Influence Of Piston Wind On Smoke Diffusion In Tunnel Rescue Station And Smoke Exhaust Design Method

When the train travels in the tunnel,the air flow is driven to form the piston wind,and the piston wind will cause the redistribution of the flow field in the tunnel.Affected by the piston wind,the smoke diffusion law and the smoke exhaust effect of the smoke exhaust system when the moving train catches fire in the tunnel will be different from the situation when the fire source is stationary.Relying on the Mabaishan Tunnel in Qinling Mountains,this paper studied the calculation method of piston wind in the process of train traveling within the railway tunnel emergency rescue station,the smoke diffusion law under the action of piston wind and the design method of smoke exhaust in the rescue station under its influence.The following results were achieved:1.The generation mechanism of piston wind was analyzed,and the basic assumptions and influencing factors for calculating piston wind were given.The calculation methods of piston wind in the process of train traveling when a single train is traveling in the tunnel and two trains are driving in opposite directions were deduced,and the theoretical analytical solutions of the piston wind in the two cases were obtained.The consistency was verified by numerical simulation of Fluent software.The influence laws of the train speed in the single train traveling or the distance between the two trains in the two trains traveling at the opposite direction on the piston wind were proved.2.Based on the Fluent dynamic grid technology,the smoke diffusion law in the head and middle of the train parked in the emergency rescue station was verified.And the smoke diffusion law of the train’s head,middle and rear fire in the cases of single train traveling and two trains traveling in the opposite direction were given.The smoke diffusion length of the train on fire in the emergency rescue station with or without piston wind was obtained.3.The attenuation process of the piston wind after the train stopping was proved,and the attenuation laws of the smoke exhaust efficiency under different driving conditions and different ignition positions were obtained by the piston wind.Considering the influence of the piston wind,the paper studied the smoke diffusion law and the smoke exhaust efficiency under the influence of different flue duct positions,flue duct sizes and flue outlet wind speeds in the emergency rescue station.In this way,the best design position of the exhaust duct was determined,and the exhaust design scheme suitable for the fire in different positions of the train in the actual project was formulated.The above research results directly guide the integrated project of the thesis-the Mabaishan Tunnel in Qinling Mountains,and can also provide a reference for the research on the design method of smoke exhaust for railway tunnels.