Piecewise-scheduled thrust command control for in-service thrust performance improvement of gas turbine aero-engines: A hybrid fast design approach

Abstract

Gas turbine aero-engines including turbofans, as the dominant powerplant for modern civil aircraft, convert the fossil energy in the jet fuel to propulsive forces via the thermo-dynamic cycle. Unfortunately, thrust regulation capabilities of gas turbine aero-engines are inevitably affected by uncertainties in measurements and gas path degradation during the life cycle, while quantification efforts for these uncertainties by traditional random analysis methods are usually considerable. In this paper, a piecewise-scheduled thrust command controller is proposed based on the improvement of the industrial baseline controller and current measurement levels, aiming at enhancing in-service thrust performance within a tolerable computational burden for engine fleets against these uncertainties. The proposed controller is equipped with a bank of embedded thrust maps for different flight cycle segments, which is fulfilled by a hybrid fast design approach incorporating a random analysis part and an analytical design part, as a new uncertainty quantification method. An industrial baseline controller with the identified thrust mode is also designed as the comparison basis. Simulations are carried out on a validated aero-thermal turbofan engine model with publically accessible uncertainty statistics. Simulation time for constructing the embedded thrust maps of the proposed controller is decreased by 99.8% on a desktop computer, compared to Monte-Carlo approach. Meanwhile, simulation results show that the proposed controller owns a bounded and tight thrust distribution for both new and severely degraded engine fleets at the take-off state within the permitted safety margin of the engine, which mitigates the significant under-thrust consequences from the baseline controller. Hence, the uncertainty control benefits of the proposed controller and its design efficiency are guaranteed.