基于模态理论的叶片动频率计算方法

A Modal Method for the Calculation of Blade Dynamic Frequency

旋转状态下叶片动频率分布情况是叶片设计以及机组故障诊断必须考虑的重要因素。提出了一种基于模态分析理论 ,利用实测静态叶片模态参数重构旋转叶片动力方程 ,从而获得叶片在不同转速下的动频率。该方法可以考虑叶片径高比、叶片安装角、仰角的影响 ,可以考虑叶片切向和法向振动之间以及多模态之间的耦合 ,计算结果表明该方法具有很强的实用性。还提出了基于模态理论的叶片动频系数计算公式。最后结合实例进行了计算 。

The safe and reliable operation of a large turbo generator unit is directly influenced by the blade vibration characteristics of the turbo. The distribution of blade dynamic frequencies under rotation condition is an important factor that must be considered during the design stage and fault diagnosis. A new method for the calculation of blade dynamic frequencies is presented in this paper. The dynamic equation of the blade in operation state is reconstructed based on the static blade modal parameters. The dynamic frequencies are solved from the equation. The blade radius to length ratio, setting angle, altitude angle, coupling between two vibration directions and coupling between different modes can be considered in the new model. Another new method for the calculation of blade dynamic frequency coefficients is also presented. Example in the end of the paper shows that the accuracy is improved by the new method.