Research On The Modeling Of Aero-engine Start-up Process And Control Law Optimization

At the stage of engine design and performance optimization,it is a consensus both at home and abroad to use aero-engine start-up models to study the starting performance,with the purpose of reducing the cost and risk of tests.In order to avoid the repeated work of developing models and improve the accuracy and credibility of the start-up model,it is necessary to carry out the study of establishing start-up general models and correction technology of the start-up model.The first part of the paper analyzes the structure of the common aero-engines and generalizes the models of the components of these aero-engines.Then a general component-level start-up model library for turbojet,turbofan and turboshaft engines is established.The general component-level start-up model library is validated through simulation,which lays the foundation for the following work on studying the method to calculate initial guess values,the correction of start-up models and the optimization of control laws.The manual method of selecting initial guess values of the component-level start-up model is summarized.Through taking advantages of the monotonic feature of low-speed aero-engine component characteristics,a new method based on the principle of flow balance abided by components in starting up process to calculate initial guess values is studied.The simulation results of various types of aero-engine start-up models show that the method is effective.The influence of the internal correction factors of the start-up model existing in the starting up process is analyzed.The correction of total pressure recovery coefficients and combustion efficiency of the combustor in the starting up phase is mainly studied.Then,a general manual correction method for the start-up model is summarized.The validity of the correction method is verified by taking the correction of a turbojet engine as an example.Finally,the rotor resistance model is established in order to improve the simulation accuracy of the starting up process.Aiming at solving the problem existing in the start-up and transition-state control of a turboshaft engine at present,the optimization measures and schemes of the starting control law and the transition-state control law are studied.The validity and feasibility of the optimization method are verified on the modified high-precision model.