Research On Modeling And Control Of Co-axial Turbine-based Combined Cycle Engine

Turbine-based combined cycle(TBCC)propulsion system is considered to be the best choice for the first stage power of the two-stage-to-orbit vehicle and to be the main development direction of the next generation of air-breathing engines,because of its wide working envelope and excellent performance.The main work of this dissertation was to establish the numerical model of the co-axial TBCC propulsion system,and analyze its operation performance at different working modes,including:Firstly,the integrated numerical model of the inlet/TBCC engine was established.The co-working relation between components was established using balance equation.The method to get the numerical solution of the nonlinear equations was researched,and the hybrid Newton-inverse Broyden method was proposed to solve the co-working equations of components,which could ensure the accuracy of the solution and reduce the computational complexity.Secondly,the startup problem of TBCC at turbine mode was studied,including ground startup,windmill startup and air static startup.Based on the geometric similarity theory,the expansion parts of the engine characteristics were gotten.The flow continuity condition between components was established using balance method.The engine startup simulation is carried out.Thirdly,the working characteristics of TBCC engine were analyzed.According to the fuel consumption rate comparison between the ramjet mode and the turbine mode,the mode transition working point of the combined engine was determined.At the same time,according to the requirements of conversion,the control plan for the transition mode was made to guarantee the smooth transition between the different working modes of the combined engine.Finally,the controller design problems of TBCC engines were studied.According to its working mode,the controllers were preliminarily divided into five types: startup,dry,wet,ramjet and transition.The augmented linear quadratic control algorithm was adopted and its weight matrices Q and R were optimized base on the differential evolution algorithm,and the controller met the control target.The proportional integral controller was used to control the startup process and the ignition of afterburner.The feasibility of these control methods are valid by simulations.