Modellering av ett bränslesystem i Modelica
tillämpat på ett obemannat flygplan
Mathematical models possible to simulate are of great importance in order to make successful projects in the aircraft manufacturing industry. An aircraft fuel system is very complex, containing pipes, tanks, orifices, valves and pumps. The principal of this thesis is using the tool Easy5, which no longer is considered reliable enough in terms of development and support. This thesis tries to evaluate the Modelica language as a possible alternative to Easy5. To make this evaluation, the components concerned in the fuel library in Easy5 are implemented to the Modelica language. Small hydraulic systems are built up in Dymola, and verified against Easy5 through simulation with high accuracy.A model of the fuel system of an unmanned aerial vehicle (UAV) is built from the implemented Modelica components to examine how Dymola manage a large model. The simulation made in Dymola was considerably more time efficient than the one made in Easy5, in the range of minutes instead of hours. Thus, much time can be saved if Dymola is used instead of Easy5.Finally, the components in the fuel library handle a two phase flow of fuel and air. Modeling a two phase flow is not trivial and discontinuous mass flow and pressure values are also implemented and discussed.