Research On The Modeling And The Control Method Of The Three Ducts Variable Cycle Propulsion System

With the rapid development of the aviation industry,the traditional turbo engine now has been difficult to meet the dual performance indicators of high thrust and low fuel consumption.For this reason,the concept of variable cycle engine has been put forward.It not only improves the operational performance of Air Force fighter,but also applies supersonic flight for future intercontinental supersonic airliner.And now,the foreign researchers are developing the third duct adaptive engines.Based on the above considerations,this article through study the variable cycle engine and adjustable component characteristics.The research object is three ducts variable cycle engine.On the basis of it,the three ducts variable cycle engine and supersonic inlet integration model is established.The mathematical model,the installation of variable cycle performace,control law and performance optimization are carried out.The main arrangements are as follows:First of all,the article studies the three ducts variable cycle engine based on double bypass variable cycle engine.The integrated model of variable cycle engine and supersonic inlet is established.In the process of modeling,the characteristics of variable cycle adjustable components are studied and the effects of mode select valve on the third duct flow and total pressure loss are also considered.Meanwhile,the paper studied the flow characteristics of the inlet and analyzed the influence of variable cycle engine structure of spillage drag,aft body drag and thrust installation.The results show that when the Mach number is greater than 1,the drag of three ducts variable cycle engine is reduced by 20%compared with the mixed exhaust turbofan engine.Secondly,the article studies the installation performance control of three ducts variable cycle engine.The constant flow control is studied and simulated on the ground.In subsonic and supersonic cruise,the constant flow control is applied and the installation performance is compared with the mixed cycle variable cycle engine.The results show that compared with the mixed exhaust three ducts variable cycle engine,the inlet spillage drag of the separate exhaust variable cycle engine is reduced by about18%.Under the constant flow control,the inlet spillage drag decreases more obviously.The design of aeroengine robust controller is an indispensable part of the variable cycle engine.An off-line identification medthod based on nonlinear least squares identification is applied in the engine.Under the environment of Matlab Simulink environment,the controller procedures is established by using augmented LQR and H_?engine controller.And the corresponding simulation research has been done.The design of multi mode controller has been carried out,which chose supersonic and subsonic cruise points for simulation and verfication.Also the transition state regulation scheme of variable cycle engine has been studied.The results show that the flight control requirements are met and the engine can achieve stable switching.Finally,the charpter studied the performance optimization control of the three ducts variable cycle engine.It mainly includes the maximum thrust,the minimum fuel consumption rate and the lowest turbine temperature optimized models,which uses SQP algorithm for performance optimization control.The simulation results show that the algorithm can obtain the optimal operating conditions of variable cycle engine in different working conditions and achieve steady state optimization control of engine.