科氏效应对叶片-桨毂-轴耦合系统振动特性的影响规律研究

Coriolis effect on vibration characteristics of blade-hub-shaft coupling system

采用几何精确模型与阶次截断方法描述叶片的空间变形,建立了考虑科氏效应与离心刚化作用的叶片-桨毂-轴耦合系统动力学模型,推导了耦合系统振动微分方程。采用Rayleigh-Ritz法进行数值离散,计算了不同刚度比、半径比、转速和叶片数下,科氏效应对系统模态频率的影响。研究表明:叶片-桨毂-轴耦合系统模态中包含耦合和非耦合两类模态,耦合模态频率在考虑科氏效应后发生明显降低;随着半径比增加,科氏效应对第1阶耦合模态频率的影响逐渐减弱,对第2阶耦合模态频率的影响逐渐增强;转速的增加会提升耦合模态对科氏效应的敏感性;刚度比处于10;~10;范围内时发生叶片模态振型转换的现象,模态振型转换后科氏效应的影响更为显著;随着叶片数目的增加,科氏效应对模态频率的影响逐渐减弱。研究结果可为旋转叶片-桨毂-轴耦合系统的动力学设计提供理论参考。

Geometry exact model and order reservation approach were adopted to describe the spatial deformation of the blade, the dynamic model of the blade-hub-shaft coupling system considering the Coriolis effect and the centrifugal stiffening effect was established, and the vibration differential equation of the coupling system was derived.The Rayleigh-Ritz method was used for numerical dispersion, and the influence of the Coriolis effect on the system modal frequency was calculated under different stiffness ratios, radius ratios, rotation speeds and blade numbers.The research shows that the modes of blade-hub-shaft coupling system consist of two types of coupled and uncoupled modes.The frequency of the coupled mode is significantly reduced after considering the Coriolis effect.As the radius ratio increases, the influence of the Coriolis effect on the first order coupled modal frequency is gradually weakened, and the influence on the second-order coupled modal frequency is gradually strengthened;the raise of the rotational speed will improve the sensitivity of the coupled modal to the Coriolis effect;the blade modes shape conversion phenomenon occurs when the stiffness ratio is within the range of 10~3-10~5,the effect of the Coriolis effect becomes more significant after the mode shape conversion.As the number of blades increases, the influence of the Coriolis effect on the modal frequency gradually decreases.The research results provide theoretical reference for the dynamic design of the rotating blade-hub-shaft coupling system.