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

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.