Thermal–Hydraulic Modeling and H∞ Control for Aero-Engine Fuel Metering Units

Aero-engines operate across wide flight envelopes and harsh environments, requiring the fuel metering unit (FMU) to perform reliably over a broad temperature range. Fuel temperature fluctuations significantly modify viscosity and density, which in turn alter pressure distribution, flow behavior, and the dynamic response of the metering spool. Based on the first law of thermodynamics and the control volume method, this study theoretically analyzes how these thermal effects influence FMU pressure, flow rate, and spool motion. A thermo-hydraulic FMU model is then developed in AMESim to capture the coupled pressure-flow-motion dynamics. Based on this model, a robust H∞ controller is designed using the mixed-sensitivity approach to compensate for the temperature-dependent degradation in system performance. Simulation results verify that the proposed model accurately reproduces the FMU dynamics under varying thermal conditions. Furthermore, compared with a conventional PI controller, the H∞ controller achieves precise spool displacement regulation over the wide temperature range of −10 °C to 50 °C, effectively mitigating the adverse effects induced by temperature variations.