Abstract
Recently, the blade with friction damper has been used in the steam turbine and gas turbine to improve the blade reliability. Especially, for the long steam turbine blade of the low pressure end, the shrouded blade has been widely used, where the shroud of the blade on a disk gets contact with each other due to untwist deformation of the blade in rotation. The shrouded blade is designed so that the shroud surface gets contact with the adjacent shroud surface uniformly. The contact condition of the shroud (in other words, the equivalent stiffness and the damping caused by the shroud), however, may change remarkably blade by blade, because of the manufacturing tolerance, the blade deformation in operation, the wear of the shroud, and so on. Therefore, it is indispensable to consider the mistuning effect caused by the variation of the contact condition of the shroud, in evaluating the resonant response of the bladed disk with the shrouded blade. In this study, first, the nonlinear frequency response of the shrouded bladed is carried out, and the linear equivalent spring-mass model is assembled based on the results of the nonlinear analysis. Second, the response analysis of the mistuned bladed disk is carried out by use of the equivalent spring-mass model. From these results, the effect of the variation of the contact condition of the shroud on the response is clarified.
Published Version
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