Study On Characteristic Simulation And Semi-physical Test Of Digital Control Fuel Metering Unit

The research on fuel metering unit(FMU) plays an important role in the development of the aero-engine control system, and characteristic simulation of which can help to shorten the developing period. Semi-physical test has became main reference to the engine bench test and the performance optimization of FMU. At present, as digital control regulators substitute for traditional mechanical hydraulic ones in most cases, semi-physical tests for these regulators represented by the digital control FMU, have more and more urgent engineering requirements.In this thesis, an object-oriented model was established for a digital control FMU, and then its characteristic simulation and semi-physical test were carried out. Firstly, AMESim and MATLAB/Simulink were used to build the model of hydraulic components and the stepping motor respectively. An interface was designed for data exchange between these two models, which makes an effective FMU AMESim/MATLAB co-model and provides a favorable access to study its characteristics. Secondly, MATLAB/Simulink software was used to build a simplified component-level model of a turbo-shaft engine. By combining the FMU model with the engine model, full digital simulation on the aero-engine with FMU were fulfilled. Finally, semi-physical testing has been done after some reformation on the existing test-bed and some key parameters in model were modified or optimized.Results show that the error of metered fuel flow rate between the co-model presented in this thesis and the reference data of the FMU is limited to 6%. The co-model has higher steady precision and can describe the actual dynamic properties of the unit. The simplified component-level engine model has satisfactory steady-state precision and can describe dynamic property of the engine as well, whose performance indicators well match with the parameters of the FMU. Comparison between the simulation and the testing data show that the steady-state error is 8.8% at most. Besides, the study on the FMU characteristic simulation and its semi-physical experiment is beneficial to the development aero-engine control systems.