Aircraft Fuel Thermal Management System and Flight Thermal Endurance

Abstract

An aircraft thermal management model was created in which fuel is circulated through the heat dissipating components for cooling purposes. A fraction of this fuel is then fed to the engine for combustion, while the excess is cooled by rejecting heat to the ambient and returned to the tank. The thermal management system was designed with the intent of controlling the heat dissipating surface temperature, ensuring a certain heat removal rate, while safeguarding the physical integrity of the fuel. The time variation of the fuel temperature and heat transfer rates was calculated. It was observed that for a constant heat dissipating surface temperature, the heated fuel temperature increased, and the heat removal capacity degraded over time. Conversely, for a specified heat removal rate, both the heat dissipating surface temperature and heated fuel temperature increased during the flight. Lastly, when the maximum fuel temperature was specified, both the heat dissipating surface temperature and heat removal rate decreased over time. In all cases, the time taken for these variables to hit the user-defined threshold values was recorded. A detailed sensitivity analysis was also presented highlighting the critical importance of the fuel recirculation rate on the performance of the thermal management system.