符合适航认证要求的燃油温度计算方法

Calculation method of fuel temperature conforming to requirements of airworthiness certification

基于适航认证需要,以某型飞机中央翼油箱隔舱在规定工况下实测的燃油温度变化曲线为输入条件,借助于MATLAB多项式分段拟合功能,获取了各个阶段燃油温度变化规律的高阶函数表达式;采用Monte Carlo评估模型中规定的指数衰减方程来表征燃油温度变化规律,其中环境总温(TAT)由评估模型中所指定方法获取,平衡温差和时间常数由改进后的遗传算法反演得出;将反演得到的平衡温差和时间常数输入Monte Carlo评估模型并开展计算,比较了计算所获的温度数据与实测的多项式拟合数据,结果表明:两者变化趋势完全一致,各时刻的温差均不超过1.67 K,整个航段燃油温度的计算值和实测值平均差约为0.0501 K;且在误差值较大的阶段,程序计算值均高于飞行实测值,满足适航标准的相关要求。所提出的时间常数和平衡温差反演方法科学可信,它较好地解决了当前适航认证中的瓶颈问题,可有力地支撑大飞机适航认证工作的顺利开展。

Based on the requirements of airworthiness certification,the measured fuel temperature change curve of the central wing fuel tank compartment of a certain aircraft under specified working conditions was taken as the input,and the high-order functional expression of the fuel temperature change rule in each stage was obtained by means of MATLAB polynomial piecewise fitting function.The exponential attenuation equation stipulated in the Monte Carlo evaluation model was used to characterize the change law of fuel temperature.The total ambient temperature(TAT)was obtained by the method specified in the evaluation model,and the equilibrium temperature difference and time constant were obtained by the improved genetic algorithm. The equilibrium temperature difference and time constant obtained by the inversion were then input into Monte Carlo evaluation model for calculation, the calculated temperature data and the measured polynomial data were compared. The results showed that both trends were exactly the same,the temperature difference between each moment did not exceed 1.67 K,the mean difference between the calculated value and the measured value of fuel temperature during the entire flight segment was about 0.050 1 K;in the stage with large error value,the value calculated by program was higher than the value measured by flight,which met the relevant requirements of airworthiness standards.The inversion method of time constant and equilibrium temperature difference is scientific and reliable,which can solve the bottleneck problem in airworthiness certification process and can effectively support the smooth development of airworthiness certification of large aircraft.