Research On Natural Smoke Exhaust Characteristic Of Fire Smoke In Waiting Hall For High-Speed Railway Station

Fire smoke is the main factor leading to casualties,aiming at the problem of instability of natural smoke exhaust in waiting halls for high-speed railway stations,which are susceptible to window openings and external environment.This paper uses a combination of theoretical analysis and numerical simulation to study the fire smoke and natural smoke exhaust technology for waiting hall,analyzed the process of ceiling jet and smoke filling,explored the influence of the window structure on natural smoke exhaust ability of the upper and lower hanging windows and finally distinguished the discrepancy of natural smoke exhaust effect between upper and lower hanging windows in the waiting hall.The research of this paper provides theoretical guidance for the scientific selection of natural smoke windows and strategies of smoke control in waiting halls.Aanlyzed the fire characteristics and natural smoke methods of waiting hall based on a station and the research model for waiting hall is constructed.Using FDS software,the rules of ceiling jet and smoke filling were studied under different fire power and space height and modified the ceiling temperature and velocity attenuation model through the dimensionless processing of the smoke characteristic parameters;The change process of smoke layer height over time was determined by N-percentage method,and compared with NFPA 92B and Zukoski models,it was obtained that the theoretical model was applicable to smoke layer height not less than 1 m;The smoke filling rate is directly proportional to the fire power,but has little relationship with the space height.The smoke filling rate at the fire power 8 MW is 3.4 times higher than 1.5 MW while it only 0.006 m/s difference between the height of 20 m and 10m.Fire power is the main factor leading to faster filling speed.A research model for the natural smoke exhaust capability of a single hanging window was constructed.The smoke exhaust capability and wind resistance of the upper and lower hanging windows were systematically studied when there is only hot pressure,wind pressure and the combination of hot and wind pressure,the main smoke and wind inlet area are analyzed.It is concluded that the upper hanging window has a large smoke resistance and weak wind resistance while the lower hanging window has a small smoke resistance and strong wind resistance.With the equal opening angle,the lower hanging window can not only discharge more 52?61%smoke than the upper hanging window,but also reduce the air entering the room by 60%.The critical failure wind speed for lower hanging windows is also increased by at least 0.7 m/s compared with upper hung windows.Based on the above research,the natural smoke effect with the hanging windows installed on the waiting hall is analyzed,and it is found that both upper and lower hanging windows can effectively discharge the smoke under windless environment,and the temperature,visibility and CO concentration meet the requirements for safe evacuation of personnel.However,the total smoke exhaust volume of the lower hanging window is 30%higher than the upper hanging window,and the smoke temperature is relatively lower;When the wind speed is 3 m/s,the natural smoke exhaust of the upper hanging window fails,and the visibility is less than 10 m,which does not meet the requirements for safe evacuation of personnel,while the lower hanging window can still effectively exhaust smoke.Finally,corresponding smoke control suggestions are put forward for the natural smoke exhaust in the waiting hall.