On Modelling a Fighter Aircraft Fuel System as a Heat Sink

Abstract: This thesis presents a simulation study on the thermal performance of the fuel systemin a fighter aircraft. The main objective is to investigate the potential utilization of thefuel system as a heat sink and explore various operational aspects that can enhance itsperformance. To achieve this, the study focuses on analyzing the impact of tank emptyingsequences, fuel types, and the implementation of bypass recirculation under low thrustconditions.The fuel system is modeled using the Modelica language-based tool, Modelon Impact,which enables a thorough and detailed examination of its thermal behavior. A functionalmodel of the fuel system has been successfully built in this modeling tool. The investiga-tion of the three operational aspects has been divided into two heat sink studies. Heat sinkstudy 1 examines the tank emptying sequences, with three different sequences being inves-tigated. The simulation results did not demonstrate any clear and significant benefits fromusing different emptying sequences. However, emptying the fuselage tank first showedslightly better behavior compared to the sequence that involved emptying the wing tanksfirst. Heat sink study 2 focuses on the implementation of bypass recirculation of the fuelback to the tanks. The primary objective of heat sink study 2 is to maintain the feed linetemperature close to the threshold determined by the fuel type in order to . The simulationresults revealed significant improvements in the heat sink capacity of the system, reachingup to 168%.