摘要
针对自然通风下隧道火灾非对称双火源协同作用下火焰特性和顶棚射流烟气最高温度开展研究。在缩尺寸隧道火灾模拟试验平台开展试验,结果表明,随着火源间距的增大,非对称双火源由完全融合到间歇融合,最后完全分离。火焰完全融合且火源热释放速率不同时,火焰呈现非对称形态,存在一个火焰高度,火焰高度主要由较大热释放速率火源决定。随着火源间距的增大,存在两个火焰高度,火焰高度最大值均大于对应工况火焰完全融合时的火焰高度。双火源一侧接收到的辐射热流随离开火源距离的增大而减小,固定水平位置处接收到的热辐射随着火源间距的变化会有波动,但整体变化不大。非对称双火源火羽流顶棚射流烟气最高温度整体随火源间距的增大而减小。当S/D<0.5时,烟气最高温度主要受两个火源热释放速率的影响,火源间距对烟气最高温度的影响较小;而当S/D≥0.5时,烟气最高温度主要受对应侧火源热释放速率的影响,而受临近火源热释放速率的影响较小。在此基础上,建立了非对称双火源顶棚射流烟气最高温度分段预测模型。
This paper presents an experimental study on the flame characteristics and maximum ceiling smoke temperature generated by two asymmetric fires in a tunnel under natural ventilation.A series of experiments were conducted in a reduced-scale tunnel,considering two unequal fires with three different heat release rates and five varying fire separation distances.A camera was employed to capture the behaviors of the flames,while four water-cooled heat flux meters were utilized to measure the heat flux at one side of the two fires.A set of thermocouples was positioned beneath the tunnel ceiling to monitor the temperature of the smoke near the ceiling.The experimental findings indicated that as the fire separation distance increases,the flames from the two asymmetric fire sources exhibite three distinct stages:complete merging,intermittent merging,and separate flames.During the fully merging stage,when the two heat release rates are unequal,an asymmetric flame is observed,with a single flame height determined by the larger fire.As the fire separation distance increases,two distinct flame heights emerge,with the height of the larger flame exceeding that observed in the same fire scenario during the fully merging stage.The heat flux decreases as the distance from the fire increases,and at a specific horizontal position,there is minimal change in the heat flux with increasing fire separation distance.Furthermore,the maximum temperature of the smoke flow,generated by the ceiling-jet resulting from two asymmetric fires,decreases as the fire separation distance increases.When the dimensionless fire separation distance(S/D)is less than 0.5,the maximum smoke temperature is primarily influenced by the heat release rates of the two fires,with the effect of fire separation distance being negligible.However,at a dimensionless fire separation distance of 0.5 or greater(S/D≥0.5),the maximum temperature is predominantly determined by the corresponding fire heat release rate,while the influence of nearby fire heat release rate becomes minimal.Based on this analysis,a segmented prediction model was developed to forecast the maximum temperature of smoke generated by a ceiling jet of two asymmetric fires within a tunnel.
作者
孟娜
杜晓燕
MENG Na;DU Xiaoyan(College of Safety and Environmental Engineering,Shandong University of Science and Technology,Qingdao 266590,Shandong,China;School of Civil Engineering and Architecture,Anhui University of Technology,Ma'anshan 243032,Anhui,China)
出处
《安全与环境学报》
北大核心
2025年第1期50-57,共8页
Journal of Safety and Environment
基金
国家自然科学基金项目(51974175)。
作者简介
孟娜,副教授,博士,从事隧道火灾防治研究,mengna@sdust.edu.cn。
