纵向通风下T型分岔隧道火灾烟气蔓延特性

Fire smoke spread characteristics of T-shaped bifurcated tunnel under longitudinal ventilation

为探究纵向通风作用下T型分岔隧道内火灾烟气蔓延特性,采用火灾动力学模拟软件(FDS),建立分岔隧道全尺寸数值模型,通过改变主隧道内纵向通风风速和分岔隧道内火源功率,研究不同纵向通风风速与火源功率情况下主隧道与分岔隧道内温度分布规律以及流场特征。结果表明:随着纵向通风风速的增大,分岔隧道内上游火灾烟气温度呈现先下降后增大的变化趋势,分岔隧道内速度流场由向火源上游倾斜变为向火源下游倾斜;主隧道内烟气最高温度随纵向通风风速的增大呈现先增大后减小的变化特征,转折风速为2 m/s,且烟气最高温度出现位置基本在火源附近;主隧道内烟气蔓延前锋随纵向通风风速增大逐渐向下游移动,风速为3 m/s时,烟气蔓延前锋已被控制在火源中心线附近。

In order to study the characteristics of fire smoke spread in T-shaped bifurcated tunnels under longitudinal ventilation,a full-scale numerical model of the bifurcated tunnel was established using fire dynamics simulation(FDS)numerical simulation software.By changing different longitudinal ventilation and heat release rates,the temperature distribution and smoke flow characteristics were studied.The results show that:With the increase of longitudinal ventilation,the upstream fire smoke temperature in the bifurcated tunnel decreases first and then increases,and the velocity field in the bifurcated tunnel changes from inclined to upstream of the fire source to inclined to downstream of the fire source.The maximum smoke temperature in the main tunnel increases first and then decreases with the increase of longitudinal ventilation.The turning longitudinal ventilation speed is 2 m/s,and the maximum temperature of fire smoke is basically near the fire source.The smoke spread front in the main tunnel gradually moves downstream with the increase of longitudinal ventilation speed.When the longitudinal ventilation speed is 3 m/s,the smoke spread front is close to the fire source area.