Study On Smoke Diffusion And Ventilation Mode In Subway Fire

Due to the large volume of subway,safe and fast operation,comfortable passenger riding environment,it has become the preferred travel mode for urban residents.When a sudden fire occurs in the subway,if the smoke exhaust effect is not satisfactory,it will cause passengers to inhale the toxic smoke produced by the inadequate combustion of excessive combustible substances,which is the main cause of the large-scale casualties.In this paper,numerical simulation of 2.5MW fire accident in subway island station under different ventilation and smoke exhaust mode is carried out.After the fire occurred on the island station platform,the harmful flue gas temperature,the harmful flue gas height,the minimum opening air volume of the escalator and the air volume of the shielding doors in each mode of the platform were studied.Combined with the data,the ventilation and smoke exhaust scheme with popularizing significance is concluded.The following results have been achieved:(1)The harmful flue gas temperature of both sides of the shield door is higher,and the middle part of the shield door can effectively reduce the harmful flue gas temperature.The temperature of harmful flue gas is higher when one side shield door is opened,and the temperature of harmful smoke can be effectively reduced by opening the middle part of shield door;(2)The distribution of harmful smoke height on both sides of the single side shield door mode is uneven,which indicates that the single side shield door mode has some drawbacks,in the single and double side shield door opening mode,the opening of the intermediate shield door helps to keep the whole harmful smoke height at a higher level;(3)The result of calculating the air volume of the escalator by using the platform flow measuring device shows that the air volume of opening the two side shield door is larger than that of the one side shield door;(4)The ventilation of two side shielding doors is obviously larger than that of opening one side shield doors,except for the two ends and the middle shielding doors,the opening significance of the other shielding doors is not very great.To sum up,the way of opening two side shield door is better than that of opening one side shield door.In addition,in the mode of opening one side or two side shield door,the open mode of both ends and middle shield door has higher significance of ventilation and smoke exhaust.