CFD-Aided Tenability Assessment of Railway Tunnel Train Fire Scenarios

Five fire scenarios have been simulated with the CFD model Fire Dynamics Simulator (FDS) to analyse the performance-based fire safety design of a 2935 m-long railway tunnel. The influence of tunnel longitudinal ventilation fan activation time, fire size and the type of burning materials on tunnel tenability was investigated based on variations of two primary scenarios: Scenario #1 assumed a 15 MW fire at the front end of a train, and Scenario #2 assumed a 15 MW fire at the rear of a train. In both scenarios the burning material was assumed to be predominantly polyurethane, and tunnel fans were assumed to activate 901 seconds after fire initiation. Scenario #3 was a variation of Scenario #1 with the dominant burning material changed to wood; Scenario #4 was a variation of Scenario #2 which assumed that fans activated 180 seconds after fire initiation; and Scenario #5 was a 6 MW fire, which was scaled down from the 15 MW fire of Scenario #1.