列车着火后停留在隧道内的火焰烟气逆流临界风速  

The critical velocity of the flame smoke backflow due to the on-fire train in tunnel

作　　者：毛军[1] 郗艳红[1] 李炎锋[2] 

机构地区：[1]北京交通大学,北京100044 [2]北京工业大学,北京100022

出　　处：《土木工程学报》2011年第3期120-127,共8页China Civil Engineering Journal

基　　金：国家自然科学基金(51078031);北京市自然科学基金重点项目(8101004);国家科技部重大基础研究前期专项研究项目(2005CA04700)

摘　　要：防止烟气逆流的临界风速是隧道火灾通风排烟系统设计的主要指标。国内外对纯烟气逆流的临界风速研究较多,对阻塞明显且夹带火焰的烟气逆流问题研究得则很少。通过模型试验和数值模拟,对列车着火阻塞在隧道内形成的夹带火焰的烟气逆流及其临界风速进行分析。考虑列车对隧道的阻塞比和火焰热辐射作用的影响,利用能量方程推导出计算临界风速的新公式,并与Oka-Atkinson公式、Wu-Bakar公式等计算纯烟气逆流的临界风速公式进行比较。结果表明新公式更适用于夹带火焰的烟气逆流的情况。同时还发现,列车中部着火和头部着火情况下的临界风速相近,但与列车尾部着火的临界风速不同;隧道内有列车着火和隧道内着火但无列车情况下的临界风速也有所不同。The critical velocity for preventing the smoke backflow in fire is the key index for design of ventilation and smoke extraction systems,and it is also one of the focuses of studies on tunnel fire.Researches on the critical velocity have obtained some results about the backflow of pure smoke,but the critical velocity of the smoke backflow with flame has not been paid enough attention to in such underground space with large slenderness ratio.Taking the Beijing subway tunnel as an example,the critical velocity of backflow with flame with the on-fire train remaining in the tunnel was analyzed through small-scale model experiments and numerical simulation.Considering the train-tunnel dimension ratio and the role of thermal radiation impact on the critical velocity,a new formula for calculating critical velocity is deduced through the energy equation.The formula is compared with the existing formulas for calculating the critical velocity of the pure smoke backflow,such as Oka-Atkinson formula,Wu-Bakar formula,etc.,and the results show that the new formula is more suitable than the others for calculating the critical velocity of the backflow with flame.It is also found that the critical velocity is not exactly the same for fires on different parts of the train.When fire occurred in the center and the head of the train,the critical velocity is similar;but it is different from fire occurred at the end of the train.When fire occurred in the train within the tunnel,the critical velocity is different from the fire occurred in the tunnel without the train.

关 键 词：隧道 列车火灾 火焰 烟气逆流 临界风速 

分 类 号：TU458[建筑科学—岩土工程] U453.5[建筑科学—土工工程]