In order to study the fuel temperature change rule during flight

a thermal network method was adopted to establish a thermal model of the fuel tank

and the boundary conditions corresponding to the flight experiment were input into Matlab/Simulink software platform to verify the credibility of the model. Based on that

the change rule of fuel temperature in each tank compartment throughout the voyage was analyzed. Results showed that the calculation method and simulation model had high credibility; when the error between the experimental value and the calculated value exceeded 1.67 K

the simulated temperature was higher than the experimental temperature. The fuel temperature in the fuselage tank was high in most sections

representing the flammability exposure time level of the entire fuel tank system as the focus of attention for airworthiness compliance certification. Taking the cruise end stage as an example

the fuel temperature of the fuselage tank was 25 K higher than the wing tank fuel temperature on the standard long-range flight

the average temperature was 7 K higher on the fuselage tank fuel temperature than the wing tank

the hot day was shorter during the voyage

and the fuel temperature of the fuselage tank was 12 K higher than that of the wing tank. The fuel temperature of the wing fuel tank rebounded greatly during the descent phase of the aircraft

and its flammability exposure time was mainly concentrated at the end of the voyage.