Researches On The Distribution Of The Smoke Flow Of The EMU Fire And Ventilation Control Model In The High-Speed Railway Tunnel

In the wake of building high-speed railway on a large scale, large numbers of tunnel projects will occur. Accompanied with the traffic flow’s rapid increase with each passing day, the probability of the tunnel fire is on the rise. It has great importance for the guarantee of traffic safety, disaster prevention and rescue by doing research on the distribution character of the smoke flow and ventilation control model in high-speed railway tunnels.By using the3D time related viscous compressible fluid Reynolds average Navier-Stokes equation, k-s two-equations turbulent model of fully modified buoyancy and dynamic grid technique, the influence of the air flow on the smoke flow during the braking and stop process of the EMU in the tunnel after the fire broke out under the bottom of the vehicle while moving was simulated. For the convenience of comparison, the fire under the vehicle when the EMU is static in the high-speed railway was analyzed. Meanwhile the ventilation control model of different fire scenario was disused. The main results are as follows:Under static fires, the fire plume firstly bifurcates and then converges at the top the tunnel in single-line tunnel, while the fire plume leans to the left when in double-line tunnel. Equidistance to the fire center at the same condition, the temperature and smoke fraction in a single tunnel are higher. The top of the tunnel downstream is firstly heated. High-temperature area expands from the top down and the stratification of the smoke flow is obvious in a cross section.Under moving fires, the smoke flow diffuses to the back of the vehicle firstly during the braking process; then the smoke flow turns to the front of the vehicle with the vehicle speed gradually decreased; the wind caused by the moving train controls the track of the smoke flow and the smoke flow transfers to the downstream quickly after the stop of the vehicle. At the same time counter flow occurs, with the decreasing of the air flow the length of the counter flow increases. The stronger the fire load is, the farther the smoke can reach in downstream and the longer the counter flow is. The nearer the fire place to the tail car is, the more covered area of the vehicle by smoke flow can be and so the higher the danger coefficient is.In case of fire under the middle carriage of the EMU while moving, it’s supposed to take positive ventilation which can accelerate the transfer of the smoke to downstream along with the air flow. Hysteresis quality of the tunnel ventilation leads to the reinforce of the counter flow and compresses escape space. The ventilation and smoke discharge model in tunnel should be established as quickly as possible to prevent the counter flow.