Numerical Simulation Of Fire Smoke And Ventilation Controlling In Subway

While the developing of the social economy, with advantages of fast, comfortable, environmental and big passenger capacity subway has already been the mean development direction of the traffic. Now, in domestic, more than 30 cities have carried out the construction of Rail Transit. Obviously, subway can relieve the traffic congestion, but once on fire, the consequences could be very serious. In recent years, there are many fire accidents happened at home and abroad, which make alarms to people. But how people to take refuge when the train is on fire and what scale the fire reach which leads to the train can not go on running are not defined definitely. Furthermore, when the burning train stopped in the tunnel and took evacuation, the ventilation methods influenced the distribution of smoke temperature and toxicity, but, still lack comprehensive ventilation study on specific fire scenario. Therefore, study and analysis on the critical fire scale of the running train and the tunnel ventilation is very important for emergency rescue and people evacuation.There are two study methods about fire, which are experiments and simulations. Comparatively, the numerical simulation method with the advantages of less-comsuption, short-period and good-repetitiveness, have been adopted widely as the computer quick-developing. As one of the computer simulation methods, CFD (Computational Fluid Dynamics) has advantages on the fire smoke simulation. Now, there are many software packages for CFD, such as: FLUENT, PHOENICS, SMARTFIRE, STAR-CD, FDS etc. And FLUENT can be used to compute fluid flowing, mass and heat transfer, chemical reaction such as combustion etc, moreover, it could self-adapt to the grid, so FLUENT is widely used in many industrical areas.Subway fire is an unsteady, turbulent combustion process, and the smoke flow is also a three-dimension, unsteady and turbulent process. In the paper, based on the analysis on the probability of the subway fire and the combustible materials in subway, established mathematical models for the numerical simulation of smoke and physical models of the train and tunnel according to the matro train and the subway tunnel between Xia Wafang-Nan Lou of 1st line in Tianjin Metro, then, took smoke numerical simulation about the train interior fire and tunnel fire respectively with FLUENT software. Finally, through analyzing the smoke flowing, the critical fire scale of the running train is got, which is 5MW. Meanwhile, aimed at the situation that centre burned train staied in the middle of the tunnel, analyzied the smoke temperature, spreading and toxicity on different ventilation conditions in different fire sacle. Furthermore, an"opened-putting off pressured"ventilation method is firstly put forwarded in this paper, which is that all the rolling doors are open, after having ventilated as 60m3/s for 150s in the accidental tunnel, in adjacent tunnel took ventilation of 40m3/s , which is proved to be feasible for people safe evacuation and smoke organizing by numerical simulation.