基于燃料可燃界限的隧道火灾回燃研究

地铁隧道属于大长细比的通风受限空间，隧道火灾在一定条件下会出现回燃．地铁隧道1：8缩尺比例的火灾模型实验表明，决定回燃是否产生的关键参数是燃料挥发份的质量分数，单隧道自然通风条件下均临界值为8．78％；利用燃料的可燃界限图所得到的质量分数的临界值为8．66％，与实验值接近．自然通风条件下的单隧道回燃和腔体回燃相似，但产生回燃的燃料挥发份质量分数的，临界值不同．在确定隧道火灾回燃之前，借助于燃料的可燃界限图初步判断其挥发份质量分数临界值的范嘲，对现场真实火灾回燃的分析和控制有重要的参考价值．

Study on Backdraft Occurring in Subway Tunnel Fire Based on Flammability Limits of Fuel

Subway tunnel is a kind of bruited ventilation space with a large slenderness ratio. Backdraft may take under certain conditions in tunnel fire. Some experiments have been conducted to the tunnd fire backdraft by the 1/8 reduced-scale model experimental apparatuses. The results indicated that the mass concentration of the volatilized fuel is the key parameter determining the occurrence of backdraft in subway tunnel fire, and the critical value of the mass conc~entration was equal to 8.78 % in the single-tunnel with natural ventilation. And the critical value can be obtained at the same time from the flammability diagram of fuel, whth was 8.66%. Under the condition of natural ventilation, the characteristics of backdraft occurred in the single-- tunnel was almost the same as that in compartment, while their values were different. Therefore, the flammability diagram of fuel can be used to find the range of the critical values in a real-scale subway tunnel, which will play an impertant role in the fire disaster prevention.