Study On Extinguishing Experiment And NumericaL Simulation Of Bus Internal Fire

Recently,the events of bus fire emerge in endlessly in China,which caused by serious harm to social stability and security.So it is necessary to research bus fire.The thesis has carried on the experiment and the numerical simulation research of the internal bus fire.The thesis has analysed the bus fire in theory,which are the harm of smoke and smoke toxicity of the weighted evaluation model in the fire and after the fire.Four extinguishing experiments were done in the physical bus with the water mist fire extinguishing system.The fire source is oil pan.The thesis has carried on the experiment research of the internal bus fire,especially the extinguishing effect,the temperature and the smoke toxicity etc.in the water mist fire extinguishing system.The numerical simulation calculation mainly analyzes the three factors of to open windows in different position,to open windows and door in different time,fire location have influence on the temperature,the visibility and the flue gas flow respectively.The thesis has analysed and compared two weighted evaluation model,which are FED model and N-Gas model,through the analysis of the characteristics of the bus fire,in the fire and after the fire smoke harm to human body.The extinguishing experiments spend the shortest time with 4s and the longest time with 9s among the four extinguishing experiments.The above of the fire source reaches the highest temperature,which is 380 ?,the top of the bus reaches 230 ?,the middle of the bus reaches 155?,the bottom of the bus reaches 65?.The minimum content of O2 decreased to 17.9%,the highest content of CO2 reaches 2.2%,the highest concentration of CO reaches 424 ppm,the highest concentration of SO2 reaches 45 ppm,nitrogen oxide only is NO,the highest concentration is 12 ppm,the highest concentration of hydrocarbons reached 373 ppm.The analysis of CO by the FED model is 0.024 and is within 0.1 of the safe value.The comprehensive analysis of the smoke by the N-Gas model is 0.2 and is within 0.8 of the safe value.The temperature of the fire and the toxicity of the smoke are not dangerous to the occupants.Simulation studies have found that the flue gas in the area where the windows opened spreads faster and the visibility is higher.In the condition of opening all windows,the flue gas is removed fastest.The visibility of the bus is restored to a safety level of 5m or more when opening extinguishing system in 25 s later.The different time of opening windows and door have effects on the temperature and the flue gas flow in the bus.The earlier to open windows and door,the higher temperature to reach in the bus,but it would help flue gas remove.The fire location has effects on the temperature,the visibility and the flue gas flow.The temperature near the fire source will rise rapidly when fire appears,and the temperature reaches the highest,the top of the fire reaches 150?.And the visibility fells the fastest,decreased to 1.5m,the flue gas concentration reaches the highest.It is advisable to ensure that the window is closed when bus fire appears and that personnel should be away from the source of fire and escape from the door until the window is opened.