Simulation Research On Smoke-blocking Performance Of Air Curtain On Subway Platform

Most subway stations are underground,and there are few channels connected to the outside world.When a fire occurs in the station,a large amount of high-temperature toxic smoke generated by the fire will pose a life threat to the evacuees,especially in the deepest platform layer.In order to avoid casualties,it is necessary to control the smoke in the fire layer to prevent the smoke from spreading to the station hall.Therefore,this paper sets up an air curtain at the stairway connecting the platform layer and the station hall layer to study its smoke blocking performance.In this paper,a subway station in Hefei is taken as the research prototype.Based on the fire simulation software Pyro Sim,a full-scale numerical model of the subway station is established.Through orthogonal test,the main three influencing factors of the fire on the platform layer affecting the smoke blocking effect of the air curtain are : jet wind speed,jet angle and nozzle width.The specific research conclusions are as follows :(1)Through theoretical analysis,the main factors affecting the smoke blocking performance of air curtain are : jet velocity,jet angle and nozzle width.(2)Sixteen simulation schemes with three factors and four levels were designed by orthogonal test analysis.Through FDS numerical simulation,when the fire source power is 2MW and the fire source is 10.5m away from the air curtain,the optimal jet wind speed of the air curtain is 6m/s,the jet angle is 15°,and the optimal nozzle width is 0.35 m.The primary and secondary relationships of the three important factors affecting the smoke blocking performance of the air curtain are : jet angle >nozzle width > jet wind speed.(3)The optimal jet velocity of air curtain under different fire source positions and different fire source powers is analyzed by FDS numerical simulation.The visibility,overall temperature and temperature of measuring points in the station are compared.It is concluded that when the fire source is 15 m away from the air curtain,the optimal jet velocity is 4～5m/s.When the fire source is located in the middle of the platform,the optimal jet velocity is 3～4m/s.When the fire power is 1.5MW,the optimal jet velocity is 3 ～ 4m/s.When the fire power is 2.5MW,the optimal jet velocity is 6～8m/s.(4)Through FDS numerical simulation,the smoke control effect of three working conditions of opening mechanical smoke exhaust alone,opening air curtain alone,opening air curtain and mechanical smoke exhaust simultaneously was studied.By comparing the smoke spread,visibility,the overall temperature of the station,and the temperature of the measuring point,it is concluded that the simultaneous opening of the air curtain and mechanical smoke exhaust can well limit the smoke to the platform layer and prevent the smoke from spreading to the station hall layer through the stairway.Figure [38] table [16] reference [64]...