Study on Fire Characteristics of Subway Train Running with Fire

Abstract

When the train was running with fire on the tunnel, velocity field and smoke diffusion laws inside the subway tunnel and train cars were studied based on dynamic grid technology by considering the coupling of the flow fields inside and outside the cars. Influences of forward and reverse ventilations to the fire development were also compared. Results showed that curves of piston wind inside the subway tunnel obtained by numerical calculation was the same with test result and the two showed good coincidence. When the first car of the train caught fire on the external bottom, the smoke inside the tunnel diffused upstream along the car bottom. When the train speed decreased, the smoke diffused then downstream under the action of piston wind, with temperature kept between 492K-455K. The car interior was influenced slightly by high-temperature smoke. In the state of forward ventilation, the distribution mode of smoke inside and outside the car are basically the same. With reverse ventilation, smoke inside the tunnel backflows and the train would have been surrounded by high-temperature smoke. A great deal of high-temperature smoke would flow into the car, thus reverse ventilation shall be avoided.