公路隧道排烟耦合细水雾灭火研究

摘要

This paper aims to study fire suppression effects of different heat release rates in highway tunnel by combined smoke exhaust system with water mist, and to discuss the suppression effects of water mist when turned on the smoke exhaust at different time.Based on Fire Dynamics Simulator, the simulations were carried out when the heat release were 4MW and 2.5 MW, respectively.And the smoke exhaust system was turned on at the moment of 60 seconds, 120 seconds,and 150 seconds from fire start,respectively.Following parameters are discussed to analyze the heat release rate of pool fire, the average temperature over oil surface, the volume percentage of CO in the air at 1.5 meters height in the tunnel.Results show that when the heat release rate of the fire in the highway tunnel was 4 MW, smoke exhaust system was helpful to extinguish the fire.The suppression effect was the best when the smoke exhaust system and water mist worked at the same time.When the heat release rate was 2.5 MW, the extinguishment time was the shortest when the smoke exhaust system and water mist worked at the same time, the suppression effect was better when turned on the smoke exhaust system at 60 seconds comparing with the situation when smoke exhaust system was turned on at 150 seconds.The simulation results show that though the smoke was well controlled when the smoke exhaust system was turned on, the suppression effect was different if the heat release rate was different in the condition of smoke exhaust system combined with water mist system.The start time of smoke exhaust system should be well controlled with consideration of the different heat release rate.%目的 分析公路隧道排烟与细水雾共同作用下,对不同功率火灾的灭火效果,讨论不同排烟时间对细水雾灭火的影响.方法 应用FDS软件对公路隧道4MW和2.5MW功率火灾模拟,设定排烟60s、120s、150s启动.对火源热释放速率变化、火源根部温度及1.5m高度CO体积分数进行分析.结果 公路隧道火灾功率为4MW时,开启排烟有助于隧道细水雾灭火,排烟与细水雾同时启动工况的灭火效果最佳.火灾功率为2.5MW时,排烟与细水雾同时启动工况的灭火时间最短,60s开启排烟工况灭火效果优于150s排烟工况.结论 排烟与细水雾耦合作用对隧道火灾灭火效果的影响与火灾功率有关.尽管排烟启动时间不同,对细水雾灭火效果的影响各异,但排烟对隧道内烟控效果有利.