Study On The Effect Of Oxygen Concentration In Low Pressure Environment On Flash Point Of Aviation Kerosene

With the rapid development of economy,air traveling has become the first choice for business trip as well as leisure trips.In recent years,several aircraft fire accidents have occurred and the major casualties caused by accidents have a great impact on the public.The safety of aircraft flying at high altitude has caught the attention of the society.As an important part of aircraft safety,the aircraft fuel tank system has been widely studied in fire prevention and control research.To study the effect of oxygen concentration in low-pressure environment on flash point of aviation kerosene,this paper mainly does the following work:Firstly,the variation rules of oxygen concentration in the fuel tank of high-altitude flight are analyzed.The calculation models of oxygen solubility and oxygen efflux in the fuel tank are established based on the empirical formula.Referring to the FAA rules and published literatures,the range of oxygen concentration in the fuel tank is determined when the aircraft is flying at high altitude;Secondly,based on the Clausius-Clapeyron relational formula,the calculation model of flammable liquid flash point under normal pressure environment is established.From previous model,the calculation model of flammable liquid flash point in low pressure environment is derived,which provides the relationship between the flash point and the pressure;Further,experiences measure the variation of the flash point of aviation kerosene under different pressures in the range of 0~11000m above sea level.In the experiences,the vacuum pump is used to simulate the low-pressure environment.The impact of different oxygen concentrations on the flash point of aviation kerosene is simulated by injecting oxygen into the low-pressure chamber;Finally,by analyzing the experimental data,the variation rules of aviation kerosene flash point under different environmental pressures and different oxygen concentrations were observed.The fitting formulas of different environmental pressure/different oxygen concentration and aviation kerosene flash point were established.The experimental results show that the fitting formula of environmental pressure and aviation kerosene flash point can accurate describe the model of flash point in low pressure environment.The logarithm of environmental pressure is linearly related to the reciprocal of aviation kerosene flash point.Aviation kerosene flash point and oxygen concentration index has negative linear correlation.As the altitude increases,the environmental pressure becomes smaller and the oxygen concentration increases.Thus,the flash point of aviation kerosene will decrease and the aviation kerosene fire hazard level beyond the original level to a more dangerous level.