抄録
Steam turbine vanes are usually manufactured in sectors (grouped vanes) consisting of several airfoils. As a consequence, the vane structure exhibits closely spaced natural frequencies of Toop (Tangential out-of-phase) modes, in which each vane in a sector 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 grouped vane structure are studied by use of the results of FE (Finite Element) analysis. Especially, the vibration characteristics of Toop modes are examined in detail. Second, the reduced order model (the equivalent spring-mass model) of the whole vane structure is assembled, based on the results of FE analysis. Finally, the forced response analysis of the mistuned whole vane structure is carried out, using the reduced order model and the Monte Carlo simulation. From these results, the vibration response characteristics of Toop modes of the whole vane structure are clarified.
