水成膜泡沫剂对液滴冷却高温金属表面的影响  

Effect of Aqueous Film-Forming Foaming agent on liquid drops cooling on high-temperature metal surface

作　　者：吴刘锁 刘美麟 张美琪 张建成 王志刚 景伟 朱小龙 WU Liusuo;LIU Meilin;ZHANG Meiqi;ZHANG Jiancheng;WANG Zhigang;JING Wei;ZHU Xiaolong(State Grid Electric Power Research Institute Co.,Ltd.,Nanjing 211106,China;State Key Laboratory of Fire Science,University of Science and Technology of China,Hefei 230022,China)

机构地区：[1]国网电力科学研究院有限公司,南京211106 [2]中国科学技术大学火灾科学国家重点实验室,合肥230022

出　　处：《安全与环境学报》2023年第6期1880-1888,共9页Journal of Safety and Environment

基　　金：国家重点研发计划项目(2018YFC0809502);国家自然科学基金项目(51874265)。

摘　　要：向细水雾中添加水成膜泡沫灭火剂成分能明显提升针对B类火灾的灭火效果,但添加剂能否提升水雾对火灾区域内固体表面的冷却效果尚不清楚。分别从金属表面温度、We数和是否添加泡沫灭火剂3个方面设置了试验条件,开展了单液滴撞击高温金属表面模拟试验并对冷却效果进行了定量计算。结果表明,液滴的最大铺展因子与撞击动量正相关,含添加剂液滴表面张力降低且流变特性呈现剪切变稀特征。当Leidenfrost现象发生时,碰撞试验表明泡沫溶液液滴相较于纯水液滴的最大铺展系数更小且回弹速率更大,因此泡沫灭火剂的添加不利于提升吸热效率。研究结果可为泡沫细水雾技术的灭火实践提供理论指导。Adding Aqueous Film-Forming Foam(AFFF)extinguishing agent into water mist can obviously enhance the extinguishing effect on B-type fire.However,it is not clear whether AFFF can enhance the cooling effect of water mist on the solid surface in the fire area.In this paper,the experimental conditions were set from three aspects:metal surface temperature,We number and whether to add foam extinguishing agent.The simulation experiment of a single droplet impacting on a high-temperature metal surface was conducted,and the cooling effect of the single droplet was quantitatively calculated.The experimental results show that the maximum spreading factor of droplets increases with increasing impact momentum.With the addition of AFFF fire extinguishing agents,the surface tension of the droplet decreases,and the rheological property shows shear thinning,which results in the maximum spreading coefficient of the foam droplet below the pure water droplet when the impact momentum is relatively large.When the metal surface temperature is lower than the Leidenfrost point,the droplet will absorb heat and evaporate completely on the metal surface after impacting and spreading on it.Due to the small surface tension and the large viscosity of droplets with the addition of foam extinguishing agents,the droplet diameter reversion rate during evaporation is obviously lower than that of pure water droplets.Therefore,the addition of a foam extinguishing agent can improve the efficiency of heat absorption.When the metal surface temperature is higher than the Leidenfrost point,the droplet will break and rebound respectively after spreading,and the spreading and heat absorption time on the metal surface does not exceed 8 ms.Therefore,the heat absorption of a single droplet impact is only 0.005%0.03%of the heat absorption when it evaporates completely.When the Leidenfrost phenomenon occurs,the impact test shows that the maximum spreading factor of the foam droplet is smaller and the reversion rate of the foam droplet is larger,compared with the

关 键 词：安全工程 细水雾液滴 泡沫灭火剂 高温金属表面 铺展特性 传热能力 

分 类 号：X932[环境科学与工程—安全科学]