Abstract: In order to explore the influence of relative wind speed on the smoke flow and temperature distribution of high-speed train carriage fire, PyroSim was used to establish a numerical calculation model for fire of a certain type of second-class carriage of China Renaissance. Under the condition of closing the outer doors 3 min after the fire, the influence of the ruptured states of the windows and different relative wind speeds on the smoke flow and temperature distribution of carriage fire was studied, and the safety of the train operation on viaduct under the fire was evaluated. The results show that: for the case of artificially smashing the emergency escape windows, the unilateral opening or the convection opening has no obvious effect on the overall temperature inside the passenger carriage. In the early stage of the fire, the fire mainly spreads to the ruptured side of the escape windows. As the relative wind speed increases, the temperature of carriage aisle decreases, and the time of the smoke reaching the end door of the passenger carriage on both sides increases. In the early stage of the fire, the increase of relative wind speed has more obvious effects on the cooling and smoke exhaust through the platforms on both sides, reducing the scope of the dangerous zone. A small area near the fire source before 50 s is a light-hazard area, roughly (-2, 2) m. The carriage aisle is mostly in the safe area, and the period before 50 s is the best time period for people to escape. Considering the personnel evacuation and the spread of fire, it is proposed that the safe operating speed of the train after a fire is 40 km/h.

Key words: high-speed railway carriage, emergency escape, relative wind speed, simulation study, fire smoke