Research on Calculation Method of Fuel Temperature According to Airworthiness Regulations

How to establish a general fuel tank thermodynamic model that meets the requirements of airworthiness certification and how to obtain the equilibrium temperature difference △T and time constant τ in the Monte Carlo evaluation model after obtaining the fuel temperature change law within specific flight envelope are the bottleneck issues need to be solved urgently in the airworthiness certification process of fuel tank flammability. This paper builds the fuel temperature simulation calculation model on the MATLAB/Simulink software platform to obtain the fuel temperature change law and obtains the high-order functional expression of the fuel temperature change law in each stage by means of MATLAB polynomial piecewise fitting function. The exponential attenuation equation stipulated in the Monte Carlo evaluation model is used to characterize the change law of fuel temperature. Among which the total ambient temperature (TAT) is obtained by the method specified in the evaluation model, and the equilibrium temperature difference and time constant are obtained by the improved genetic algorithm. The equilibrium temperature difference and time constant obtained by the inversion are input into Monte Carlo model for calculation, the calculated temperature data and the actual measured flight data are compared to verify the reliability of the method.