| Since its invention,ramjet has been widely used in the field of supersonic all over the world,with the advantages of high specific impulse,simple structure and high economy.Ramjet plays an important role in the field of national defense and military in the world,especially in Europe and the United States and other military powers have been committed to the research of ramjet technology.With the development of the working range and the longer flight distance of ramjet,the ramjet which only considers the fuel adjustable single variable control can not adapt to the new environment and new operational requirements.In this paper,aiming at the problems faced by the fixed geometry structure ramjet,considering the introduction of geometrically adjustable structure,the control law and multivariable control method of geometrically adjustable ramjet are studied from the perspective of control,and the hardware in the loop simulation test platform is used to verify the multivariable control system and control law of geometrically adjustable ramjet.Firstly,a control oriented geometrically adjustable ramjet model is established.Compared with the fixed geometry ramjet,the variable specific heat of ramjet is considered,and the ramjet model with adjustable fuel equivalent ratio,adjustable inlet throat area ratio and adjustable nozzle throat area ratio is established by using the idea of component level modeling.At the same time,the safety margin and thrust performance of the engine are defined in the model,which are introduced into the subsequent research of ramjet MIMO control.Secondly,the characteristics and regulation rules of geometric adjustable ramjet are studied.The influence of fuel equivalent ratio,inlet throat area ratio and nozzle throat area ratio on engine thrust and intake margin are analyzed in the engine safety boundary.The characteristic variation curve and dynamic response curve of actuator are obtained.The benefit analysis of ramjet with adjustable throat area ratio and geometric adjustable throat area ratio is carried out.The simulation results show that the introduction of geometric adjustable structure can improve the thrust and the margin of the inlet.The regulation law and safety boundary of the multi variable joint action are analyzed and studied.The running curve of the engine under the action of multi variable is obtained.The maximum thrust operation law and the fuel saving operation law under the multi variable are proposed.The verification is obtained in the open-loop control,which provides the basis for the research of the multivariable closedloop control of the ramjet.Thirdly,the research on the multi variable control of geometric adjustable ramjet is carried out.The linear model of state variable is used to describe the geometric adjustable ramjet,and the engine model is identified systematically.The state space expression of MIMO ramjet is obtained.Aiming at the thrust control and stability margin control of engine,the two in two out and three in two out multivariable controllers are designed based on the hybrid sensitivity H ∞ control method.The system performa nce analysis and robustness analysis are carried out for the multivariable controllers.Through the analysis,the MIMO controllers meet the design requirements.The multi variable control system of ram engine with two in two out and three in two out is des igned.The multi variable control law of engine is analyzed under different Mach number conditions.The simulation results show that the MIMO control system can track the thrust and margin control commands better.The design and Simulation of the work task of the ramjet show that the control effect of MIMO system can meet the requirements of the engine work task in a wide range.Finally,the hardware in the loop simulation of geometrically adjustable ramjet multivariable control is carried out.Based on the test platform of Ni veristand and digital simulation software co simulation,the hardware in the loop simulation test scheme of geometrically adjustable ramjet is designed,the software and hardware resources of the simulation platform are configured,and the software environment and hardware experimental platform for simulation test are built.Then,in the hardware in the loop simulation test platform,the effect and control law of two in two out and three in two out ramjet multivariable controllers are s imulated and verified.The experimental results show that the multivariable controller has good control effect under different Mach number conditions,and the MIMO control system can achieve equal thrust control and equal inlet margin control. |
