Background

This paper presents the experimental and numerical studies of last-stage low-pressure (LP) mistuned steam turbine bladed discs during run-down.

Methods

The natural frequencies and mode shapes of the turbine bladed disc were calculated using an FE model. The influence of the shaft on the modal properties, such as natural frequencies and mode shapes, was considered. The tip-timing method was used to find the mistuned bladed disc modes and frequencies.

Conclusions

The experimental results from the tip-timing analysis show that the mistuning in combination with shaft coupling suppresses pure nodal diameter type blade vibrations associated with the fundamental mode shape of a cantilevered blade. Vibration modes emerge when even a single blade is vibrating due to the well-known mode localization caused by mistuning. The numerical results confirm this.

中文翻译：

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末期汽轮机失谐叶片盘的叶尖计时测量和数值分析

背景

本文介绍了失速期间末级低压（LP）雾化汽轮机叶片盘的实验和数值研究。

方法

涡轮叶片盘的固有频率和模式形状是使用有限元模型计算的。考虑了轴对模态特性的影响，例如固有频率和模态形状。尖端定时方法被用来发现被误解的叶片盘的模式和频率。

结论

尖端定时分析的实验结果表明，与轴联轴器组合使用的雾化抑制了与悬臂叶片基本模式形状相关的纯节点直径型叶片振动。由于众所周知的雾化引起的模式局部化，即使单个刀片振动时，也会出现振动模式。数值结果证实了这一点。