Study On The Performance Of Compressed Air Foam Fire Fighting In Rescue Station Of Extra-Long Railway Tunnel

The railway is an important means of transportation.As the railway tunnel becomes longer and longer,the structure becomes more and more complex,which leads to the increasing risk of fire.Because the tunnel is narrow,the working space is limited,the water supply is difficult,once the fire occurred,which is difficult to rescue.The compressed air foam system has the advantages of small size,easy operation,high water saving and high efficiency.Based on this,this paper focuses on the feasibility and advancement of the compressed air foam fire extinguishing system in the railway tunnel rescue station.This paper selected the railway tunnel rescue station model with the heat release rate measuring equipment which size is 30*6*6m.The train model is made of container,and the height and width of the model is 3m*2.4m according to the aspect ratio of the actual car compartments.Taking into account the actual requirements of the budget and fire-extinguish experiments,the length of the compartment model is 6m which is 1/4 of the actual length.In this paper,firstly,the uniqueness of the compressed air foam fire extinguishing mechanism in tunnel is analyzed separately,and the control equations of foam accumulation effect on freight train and passenger train are summarized.The acceptance ratio is put forward to measure the actual spraying effect of the compressed air foam releasing device.The effectiveness of this parameter was verified by cold jet test,and the compressed air foam releasing tube was selected as the test release mode.Secondly,through full-scale fire experiments,the freight train model using 96 plastic cup standard combustion which the HRR can reach 17.4MW;the passenger train model using 60 standard combustions,9 fiberglass suitcases,9 suitcases and 6 PU polyurethane filled 8kg cloth woven bag which the HRR can reach 19.92 MW.The results can meet the demand of high heat release rate of 10 MW in freight train and passenger train model fire.Thirdly,carried out the fire-extinguish experiments whoes engineering parameters were 10 times of foam expansion ratio,6.5L/(min*m2)of liquid supply strength and 72 m2 of protection area.Two times of fire-extinguish experiments on freight train carriages were completed in 20 minutes and 14 minutes,and a large amount of combustion was left inside the car.In the second experiment,the installation angle of the release pipe was optimized,and the time of fire-extinguish was shortened.Meanwhile,it was proved that the different receiving ratio would affect the effect of fire extinguish.In the experiment of passenger train,the fire extinguishing action is controlled by the time point.The actual result shows that the compressed air foam has finished the fire fighting inside the carrige,and most of the combustion inside the carrige was in good condition.Innovative summary:(1)The uniqueness of the fire suppression mechanism of compressed air foam in tunnel is analyzed;(2)In the large scale rescue station model,the standard fire test was carried out on the scale of more than 10 MW,and most of the present studies were supplemented by small-scale fire;(3)According to the particularity of the compartment in the train fire,the fire extinguishing method of the release tube and the Y type nozzle is used to achieve better fire extinguishing effect.