Numerical Simulation Research On Fire Smoke Characteristics Of Double-deck Railway Passenger Cars In Operation

Double-deck passenger cars have the characteristics of large passenger capacity,more flammable materials carried by passengers,and complex internal structure of the carriage.At present,there are few researches on double-deck passenger car fires,and the fires of double-deck passenger cars in static state are basically studied.In a fire accident,fire smoke is an important cause of endangering the lives of people,so it is very important to study the fire smoke characteristics of double-decker passenger cars in operation.Taking a carriage of a double-decker train as the research object,a fire numerical simulation model is established through FDS(Fire Dynamics Simulator),and the large eddy simulation method is used for numerical calculation to study the rupture position of the escape window,the position of the fire source,and the passenger car in the running state.The influence of operating speed and cross wind on the temperature field distribution,flue gas flow,flue gas concentration and other flue gas characteristic parameters in the double-decker passenger car.When the fire source is located in the middle of the lower deck of a double-decker passenger car and the train is running at a speed of 50 km per hour,the effect of the rupture position of the escape window on the fire smoke characteristic parameters is studied.The results show that when the escape windows at the front or rear of the double-decker passenger compartment break separately,it is not conducive to exhaust the smoke in the compartment,and the smoke concentration and temperature in the compartment are harmful to the life and safety of passengers;the escape windows at both ends of the current rear rupture at the same time At the time,the smoke exhaust effect in the upper and rear areas of the compartment is better,and the smoke concentration and temperature are lower,which is beneficial to the escape of passengers.When the train runs at a speed of 50 km/h and the escape windows at the front and rear ends of the carriage are broken,the influence of different fire source positions on the characteristics of the smoke in the train compartment is: when the fire source is located at the front of the carriage,the smoke concentration and temperature in this area are relatively high.High,not conducive to the evacuation of passengers.The smoke exhaust effect in other areas is better,and the smoke concentration and temperature are not threatening to the lives of passengers;when the fire source is located in the upper or lower middle of the car,the smoke exhaust effect at one end of the car and the area where the fire source is located is poor.In addition,the flue gas concentration and temperature are high,and the flue gas environment is very unfavorable for passengers to escape and evacuate.When the fire source is located in the middle of the lower compartment and the escape windows at both ends of the compartment are broken,the internal smoke characteristics parameters of the double-decker passenger car running at different speeds are studied,and the results show that: Almost all the smoke in the two-position area is evacuated,and the concentration and temperature of the smoke have no effect on the life and safety of passengers;the operating speed has little effect on the characteristics of the smoke in the upper deck of the car and the two-position area at the end of the car;The speed has a greater impact on the characteristics of the flue gas in the lower compartment and the one-end area at the front end of the compartment.The higher the operating speed,the lower the smoke concentration and the lower the temperature in the lower compartment and the one-end area.The rate of being discharged outside the vehicle is also greater.When the cross wind speeds are 20 m/s,15 m/s,13.89 m/s,10 m/s,5 m/s and no cross wind,the characteristics of the smoke flow after a fire in the double-decker passenger compartment,The flue gas concentration changes and the temperature field distribution in the cabin are studied.The results show that when the cross-wind speed is greater,that is,the angle between the synthetic wind direction and the running direction is greater,the stable value of the smoke concentration in the upper layer of the car,the first end of the car,and the second end of the car is lower.The better it is for the safe evacuation of passengers.The temperature field distribution in the cabin is consistent with the flue gas distribution.Under different cross-wind conditions,the flue gas temperature in the passenger compartment area where the fire source is located exceeds the safe escape temperature that passengers can withstand,which is very unfavorable for passengers to escape.