纵向风下隧道火灾顶部排烟烟气温度分布研究

Study on Temperature Distribution of Tunnel Fire Under Effects of Longitudinal Ventilation and Ceiling Smoke Extraction

建立全尺寸隧道火灾三维数值计算模型,通过设置3种不同的火源位置、风口尺寸、排烟量、火源功率,研究在纵向风速为临界风速时,隧道火灾单点排烟顶壁纵向烟气温度分布特性。研究发现,纵向风下的顶部排烟时隧道顶壁烟气温度随着离火源距离的增大而逐渐减小,且在风口处骤减;顶壁烟气温度随火源热释放率的增大而增加,而火源位置、排烟口长度以及排烟量对顶壁温度影响不大。通过理论分析的方法,得到了的纵向温度衰减公式,建立了不同火源位置下,不同风口长度顶壁纵向温升的衰减模型。

The three-dimensional numerical simulation model of a full-scale tunnel fire was developed to study the temperature distribution characteristics of longitudinal ventilation critical velocity and ceiling smoke exhaust on the top wall of a tunnel fire by setting three different fire source locations,tuyere size,smoke exhaust volume,and fire source heat release rate.The study found that the ceiling smoke temperature at the top of tunnel under the longitudinal ventilation and ceiling smoke exhaust gradually decreases with the increase of the distance from the fire source,and drops suddenly at the smoke exhaust vent.The ceiling smoke temperature increases with the increase of the heat release rate of fire source.However,the position of the fire source,the length of the smoke exhaust vents and smoke exhaust volume have little effect on the ceiling exhaust temperature.And based on the longitudinal temperature attenuation formula established by Fan and Ji et al.,the attenuation model of the longitudinal ceiling temperature rise with different tuyere lengths under different fire source positions was established.