Model-based design has attracted much attention in the field of aircraft engine control in recent years. As an aircraft engine is a complicated thermomechanical system, it can only be represented by a nonlinear process model. This necessitates the study of the nonlinear control techniques. Based on our recent results, this paper proposes a novel design approach based on a generalized Gronwall-Bellman lemma. Important results are obtained on bounding behavior of the nonlinear states of the engine. The proposed method is easy to design and tune with the appealing feature of enlarging the feasible control envelope. Finally, a simulation study is provided to validate the effectiveness of the control design approach.

It is usual that fuel system of an aero-engine operates within a wide range of temperatures. As a result, this can have effect on both the characteristics and precision of fuel metering unit (FMU), even on the performance and safety of the whole engine. This paper provides theoretical analysis of the effect that fluctuation of fuel temperature has on the controllability of FMU and clarifies the drawbacks of the pure mathematical models considering fuel temperature variation for FMU. Taking the electrohydraulic servovalve-controlled FMU as the numerical study, simulation in AMESim is carried out by thermal hydraulic model under the temperatures ranged from −10 to 60 °C to confirm the effectiveness and precision of the model on the basis of steady-state and dynamic characteristics of FMU. Meanwhile, the FMU testing workbench with temperature adjustment device employing the fuel cooler and heater is established to conduct an experiment of the fuel temperature characteristics. Results show that the experiment matches well with the simulation with a relative error no more than 5% and that 0–50 °C fuel temperature variation produces up to 5.2% decrease in fuel rate. In addition, step response increases with the fuel temperature. Fuel temperature has no virtual impact on the steady-state and dynamic characteristics of FMU under the testing condition in this paper, implying that FMU can operate normally in the given temperature range.

The requirement of fighter's maneuverability puts forward higher indexes for the control performance of aeroengine. It is generally recognized that the proportion integration (PI) control is the most commonly used control method of aeroengine. However, due to the high nonlinearity and performance requirements of aeroengine, the selection of PI parameters needs more accurate methods to satisfy higher performance requirements. In this paper, the linear parameter varying (LPV) model is established according to a nonlinear mathematical model of a turbofan engine. Then, the LPV/PI control based on guardian maps theory is proposed to solve the highly nonlinear aeroengine control problem which improves the response characteristics of aeroengine without changing the control method in the range of the scheduling parameters. In the process of design, a set of controller parameters satisfying the performance requirements is automatically generated by a given initial controller parameter, so designing the controllers at multiple equilibrium points is avoided. Finally, the simulations are performed by the integral separation of PI control at different points in the flight envelope for the nonlinear model. The results illustrate that the control method based on guardian maps theory can contribute significantly to solving the nonlinear problems of aeroengine control system.

Axial force is one of the important factors affecting the life and reliability of centrifugal pumps. Based on the SST turbulence model, the unsteady internal flow field of an aero fuel centrifugal pump under various working conditions was analyzed by using the finite volume method and the axial force of the impeller component was predicted. The position servo force measuring system was used to measure the axial force of the fuel centrifugal pump and the theoretical formula of axial force was modified according to the numerical results and experimental values. The study shows that the pressure distribution of the front and rear pump chambers presented uneven circumferential distribution under the influence of dynamic and static interference through numerical simulation. The simulated head number is basically consistent with the test result and the maximum error of the axial force value obtained by the numerical calculation and the experimental value was 9.7% under different speeds, which verified the accuracy of the numerical simulation. Furthermore, the modified formula can accurately calculate the axial force of the fuel centrifugal pump with an error of less than 9.88%. The results of the study provide a theoretical basis for the calculation and balance of axial force in an aero aero fuel centrifugal pump.

An ultra-high-speed centrifugal pump plays a crucial role as part of an aircraft engine’s fuel supply system. This paper focuses on the coupled vibration and optimization of a parallel double-stage ultra-high-speed centrifugal pump considering fluid–structure interaction (FSI). The accuracy of the numerical calculation is verified and compared with the experimental results. The steady and transient characteristics of the rotor system are analyzed to ensure the operational reliability of the rotor system. Moreover, an orthogonal test is conducted to explore the transient structural characteristics of the rotor system. The existing cross-support structure meets high-speed stability requirements and there is no resonance in the cantilevered rotor system. The maximum and minimum errors for the head of Pump 2 are 4% and 0.7%, respectively. The minimum values for maximum average deformation and maximum average stress are less than 0.31 mm and 245 MPa, respectively, at design conditions. The position of Bearing 1 near the multi-stage impeller has the greatest impact on the deformation and stress of the rotor system, and the deformation and stress increase as the distance increases. The results of this study can provide a valuable reference for the design of ultra-high-speed centrifugal pump rotor systems.

Servo systems are important actuators of aeroengines. The repetitive, reciprocating motion of the servo system leads to significant changes in its time delay and gain characteristics, and degradation increases the uncertainty of these changes. These characteristic variations may have an adverse effect on the dynamic performance of the aeroengine. Therefore, a neural network-based parameter estimation and a multi-loop neural network-based predictive control (ML-NNPC) method for aeroengine inlet guide vane (IGV) servo systems (SVS) were proposed. In this study, the time delay estimation of the servo system was treated as a classification problem, and an SE (squeeze-and-excitation)-GRU (gated recurrent unit) network was proposed to estimate the time delay by using the selected dynamic data of the servo system. The estimated delay was embedded into an online sequential extreme learning machine, and a nonlinear model predictive controller was designed to obtain an optimal control sequence. The compensation control loop was designed to reduce the impact of the model and delay mismatch problems of the control system. The proposed method was applied to the IGV SVS control of a turboshaft engine. The simulation results demonstrate that the time delay is estimated accurately and compensated effectively. Compared to the existing PI and PI with Smith predictor methods, the ML-NNPC method achieves better control performance in the control of both the SVS and the engine rotor speed system. The stability and robustness of the ML-NNPC also show superiority. The results verify the effectiveness of the proposed time delay estimation method and the ML-NNPC method.