The Research On Fire Smoke Spreading And Controlling In Subway Station

With the rapid progress of the economy and the urbanization in China, the subway as an effective vehicle to solve the problem of traffic is developing quickly in our country. It can be said that the 21st century is the epoch of rail-traffic in our cities. But when the subway is working, the fireproofing and lash-up disposal becomes more and more important. Meanwhile it is also an important research task In order to discuss the flowing rule and the control of the smoke, a physical model of a two-layer and island type subway station is established in the paper, according to the structure of most subway station in our country. The three-dimensional field simulation about the spread and control of smoke when a train catches fire in the subway platform is carried out by Fluent. The k ? εturbulent flow model with full buoyancy amendment is used to simulate the gas turbulent transport. Rosseland radiation model is used to compute the radiation heat transmission and SIMPLEC algorithm is used to Reynolds average Navier-Stokes equations. The fire point is simplified as a volumetric source of which the heat productivity varies with time. When the train catches fire in the natural condition, two different fire points is simulated and compared. The more dangerous fire point from is used as the next fire point for the smoke-control simulation. According to the simulation, when the platform layer catches fire, not all the evacuation stair heads will become smoke spout. The stair heads near the fire source will be the smoke spout. The smoke from the spout affected by cool air around and mixed with it loses buoyancy gradually in the mezzanine. Then the smoke flows backward to the platform layer from the stair heads which is far away from the fire source. All of these can provide effective evidences for the control of smoke diffusion. The conclusion is got that safety evacuation will be unsatisfied without mechanical ventilation. In the simulation of smoke control, smoke screen, exhausting smoke in the platform layer, blowing-in from the stair heads and smoke prevention air curtain are combined, analyzed and compared. When the velocity of jet stream from smoke prevention air curtain is more than 10m/s, 6 minutes for safety evacuation will be enough without mechanical ventilation. The relation between wind rate,wind speed and the power of motor are obtained by the performance testing of the smoke prevention air curtain, which provides the gist for the design and manufacture of air curtain.