Critical Speed Analysis of a Single Stage Impulse Type High-Speed Steam Turbine Rotor Disc

Resonance is a common thread that runs through almost every branch of engineering. Yet, this phenomenon often goes unnoticed, silently resulting in inconveniences, such as causing a bridge to collapse or a helicopter to fl y apart, to name a few. It is, therefore, of utmost importance to avert resonance, for which determining the frequency of the system becomes indispensible. In complex rotating structures, as one considered in this paper, theoretical determination of frequency is as diffi cult and laborious as a task can be. Finite element analysis has proven to be an effective tool to handle such a task. Resonant vibrations incited by the running speed harmonic excitations, steam impinging frequency, engine order excitations are fundamental causes for failure of turbine components. The mainstream discipline that is encompassed by this paper is the modal analysis. Modal analysis is performed to estimate the critical speeds and study the mode shapes of the bladed rotor disc under prestressed condition.