The Research On Vibration Localization In Grouped Bade-disk

In steam turbine’s last stage, the free standing blade disk has little used and the blades are usually assembled into groups of blades in order to increase their stiffness and fatigue strength. This kind of blade-disk is called grouped blade disk. Compared with free standing blade disk, the vibration characteristics of grouped blade disk are more complex because of the group characteristics. Although scholars at home and abroad have done much research on grouped blade disk, the research in grouped blade disk’s vibration localization is not enough. Therefore, the lumped parameter model and finite element model were established, and the vibration localization of grouped blade disk was systematically analyzed.Firstly, the lumped parameter model of grouped blade disk was established, and the natural frequencies and mode localization belong to tuned grouped blade disk were studied. In addition, a test bench was built to validate the inherent characteristics of grouped blade disk. The effect of group number on mode localization was discussed. On this basis, the researches on natural frequencies and mode in random mistuning have been done, and the principles of the effect of group number on natural frequencies and mode localization in random mistuning were revealed.Secondly, based on the lumped parameter model, the vibration response localization of grouped baled disk at harmonic excitation was analyzed. The effects of group number and group coupling stiffness on vibration response localization of tuned and random mistuned grouped blade disk were analyzed. What’s more, the effects of a single blade mistuning and mistuning distribution on vibration response localization were researched.Finally, in view of the shrouds’fatigue damage in grouped blade disk, the finite element of grouped blade disk was established. Based on the harmonic response, the influences of mistuning, mistuning strength and coupling strength to the shrouds’stress responses were preliminarily discussed, and the cause of shrouds’fatigue damage was revealed from the view of vibration localization.The conclusions in this paper could not only improve and complete the fundamental theories of the vibration localization of the grouped blade disk, but also provide a theoretical support for the optimized design of grouped blade disk.