非线性油膜力作用下叶片-转子-轴承系统弯扭耦合振动特性研究

RESEARCH ON COUPLED BENDING AND TORSION VIBRATION OF BLADE-ROTOR-BEARING SYSTEM WITH NONLINEAR OIL-FILM FORCE

建立了叶片-转子-轴承系统模型,并分析了考虑非线性油膜力作用下系统的弯扭耦合运动。为了考虑叶片弯曲变形的影响,将叶片模化为悬臂梁结构,利用假设模态法进行离散求解,通过Lagrange方法建立系统的运动方程,运用Runge-Kutta法对所得动力学方程进行数值求解,最终通过对分岔图、三维谱图、相图和Poincaré映射的分析,得到了叶片-转子-轴承系统中蕴含的各种复杂非线性动力学行为。通过与不考虑叶片的转子-轴承系统进行比较,指出叶片的弯曲振动使系统的不稳定区域提前,并在某些转速下激起系统的混沌运动。

A coupled bending and torsion model of blade-rotor-bearing with nonlinear oil-film force was presented.To analyze the impact of blade-bending,the blade was assumed to be a cantilever beam and then discretized using the assumed modes method.The motion equation was established by the Lagrange approach and numerically calculated by Runge-Kutta method.The bifurcation diagrams,waterfall plot,phase spectrum map and poincaré section were obtained to analyze dynamic characteristics of the system.The results reveal multiform complex nonlinear dynamic behavior of the blade-rotor-bearing system.Thorough a comparison with the system whose blades were not considered,it is shown that the blade-bending vibration advances the unstable region of the system and arises the chaotic motion of the system in some rotational speeds.