Experimental and numerical study on the smoke and velocity distribution in an extra-long railway tunnel fire

In order to fully understand the change of the escape environment in the process of an on-fire train moving to the rescue station at a constant speed, a 1:50 small-scale model experiment and full-scale numerical model were carried out to study the smoke control and flow field in a railway rescue station. The results show that after the train has been stopped for 6 min, the rescue station is full of smoke, and all cross passages except for 1# near the entrance of the rescue station have smoke in them. After the train has been stopped for 6 min, the piston wind speed at the entrance of the rescue station decreases to 1.26 m/s, the maximum velocity in the 1# and 2# cross passages is -1.7 m/s, and the velocity in the other cross passages is smaller, all within 0.5 m/s. The high temperature range (more than 328 K) at human eye-level upstream and downstream of the fire source expands to 230 m and 900 m in a full-scale tunnel. The maximum temperature at human eye-level near the fire source increases to 550 K. A smoke exhaust rate of 0.0049 m3/s in the shaft and air supply volume of 0.0098 m3/s in the parallel pilot can ensure that there is no toxic smoke in the cross passage.