1D Modelling of Thermal Management of a Jet Trainer Aircraft

Most of current jet aircraft circulate fuel on the airframe to match heat loads with available heat sink. The demands for thermal management in wide range of air vehicle systems are growing rapidly along with the increased mission power, vehicle survivability, flight speeds, and so on. With improved aircraft performance and growth of heat load created by Aircraft Mounted Accessory Drive (AMAD) system and hydraulic system, effectively removing the large amount of heat load on the aircraft is gaining crucial importance. Fuel is becoming heat transfer fluid of choice for aircraft thermal management since it offers improved heat transfer characteristics and offers fewer system penalties than air. In the scope of this paper, an AMESim model is built which includes airframe fuel and hydraulic systems with AMAD gearbox of a jet trainer aircraft. The integrated model will be evaluated for thermal performance. JP-8 fuel is recirculated on the airframe to maintain cooling the oil for AMAD gearbox and the hydraulic fluid for the hydraulic systems. A Fuel/Oil Heat Exchanger (FOHE) is integrated on the airframe main fuel line with a thermally actuated valve located at the fuel outlet port, which prevents fuel temperature from exceeding limitations at the airframe/engine fuel interface. The valve opens at a specified fuel temperature allowing excessive fuel to return to main fuel tank that increase fuel flow through the heat exchanger. AMAD and hydraulic systems also have their own thermal by-pass valves to adjust fluid quantity to be sent to the heat exchanger for cooling.