Research On Aeroengine Active Stability Control Method

Aero-engine performance is limited by the stability of the compressor.For the purpose of making full use of the compression system by keeping the compressor stable under smaller flow and higher pressure and thereby reducing the stability margin,researchers arouse general interest on compressor active control.Focused on the key technology about active stability control design,stall and surge dynamics was analysed and the working mechanism of constant injection was studied firstly.Then the modal controller based on unsteady air injection and stall controller based on Lyapunov stability theory were designed.Finally,the common mechanism of three conventional actuators were summarized.Details and the academic innovations about this paper follow:Compressor stall and surge was analysed using bifurcation theory and strongly nonlinear oscillation theory based on Moore-Gretizer model.Theoretical values of Frequency and amplitude of stall cell and surge wave was derived from the dynamic analysis,from which we could get some critical factors affect stall and surge.And the theoretical values may be used on signal detecting.The working mechanism of air injection from the perspective of control was discussed,and the point that air injection stabilized compressor through shifting compressor characteristic was proposed.The impact of jet parameters was under quantitative research,which indicates that steady air injection is sensitive to magnitude of distortion and insensitive to frequency,and injected air speed is the critical factor affects the stability of compressor.Besides,there is the minimum injection speed which could stabilize compressor,and we confirmed the theoretical value about the speed.In contrast with steady air injection,the unsteady injection can expand compressor stability margin effectively.Aimed at the lack of compression system model with unsteady and the insufficient on theoretical analysis and explanation about stability control,the multidimensional compressor model with unsteady air injection was built considering the mass and momentum and unsteady effect.The effect of modal control was simulated which could be reference for unsteady air injection control system design.The local and global controllers using Lyapunov stability theory,which is rare on reference papers,was designed because of the shortcoming of multiplex sensor and high frequency actuator requirement for modal control.And the effect of controller was simulated.It indicated that the controllers using air injection could control stall and lower the requirement on hardware,which benefit the engineering application most.