著者

金子 康智 岸本 星太 森 一石 大山 宏治

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.861, pp.17-00447-17-00447, 2018 (Released:2018-05-25)

参考文献数

13

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Although, in designing blades, it is assumed that all blades on a disk are identical (tuned system), the vibration characteristics of the blade is slightly different due to the manufacturing tolerance, the deviation of the material property, and so on (mistuned system). As a result, in the forced response of an actual bladed disk caused by the flow distortion, the responses of all the blades on a disk become different, and the response of a certain blade may become extremely large, due to the split of the duplicated natural frequencies, the distortion of the vibration modes, and so on. On the other hand, it is suggested by many researchers that the mistuning suppresses the blade flutter, because the complete travelling wave mode is not formed in a disk. In other words, the effect of the mistuning acts on the dangerous side for the forced vibration, while on the safety side for the blade flutter. In this study, the stability analysis and the frequency response analysis of mistuned bladed disks are carried out using the reduced model with high fidelity, in order to research the vibration characteristics of typical mistuned bladed disks. Based on the analysis results, an optimal design procedure of mistuned bladed disks considering both the forced response and the self-excited vibration is proposed.

著者

金子 康智 今井 貴彦 森 一石 大山 宏治

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.850, pp.16-00536-16-00536, 2017 (Released:2017-06-25)

参考文献数

9

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A vane used in a low pressure end of steam turbine is usually fixed to an inner shroud and an outer ring by welding both ends. In such a vane structure, the damping in loading operation is comprised of the material damping and the aerodynamic damping, because the structural damping is very small. In addition, steam turbine vanes are sometimes manufactured in a half-ring structure, where all vanes in a upper half and a lower half are connected by the shroud. In such a half-ring structure, the vane exhibits closely spaced natural frequencies of Toop (Tangential out-of-phase) modes, in which each vane in a half-ring vibrates like a fixed-fixed beam in a different phase. In such a steam turbine vane, the forced vibration and the self-excited vibration of Toop modes may become a serious issue. Therefore, in the design of the steam turbine vane, it becomes indispensable to evaluate the resonant response and the stability of Toop modes under the high loading condition. In this study, first, the vibration characteristics of steam turbine vane with a half-ring structure are studied by use of the results of FE analysis. Second, the reduced order model (the equivalent spring-mass model) of a half-ring structure is assembled, based on the results of FE analysis. Finally, the forced response analysis of the mistuned system of a half-ring structure is carried out, using the reduced order model and the Monte Carlo simulation. From these results, the vibration response characteristics of steam turbine vane with a half-ring structure are clarified.