Study On Fire Prevention And Smoke Exhaust Optimization Of High-speed Train Compartment And Optimal Running Speed Under Broken Windows

China’s high-speed railway,as the main means of transportation for citizens,is developing rapidly.At present,China has mastered a complete set of high-speed railway construction systems under various complicated conditions,and its operation speed,total mileage and passenger flow rank first in the world.At the same time,train safety has attracted the attention of scholars at home and abroad.Due to the high speed train belong to typical inside limited space,the fuel type is complex,there is a fire after the fire spread quickly,plume form complex,large flue gas concentration and high temperature,the rescue work difficult to rapidly expand,easy to form the heavy casualties and economic losses.At present,the emergency plan for high-speed train fire at home and abroad shows that the train should run at an appropriate speed to the nearest evacuation point after fire.Therefore,the smoke prevention and evacuation method and the speed of train fire under the action of multiple coupling factors have high research value.In this paper,the second-class seat car of a single CRH380D EMU is taken as the research object.The FDS model is constructed through many field investigations.The optimization of smoke prevention and exhaust is studied on the basis of the original emergency ventilation system of the train.On this basis,the development and change of fire in the train compartment after the emergency window is broken is studied,and the optimal running speed of the train under the broken window is finally determined.The results show that:（1）To a certain extent,increasing the smoke exhaust volume will effectively reduce the compartment temperature and fire smoke concentration,but the impact on the compartment temperature and fire smoke concentration will be significantly reduced when the smoke exhaust volume exceeds a certain value.In this study,considering the economy and feasibility,the best smoke exhaust volume is 2.02m~3/s;（2）To a certain extent,increasing the fresh air volume will change the air distribution and pressure environment in the compartment and improve the smoke exhaust effect.However,the compartment fire will develop in a more unfavorable direction after the make-up air volume of a single make-up outlet of the emergency ventilation system exceeds 1750m~3/h;（3）Before the fire enters the flashover stage,the broken window will effectively reduce the temperature and smoke concentration in the compartment.300 s after the fire,the broken window will rapidly increase the fire heat release rate,compartment temperature and smoke concentration,which poses a great threat to the safety of passengers;（4）When the train is running at 20km/h,40km/h and 60km/h,the maximum temperature,maximum concentration and the height of smoke layer in the later stage of fire development do not change much with the increase of train speed.After a fire breaks out inside the train compartment,passengers should evacuate to the next compartment as soon as possible,and the train can run at a speed of no less than 60km/h to the nearest evacuation point to wait for rescue.Based on the existing emergency ventilation system of the train,this paper studies the influence of fresh air on the fire spread in the train compartment after the window is broken and proposes the best running speed of the train after the window is broken,which provides a scientific theoretical basis for the fire fighting foundation of high-speed train.