Research On Civil High Bypass-ratio Turbofan Engine Modeling And Control

In recent years, the concern in the field of aero-engine development in domestic is warming up, especially in civil high bypass ratio turbofan engine for the large aircraft project. As a kind of high cost, high risk industrial products, a high precise simulation model is of great practical value for the development of aero engine. Therefore, this paper studies the civil high bypass ratio turbofan engine modeling and control methods.Firstly, in this paper, the civil high bypass ratio turbofan engine nonlinear component level model was established for CFM56-5A. The effects of high bypass ratio on the fan was considered, and the inner and bypass of the fan were modeled separately. The co-working equations of components were studied. The model of the guide vane and the model of the thrust reverser were established. The simulation includes the acceleration and deceleration dynamic process above idle, and full process transition from ground to cruise. The simulations show a preliminary validation of the established model, and laid a good foundation for further study of control algorithm.Secondly, a new method of adaptive PID control was studied for aero-engine. A new algorithm of extreme learning machine(ELM) was proposed to by improved firefly algorithm, which could predict the output of the engine model. The size of the ELM network was reduced by this algorithm, its generalizing ability was enhanced under the premise of guaranteeing the accuracy. Based on the prediction model, the control parameters of PID were adjusted according to the working condition of the engine. Compared with the conventional PID control, the adaptive ability to parameter variation of the control system was improved.Finally, the high performance control of aero-engine was studied inthis paper. It included the study of performance degradation mitigation control and performance seeking control of aero engine. The thrust estimator for feedback was designed based on the steady-state mapping, dynamic correction, the degradation compensation. The inner loop H2/H?fan speed controller and the outer loop PI thrust controller were designed. The simulation verifies the control effect under performance degradation. Performance seeking control system was built based on adaptive differential evolution algorithm. The adaptive scaling factor was proposed using Sigmoid function to improve the optimizing ability of the algorithm. The simulation results show that the method can increase the thrust and decrease the specific fuel consumption.