The Coupling Design And Analysis Of Airframe-Propulsion Integration For Air-breathing Launch Vehicle In Wide Envelope

The air-breathing hypersonic launch vehicle is an important development direction of the future space transportation system.Such vehicle is highly integrated for airframe and engine.The airframe-propulsion integrated design is one of the key technologies.Relative to cruise vehicles,the vehicle has a very wide flight envelope.The coupling of aerodynamics and propulsion is seriously,and it is difficult to achieve integrated performance under high and low speed conditions.Moreover,this kind of vehicle has large scale,and structural deformation brings strong nonlinear fluid-solid coupling phenomenon,which make the problem of airframe-propulsion integration more complex.This paper is based on the background of air-breathing vehicle.The problems of wide envelope,large scale airframe-propulsion integrated design,the coupling of inflow and outflow,fluid-solid coupling,fluid-solid-thermal coupling and fluid-solid-propulsion coupling are studied.The integrated overall design and the analyzed method are established,which can provide technical support for such vehicle.The main contents are as follows:Firstly,for the various problems of coupling and matching in air-breathing vehicle,the design process of airframe-propulsion integration based on multi-opoint and multi-objective optimization in wide envelope are promoted,and the design of the pointed launch vehicle is conducted.The requirements of wide envelope integrated design of airframe and propulsion are analyzed,put forward the evaluated method of performance and construct the design process for the wide envelope vehicle.Develop the multistage integrated design process which contains seven steps in wide envelope.For the fact characteristic of launch vehicle,the main coupling problems are defined.The solution method is put forward aiming at the coupling phenomenon.For the fact demo of a given vehicle,the configuration design and performance analysis are conducted for the integration of airframe and propulsion.Secondly,for the requirements of rapid and precision in the design of airframe-propulsion integration,an efficient internal and external flow coupling method based on CFD and quasi one dimensional flow is proposed.The paper analyzes the complex coupling characteristics of inflow and outflow for integrated configuration.Introduce the method of the isolator core flow and combustor’s heat congestion process,which improves the method of quasi one dimensional flow and can be used to the integrated analysis of the performance for Ma2-8+ dual-mode scramjet engine.The developed method is verified by the comparison with the literature and the results of wind tunnel test of Rocket-base Combined Cycle(RBCC)airframe-propulsion integrated free jet test.Thirdly,for the extreme flight environment of high dynamic pressure and high temperature on the inlet’s compression surface,the method of fluid-solid-thermal coupling analyzed method is established,and the nonlinear fluid-solid-thermal coupling problem of inlet’s plate is studied.The plate’s two-way fluid-solid-thermal analysis method is improved,which is derived from Von Karman large deflection plate theory and two order piston theory.The paper studies the stability boundary which is influenced by aerodynamic damping and the aspect ratio under the free flow condition,and analyzes the nonlinear fluid-solid and fluid-solid-thermal coupling phenomenon and mechanism at different Mach numbers.The results show that the ratio of length to width is an important factor affecting the stability of the fluid-solid coupling,and the time effect of fluid-solid-thermal coupling for plate is obviously.Fourthly,for the complicated shock waves around the inlet’s lip,the method of fluid-solid coupling analysis for rigid element with elastic axis is extablished.The nonlinear fluid-solid coupling problem is studied for variable tip of inlet.In view of the complex flow phenomenon of inlet’s tip,the fluid-solid coupling motion equation of inlet’s tip is derived based on Hamilton principle and two order piston theory,and the nonlinear fluid-solid coupling phenomenon under the influence of different parameters is studied based on such equation.The influence of tip’s nonlinear fluid-solid coupling phenomenon by different nonlinear stiffness and Mach number is obtained,and compared the coupling relationships of different kinetic parameters and fluid-solid interaction.Fifthly,put forward the geometrical nonlinear structural dynamics reduction strategy based on the proper orthogonal decomposition(POD).The fluid-solid-propulsion coupling analysis method is developed based on the application of POD in the rapid prediction of the flow.Such method is used to this paper’s object.The influence of the structural vibration on the performance of the inlet and the influence of the fluid-solid coupling on the integral performance are obtained.