The rule of mass diffusion of CO2in jet fuel is an important consideration in the research of the aircraft fuel tank inerting system.A pressure-decay test apparatus was constructed to measure the diffusion coef-ficient of carbon dioxide in RP-3 jet fuel by monitoring the pressure variation at constant temperature of -20,0, 20,40,and 60℃,respectively.The two-dimensional diffusion equation in the hermetic container was derived based on Fick's law, and the concentration distribution was determined via the numerical method with the assumption that diffusion coefficient was known.Then pressure on ullage was predicted by utilizing mass conser-vation and real gas state equation and the calculating result was compared with the experimental data.By adop-ting the diffusion coefficient as the independent variable,the error functions as the experimental and theoretical data were derived.The optimum solution to the diffusion coefficient was obtained by Husain single variable search method to minimize the error.The study also reveals that the diffusion coefficient increases with the rise of the temperature,and the Arrhenius equation could be employed to correlate the diffusion coefficient and tem-perature.%CO2在航空燃油中的质量扩散规律对飞机油箱惰化系统的研究极其重要.搭建压力降法实验装置测量CO2在RP-3航空燃油中的扩散系数,实验测试了-20、0、20、40和60℃恒温条件下的CO2气相空间压力随时间变化关系.根据Fick定律建立了容器中二维扩散方程,并采用数值解法,设定扩散系数值,求解气体在航空燃油中的浓度分布,根据质量守恒和实际气体状态方程可得到CO2气相空间压力,并与实验记录的气体压力进行比较.以扩散系数为自变量,推导了实验与理论计算误差函数,并采用Husain单一变量搜索法,使误差函数值最小,可得到扩散系数最优解.研究还显示CO2在RP-3航空燃油中的扩散系数随温度升高而增大,满足Arrhenius方程.
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