不同坡度隧道火灾烟气温度分布特性的研究

A Study on the Temperature Distribution Characteristics of Smoke in Tunnel Fires with Different Slopes

为了分析不同隧道坡度对火灾烟气温度分布特性的影响,本文利用FDS数值模拟方法对坡度为0%~10%的隧道顶棚烟气纵向温度分布和最高温度展开了系统性分析,提出了不同条件下顶棚最高烟气温度预测模型。结果表明,隧道坡度对于纵向烟气温度的影响分为两部分,近火源区域坡度影响较大,烟气温度随坡度的增加而减小,且坡度越大,最高烟气温度的位置向火源下游偏移的距离也就越大;远火源区域坡度影响较小,坡度的增加,使得隧道进出口高程差增大,烟囱效应引起的纵向诱导气流运动速度随之增加,使得火源下游烟气的纵向运动加快,导致热烟气与隧道壁面、冷空气之间的热传递效应增强,热量损失增多,从而导致火源下游烟气温升衰减速率加快。基于前人经典最高烟气温度预测模型,引入了隧道坡度的影响,发现最高温度与隧道坡度呈线性关系,基于模拟实验数据建立了考虑隧道坡度影响的最高烟气温度预测模型。

In order to analyze the influence of different tunnel slopes on the fire smoke temperature distribution characteristics,the longitudinal temperature distribution and the maximum temperature of the smoke from the roof of the tunnel with a slope of 0~10%were systematically analyzed by using FDS numerical simulation,and a prediction model for the maximum smoke temperature of the roof under different conditions was proposed.The results show that the influence of the tunnel slope on the longitudinal flue gas temperature is divided into two parts,the influence of the slope is larger in the region near the fire source,the flue gas temperature decreases with the increase of the slope,and the larger the slope is,the location of the maximum flue gas temperature is offset to the downstream distance of the fire source,and the influence of the slope in the region far away from the fire source is small;the increase of the slope makes the difference in the tunnel inlet and outlet elevation increase,and the velocity of the longitudinal induced airflow due to the chimney effect increases,making the downstream distance of the fire source increase.The increase of slope makes the elevation difference between the entrance and exit of the tunnel increase,and the longitudinal induced airflow motion rate caused by the chimney effect increases,which makes the longitudinal motion of the smoke downstream of the fire source accelerated,leading to the enhancement of the heat transfer effect between the hot smoke and the wall of the tunnel and the cold air and the increase of heat loss,which leads to the accelerated decay rate of the temperature rise of the smoke downstream of the fire source;based on the classical maximum smoke temperature prediction model of the previous work,the influence of the tunnel slope is introduced,and the maximum temperature is found to be in a linear relation with the slope of the tunnel.Based on the simulation experimental data,the maximum smoke temperature prediction model considering the influence of tunnel slope is established.