通风窗开启模式对火灾烟气影响的数值模拟

Numerical simulation of the influence of ventilation windows’opening modes on fire smoke

采用FDS(Fire Dynamics Simulator)数值仿真手段对青岛市某在建三层岛式地铁站台火灾情景进行模拟研究.在站台层楼梯处设置一定强度的火源,启动站台通风系统和可调通风型站台门上方的辅助排烟通风窗,模拟了四种不同通风窗开启模式下烟气的蔓延规律,分析了不同通风窗开启模式对烟气分布、温度、CO浓度和可见度的瞬时演化影响.结果表明,在当前的通风设计条件下,不同通风窗开启模式对站台层烟气蔓延具有显著影响.火灾发生360 s时,模式三平均温度较模式一、二、四分别低9.2%,5.4%,2.2%;模式三平均CO浓度较模式一、二、四分别低44.1%,33.6%,7.5%;另外,模式三、四的可见度比模式一、二的高.因此,综合考虑烟气浓度分布、烟气温度、CO浓度和可见度,通风窗开启模式三,即开启双侧站台靠近火源的占总通风口面积一半的通风口具有更好的辅助排烟效果.

The fire scenario in a three-story island subway station under construction in Qingdao is simulated and studied by FDS(Fire Dynamics Simulator)numerical simulation.Fire source with certain intensity is set up at the entrance of a platform stair.The platform ventilation system and the auxiliary smoke exhaust ventilation windows above the adjustable ventilation platform doors are started.The spread of smoke is simulated under four opening modes of the ventilation windows.The instantaneous evolution effect of different ventilation windows’opening modes on smoke distribution,temperature,CO concentration and visibility is analyzed.The research results show that under the current ventilation design conditions,different ventilation windows’opening modes have a significant effect on the spread of smoke at the subway platform.At 360 seconds after the fire,the average temperature of mode 3 is 9.2%,5.4%and 2.2%lower than modes 1,2 and 4 respectively;The average CO concentration of mode 3 is 44.1%,33.6%and 7.5%lower than modes 1,2 and 4 respectively;In addition,the visibility of modes 3 and 4 is higher than that of modes 1 and 2.Therefore,considering the smoke concentration distribution,temperature,CO concentration and visibility,the third opening mode of the ventilation windows,that is,opening half of the total vent area near the fire source on both sides of the platform,has better auxiliary smoke exhaust effect.