火灾时隧道内烟流流动状态试验研究

通过大比例火灾模型试验,研究火灾时隧道内烟流流动状态、烟流速度变化以及通风对烟流流动状态的影响。试验模型隧道长100m,内径1.8m。火源采用燃烧床盛放油料模拟,试验中设定了A、B、C三个火灾规模用以模拟实际隧道火灾场景。试验结果表明,点火后,隧道内火区、火区下游烟流速度在2～8min内增加很快,明显大于点火前风速,且其增幅随通风风速、火灾规模的不同而变化。同时,随着火势的逐渐减弱隧道内烟流速度也逐渐减小,并趋于初始风速。试验结果建议对于一般的限制或禁止油罐车通行的隧道,火灾时,隧道内应尽快建立起2～3m/s的纵向风流以抑止烟气的逆流。

An experimental study of smoke flow in tunnel fire

To investigate the behaviors of smoke when fire occurs in a tunnel,a series of fire tests were conducted in a large-scaled model tunnel.The scopes of the tests include smoke flowage,variation of smoke velocity with time and effect of forced ventilation on smoke flowage.The model tunnel is 100 m long,and it has a circular cross-section with an inner diameter of 1.8 m.An oil pool is employed as a fire source.Three levels of fire loads,categorized as A,B and C,are employed to simulate different fire scenarios.The results show that the smoke velocity at the fire point and in the area behind the fire point increases significantly from 2 min to 8 min after ignition.The increment of velocity varies with forced ventilation and fire load.The smoke velocity gradually decreases to the original value in the tunnel while fire attenuates.The results suggest that a longitudinal forced ventilation of 2~3 m/s should be established as soon as possible to prevent back-flow of hot smoke in case fire breaks out in a tunnel that prohibits tank trucks.