Research On Smoke Spread Of Subway Fire Compartment

With the development of urban transportation,the subway system has been one of the most common means of transportation,which brings in both conveniences and safety problems.Fire accidents cover the largest proportion of the total accidents.Besides,the most severe consequences of fire accidents are caused by the smoke,since inhaling a larget amount of smoke can lead to anoxia,poisoning or even asphyxia.Given the severe consequences of fire accidents in the subway system,the software simulation are applied to research the spreading of smoke in compartments of subway on fire so as to propose feasible advices for evacuation.Firstly,those combustibles potentially triggering fire accidents are analyzed,and the major reasons of fire accidents are figured out to provide theoretical data for the establishment of models.Secondly,on the basis of observing,organizing and analyzing data,with the actual size of B-type subway train in Hefei City,the PHOENICS software is used to build numerical models and set relevant boundary conditions and parameters.At last,at two different circumstances(i.e.immediate stopping the train and continuing its operation)after the occurring of fire accidents,the influences of different locations and sizes of fire source on the spreading of smoke at the subway train are analyzed.Some conclusions are made as follows:(1).If the subway train immediately stops after the fire accident and the fire source is in the middle part of compartment,the smoke concentration is distributed systematically around the center of fire source.The closer to the fire source it is,the smoke concentration is higher,the temperature is higher and the visibility is poorer.When the fire source is at the junction of two compartments,the influences to the passengers are smaller.When the fire source is in front of the train and the smoke is unevenly distributed,the influences on the evacuation efforts are more significant.When the fire source is at the junction of two compartments or in front of the compartment,the passengers are in greatest danger.(2).In the plane of aisle,areas at a distance of 2 m to the fire source are significantly affected by the temperature.The door closest to the fire source has the highest temperature.In the plane of doors,the door which is closest to the fire source and in the direction of smoke flow has higher temperature and smoke concentration than other doors,but its visibility is lower.(3).If the train continues to run after the occurrence of fire accident,and the fire source is in the middle part of train,the fire source below burns violently.When the firesource is at the junction of two compartments,the smoke spreads poorly,the visibility is bad,the temperature is higher and the smoke concentration is higher.A fire source in the middle part of the train or at the junction of two compartments pose the greatest danger to the passengers.(4).When the volume of fire source goes bigger,the average temperate at the same height continuously increases,and the average smoke concentration arises.