Development and Validation of a Civil Aircraft Engine Simulation Model for Advanced Controller Design

This thesis is concerned with the results of a joint academic and industrial study on the development of a detailed nonlinear dynamic model of a turbofan jet engine to be used for research into advanced control strategies for civil turbofan aircraft engines. The model is representative of a dual shaft engine with variable bleed, variable stator vanes, turbine cooling, heat transfer, and a duct and exhaust nozzle. A switched, gain-scheduled, feedback control system incorporating bumpless transfer and antiwindup functionality has been designed and implemented according to current industrial practice. This baseline implementation permits realistic transient operation of the simulation and may act as a reference design for further control work. The simulation computes a non-iterative solution, by progressing calculations in the direction of the gas stream flow. Where possible the underlying physics are used and empirical approximations are avoided so that the model requires minimum data. This approach also makes a future inclusion of component failure easier to implement. The simulation is modular in nature so that engine or control modules can be easily replaced or modified if an improved design becomes available. The Simulink implementation of the control architecture has been redesigned to permit the addition or removal of control loops, also during the simulation’s operation, to allow testing of advanced control strategies. The entire controller can also be easily replaced. A detailed description of the modeling process, the various simulation issues that arise with a model of this complexity, and the results of the overall aero-engine system are presented. The design of the switched, gain-scheduled aero-engine controller with bumpless transfer and antiwindup which achieves dynamic performance that closely matches that of a real aero-engine is also discussed.