Design Of Control Schedule And Control Algorithm For Triple Bypass Variable Cycle Engine

Traditional aero engines are difficult to satisfy the long-range and multi-purpose military missions,so the variable cycle engine with the advantages of high unit thrust and low fuel consumption performance stands out.As a new conversion of variable cycle engine,the triple bypass variable cycle engine has a wider bypass adjustment range and lower fuel consumption,meanwhile the strong coupling,non-linearity,and strong interference brought by the increase of operating modes and adjustable mechanism has brought a great challenge to the related study of variable cycle engines.Designing and researching control schedules and control algorithms on key issues such as performance seeking control,multiple operating modes,and strong robustness are key part of the pre-development process for variable cycle engines.This article starts from the topic of the control schedule and control algorithm design of the triple bypass variable cycle engine,and carries out the following work:First,establish a component-level model of a triple bypass variable cycle engine.Corresponding mathematical models are established according to the working principles of key components such as FLADE fans,and triple bypass variable cycle engine component-level models are constructed.Statebalance equations for steady-state and dynamic models are constructed based on flow and static pressure balance.Simulation results show that the established model can perform steady state and transient state performance simulations of three typical operating modes.Secondly,study on the steady-state performance seeking control of the triple bypass variable cycle engine is carried out.Utilizing the NLPQL algorithm on the ISIGHT platform,for the three typical operating modes of single,double,and triple bypass,three optimization modes of maximum thrust,minimum fuel consumption,and minimum turbine front temperature are used to optimize the engine steady-state performance control plan.Simulation results show that the NLPQL algorithm can make variable cycle engines better perform their performance potential under three typical operating modes.Then,the optimal design of the transient state control plan of the triple bypass variable cycle engine is carried out.Using the ISIGHT platform,the maximum fuel flow that each discrete operating point can achieve under the current constraints is optimized in chronological order to obtain the shortest time acceleration plan.This paper proposes a performance coefficient matrix for the mode switching process,analyzes the effects of different adjustable mechanisms on engine performance,and optimizes the control plan for multiple mode switching processes based on different performance requirements and constraints.Finally,the study on the basic control algorithm of the triple bypass variable cycle engine is carried out.Using the augmented LQR algorithm,a steady-state mode controller is designed by adopting a method of controlling the high-pressure speed and the turbine drop pressure ratio in a closed loop of the fuel flow and the cross-sectional area of the throat of the tail nozzle.The fuel flow closed-loop control of high-pressure speed is adopted,and the remaining variables are open-loop adjusted.The design mode switch process controller is compared with the open-loop control plan designed in Chapter 4 to verify the effectiveness of the control plan.