Abstract: In order to study the fire development characteristics of high-speed running train roof fires in subway tunnel, a series of moving fire experiments were conducted on a constructed downscaled tunnel train model, setting up different train running speeds and heat release rates, and full-scale numerical simulations were combined to reveal the evolution law of the fire characteristics of high-speed train roof fires in a tunnel（20～150 km/h）. The experimental results show that the maximum temperature on the train roof shows a trend of increasing and then decreasing with the increase of train running speed, in which the maximum temperature change reaches 205 °C; Moreover, with the increase of train running speed, the vertical flame height gradually decreases, and the horizontal flame length shows a trend of increasing and then decreasing, and the critical running speed increases with increasing heat release rate, which is verified by numerical simulation. Combined with the scaled-down experimental study, a segmented prediction model of the flame length of the roof fire of the running train in the tunnel was proposed.

Key words: tunnel train fire, moving fire, flame shape, temperature distribution