飞机货舱轰燃规律的试验研究

Experimental study on flashover law of aircraft cargo compartment

为研究飞机货舱火灾发展至轰燃的内在规律,在1/4体积标准飞机货舱内开展了一系列火灾轰燃试验。以单壁瓦楞纸箱被引燃作为轰燃发生的判据,研究了油盘尺寸和燃料种类对轰燃的影响,通过对货舱上部热烟气层平均温度、地板所受辐射热通量、燃料热释放速率及烟气体积分数的分析,探讨了轰燃发生的临界条件和表现形式。结果表明:油盘尺寸的增大提高了轰燃发生的可能性和轰燃的剧烈程度,在达到引发轰燃所需的临界油盘尺寸后,继续增大油盘尺寸会使轰燃发生的时间提前;引发飞机货舱轰燃所需的临界条件为,上部热烟气层平均温度达到456℃,地板所受辐射热通量达到14.3 kW/m2;此外,通过对轰燃所需的临界油盘尺寸与燃料热物性参数的拟合,发现轰燃所需的临界油盘尺寸正比于燃料的蒸发热,反比于燃料的燃烧热。

Aircraft cargo compartment fire has always been one of the most important factors affecting flight safety.Due to the large fire load,many types of combustibles,and poor ventilation conditions in the aircraft cargo compartment,once a fire occurs,the combustible smoke can quickly accumulate on the top and develop to flashover in a short time,which will seriously affect the life and property safety of passengers.To study the inherent law of the development of aircraft cargo compartment fire to flashover,a flashover experimental platform conforming to the Federal Aviation Administration cargo compartment fire experimental standard was built.Taking the ignition of the single-walled corrugated boxes as the criterion of flashover,the effects of different oil pan sizes and different fuel types on flashover were studied.The average temperature of the hot smoke layer in the upper part of the cargo compartment,the radiant heat flux received by the floor,the mass loss rate of fuel and the smoke volume fraction were measured,and the critical conditions and manifestations of flashover were analyzed.The results revealed that the increase of the oil pan size would increase the average temperature of the hot smoke layer,the radiant heat flux received by the floor,and the heat release rate of the fuel,which increased the possibility of flashover and the severity of flashover.After reaching the critical oil pan size required to initiate flashover,continuing to increase the size of the oil pan will advance the time of flashover.In the cases of this experiment,the critical value of the average temperature of the upper hot smoke layer required to initiate flashover is 456℃,and the critical value of the radiant heat flux received by the floor is 14.3 kW/m~2.In addition,by fitting the critical oil pan size required for flashover with the thermophysical parameters of the fuel,it is found that the critical oil pan size required for flashover is directly proportional to the evaporation heat of the fuel and inversely proportional to the combustion heat of the fuel.