Experimental study on the tunnel temperature distribution under the coupling effect of train blocking and fire inside the carriage

The understanding of temperature distribution in a railway tunnel caused by train fire can help to optimize the design of ventilation and rescue systems. In this study, a series of experimental tests were conducted in a 1/11 reduced-scale tunnel to investigate the effect of train blocking and internal fire of the carriage on the maximum temperature distribution. Different fire scenarios were discussed, including blocking length and opening modes of doors and windows under typical longitudinal wind speeds. In order to quantify the high-temperature load in the tunnel, a dimensionless model of the maximum temperature rise under different fire scenes was proposed. The results showed that the maximum temperature under the blocking condition was relatively higher than the non-blocking condition, and the maximum temperature increases with the blocking length at the same measuring point. Besides, the position of the openings, the number of openings, as well as the space of openings all would affect the heat spread, but these factors might have less influence on the maximum temperature in comparison with heat release rate and longitudinal wind speed. These results can assist an optimal ventilation design for train fire in a railway tunnel.