Research On Airframe/Propulsion Integration Control With Active Cooled Scramjet Engine

Since the concept of hypersonic was proposed,the airbreathing hypersonic vehicle powered by ramjet engine has been an important research field in aerospace.After more than half a century of development,the airbreathing hypersonic vehicle still faces many key technical problems.These problems include the control of active cooling scramjet and the integrated flight/push control.The essence of integrated design of hypersonic vehicle determines the need for integrated control.Meanwhile,active cooling scramjet provides the possibility for long-time cruise of hypersonic vehicle.The main research content of this project is obtained by combining the two,namely,integrated flight/push control considering active cooling.Most of the previous integrated control literature considers the non-cooled scramjet.In this paper,a one dimensional active cooled scramjet model is used to study the integrated flight/push control.Focus on the engine overtemperature and unstart problem control research.Firstly,An integrated model of hypersonic vehicle/actively cooled scramjet was established.The model requirement of integrated control is analyzed and the model used in this paper is given.The characteristics of aircraft model and engine model are analyzed.The inlet stability margin characteristics and cooling oil temperature characteristics of actively cooled scramjet are obtained.The flight/push coupling mechanism is analyzed,and the flight/push integration model is established by connecting the aircraft model and the engine model.Secondly,the coupling characteristics between hypersonic vehicle and actively cooled scramjet are analyzed.The interaction between the attitude of aircraft and the working state of engine is discussed.The influence of coupling characteristics on engine performance is analyzed.The influence of coupling characteristics on engine safety is analyzed.The effects of coupling characteristics on inlet stability margin and cooling channel oil temperature are included.Thirdly,the overtemperature problem of actively cooled scramjet is studied from the perspective of flight/push integration,especially the problem of "faster and faster" caused by overtemperature.Two solutions are verified by simulation.One is to adjust the fuel supply strategy of the engine,that is,the fuel dump scheme.The other is to change the flight path,that is,to achieve the thrust drag balance scheme at low altitude.The possibility of reducing aerodynamic thermal load by changing flight path is discussed.The results show that changing flight trajectory has little effect on aerodynamic thermal load Therefore,the overtemperature problem can not be solved by changing flight path to reduce aerodynamic thermal load.Although changing flight trajectory cannot effectively reduce aerodynamic and thermal load,it can achieve push-drag balance at low altitude by reducing altitude and increasing drag,and also solve the problem of "faster and faster" of aircraft.Finally,the simulation and analysis of hypersonic vehicle/actively cooled scramjet integrated control are carried out.The LQR controller is designed and the flight/push integrated control loop is designed.By comparing with the scramjet without cooling,the necessity of considering active cooling in the integrated control and the particularity brought by active cooling for the integrated control are obtained.At last,the simulation analysis of inlet margin protection and thrust switch control under low Ma and over temperature protection and thrust switch control under high Ma are carried out.The results show that the controller has good control effect and the integrated control loop and control scheme are designed reasonably.