易燃品的概率相对较低，其爆炸后起主导作用的是灭火效应；同时，炸药爆炸易引燃瓦斯等可燃性气体。.(3) 通过正交试验法测试分析了爆炸水雾灭火与爆炸驱动干粉灭火影响因素。结果表明：爆炸水雾对火的作用来源于冲击波和爆炸水雾两方面，强冲击波对燃烧有抑制作用，弱冲击波对燃烧有促进作用。干粉质量越大，距离火源中心越近，与火源中心之间的夹角越小，则爆炸抛撒粉体灭火效果越好。.(4) 对比分析了爆炸驱动下干粉灭火剂和水运动特性及灭火效果。结果表明：爆炸装置直径、介质质量对两类介质爆炸抛撒过程、抛撒半径、抛撒作用时间有着显著影响；等体积的干粉和水进行爆炸灭火，水介质到达着火区域较快，而干粉驻留时间较长。.(5) 优选制备出一种新型干水灭火材料，采用高速摄像观测爆炸驱动干水材料和干粉扑灭柴油火过程。结果表明：相同条件下，爆炸驱动干水材料灭火效率较干粉灭火剂高，干水材料灭火过程兼有物理降温和化学抑制联合灭火机制。