Research And Simulation Of Variable Cycle Engine Control Technology

At present,variable cycle engine is one of the most promising research directions of aircraft engines.It can meet the needs of the aircraft,especially military fighters,under different missions.It can also meet the performance requirements of high unit thrust and low fuel consumption.In this paper,a component-level mathematical model of variable cycle engine with core drive fan stage is constructed and the main control law research work is carried out by the engine.The specific research work is as follows:Firstly,by analyzing the mathematical models of various components of the engine,the steady state and dynamic models of the variable cycle engine with core driven fan stage are established by Matlab/Simulink software.The angles of the guide vanes and the relevant guide components are considered in the modeling process.The two operating modes of the variable cycle engine are single bypass mode and double bypass mode.Through the simulation,the switching process between the two modes of the variable cycle engine and the related characteristics of the engine which comes with the variable cycle technology is analyzed.The linearize state space model of the steady state operating point of the engine is established with one step least squares method.Secondly,by using the research method of the conventional turbofan engine control system on the variable cycle engine component-level model,the control system simulation platform of the variable cycle engine is built,and the main control law of the variable cycle engine is designed and verified by simulation.Under the proposed control law,the variable cycle engine can run quickly and stably from the idle state to the maximum state.Among them,the main control law is the main fuel control law,including the steady state point controller,the limit protection control module based on the linear controller and Min-Max selector.The connection rules of different output limits and Min-Max selector are analyzed.The Ndot acceleration control plan and the corresponding acceleration/deceleration controller are designed by the improved variable replacement method.Finally,the variable cycle engine control method based on sliding mode control is studied,which mainly includes two control methods of variable cycle engine limit protection controller and sliding mode multivariable controller based on a single variable sliding mode controller.The advantages of the limit protection controller based on the sliding mode limiter compared with the traditional linear controller are verified by simulation,which avoids the conservativeness brought by the traditional linear controller.At the same time,the improved controller in this paper avoids the defect that the augmented state of the engine needs to be given beforehand when the main controller uses the sliding mode controller.The application of sliding mode multivariable controller in variable cycle engine is also studied preliminaries in this paper.By combining sliding mode multivariable controller with Min-Max selector,the combination of multivariable controller and limit protection controller is realized.The effectiveness and robustness of the control logic in terms of output limit protection are verified by simulation.