A prediction model for smoke exhaust efficiency of rescue stations in railway tunnels with semi-transverse ventilation

This study analyzes the effects of heat release rate (HRR), fire position, smoke exhaust velocity, shaft diameter, and ambient pressure on the smoke exhaust efficiency in a rescue station with semi-transverse ventilation. The results demonstrate that the shaft close to the fire source has higher smoke exhaust efficiency, but the fire location has little effect on the overall smoke exhaust efficiency. The smoke exhaust efficiency decreases with the increase of HRR and is proportional to the -1/3 power of the dimensionless HRR. Before the smoke is overall controlled in the rescue station, increasing the smoke exhaust velocity can improve smoke exhaust efficiency, and the smoke exhaust efficiency is proportional to the 2/3 power of the dimensionless smoke exhaust velocity. When the smoke in the rescue station is overall controlled, increasing the exhaust velocity can reduce the smoke spread distance. Moreover, the smoke exhaust efficiency is proportional to the 9/5 power of the dimensionless shaft diameter and 0.3 power of the pressure ratio. Finally, combined with theoretical analysis, a prediction model of the smoke exhaust efficiency is obtained. Therefore, this study can guide the design of the semitransverse ventilation system in extra-long railway tunnel rescue stations at different altitudes.