Study On Function Of Oxygen Evolution And Fuel Tank Thermal Model Technology

The research derives from fuel tank flammability assessment method for commercial aircraftairworthiness certification. On the basis of whether the Onboard Inert Gas Generation System(OBIGGS) works or not, the Flammability Exposure Evaluation Time (FEET) is divided intoflammability time and autoignition time. The oxygen evoluting from fuel and change rules of fueltemperature are discussed. Through doing the research, the design of onboard inerting system and fueltank flammability assessment can be guided. the text buildOn studying oxygen evolution from fuel, the equilibrium model based on conservation of mass isbuilt, and unequilibrium model from FAA is introduced. The equilibrium model demonstrates thatthe velocity of oxygen evolution from fuel is equal to the velocity of oxygen dissolved into fuel, andthe unequilibrium model demonstrates that the velocity of oxygen evolution from fuel is not equal tothe velocity of oxygen dissolved into fuel and the velocity can be described by time constant. Theresearch results show that two of the velocities are basically equal in flight envelope except forcruise phase. The reason is that the equilibrium model can not consider the effect of supersaturationstate and the unequilibrium model is lack of the corresponding theoretical basis. Because of thefaults of the two models, the theory of two-film theory and molecular mass transfer is used to buildunequilibrium model, and the results show that the difference of equilibrium model in cruise phase issolved.On studying the fuel temperature along the flight time, the fuel tank thermal model based on thefuel tank structure of new vortex slurry regional aircraft is built. The equations of each node based onconservation of energy are built, and the temperatures on both wing fuel tank and body fuel tank arecalculated. The research results show that there are great temperature differences between the wingfuel tank and body fuel tank; when evaluating fuel tank flammability, the wing fuel tank and body fueltank must be calculated respectively.