Research On Component Level Modeling And Startup Control Of Turbofan Engine

Aeroengine control system is the premise to ensure the safety and stability for the whole flight envelope.As performance requirements for propulsion systems continue to increase,it is becoming more and more difficult to develop reliable and stable control systems,while using component-level model of aeroengine combined with the rapid prototyping technology in the design and verification of control system can improve the system development efficiency and reduce the cost.This paper focuses on the design and verification of control system,and the main contents include component-level startup modeling,model modification of startup process and above-idle state of aeroengine on ground situation,the development and verification of digital simulation platform and rapid prototyping platform.Firstly,the development trend of aero-engine modeling and its control technology are described,and the development status of aeroengine start-up modeling,component-level model modification and the implementation of software and hardware in engine control system design are summarized.Secondly,the techniques and methods of modeling above idle state are analyzed on the NASA's JT9 D high bypass ratio turbofan engine.Its ground-start component-level model is established with the methods of component characteristics extrapolation,modeling of cold-rotation state,modeling of starter and improved solution algorithm based on the analysis above.The comparison between simulation results and test data released by the International Civil Aviation Organization(ICAO)shows that the maximum relative error is less than 7%,The effectiveness and accuracy of the modeling method are thus verified.Thirdly,according to the JT9 D ground starting model established in the previous chapter,the modification of startup model by the adjustment of efficiency in combustion chamber,the component coefficient of total pressure recovery,the model of rotor resistance and the component characteristic modification are investigated in this part,by comparing with the test data,the maximum simulation error of the starting process is reduced from 7% to 5%.To the above-idle engine model,this paper starts with the optimization algorithm,component characteristics optimization factors and optimization objectives are structured and genetic algorithm is used to iteratively solve the best optimization coefficients.The maximum relative error of simulation results is within 1%,and this shows that using different modification technologies for different work stages can further improve the simulation accuracy of the component-level model.Finally,the software and hardware design of the control system is researched in this paper,which includes optimal design of starting control,the establishment of internet-based multi-user collaborative digital simulation platform and the development of control system rapid prototyping simulation platform.The modified JT9 D engine is integrated to these two platforms with the application of C-code generation technology,and the specific optimization simulation of startup control law is simulated in them.The comparison between the simulation results of these two platforms fully verifies the effectiveness of the startup control law.