NDLI: Free Vibration in a Mistuned Steam Turbine Last Stage Bladed Disk

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Drewczynski, Marcin Rzadkowski, Romuald Maurin, Artur Marszalek, Piotr
Copyright Year	2015
Abstract	The design of blades in the last stage of a steam turbine is one of the most demanding engineering tasks in the turbomachinery field. Increasing turbine efficiency has led to the designing of higher tip-to-hub ratios. Slender blading conforms to reliability requirements, such as high blade stiffness and a high first mode natural frequency. Several high vibration amplitude problems were reported regarding a slender last stage blading of a commercial low-pressure steam turbine. During maintenance it was decided that the blades would be geometrically mistuned to prevent self-excitation. This paper presents a numerical study of LP steam turbine last stage bladed disk mistuning. Two different approaches to mistuning were applied and numerically compared: geometrical and material. The mode shapes and natural frequencies of the steam turbine bladed disk were calculated on the basis of an FEM model. The smallest range of mistuning (0,5Hz) in a bladed disk contaminates nodal diameters up to the fourth series. This should be taken into account when tip-timing method is adapted for steam turbine operation monitoring.
Sponsorship	International Gas Turbine Institute
File Format	PDF
ISBN	9780791856772
DOI	10.1115/GT2015-42080
Volume Number	Volume 7B: Structures and Dynamics
Conference Proceedings	ASME Turbo Expo 2015: Turbine Technical Conference and Exposition
Language	English
Publisher Date	2015-06-15
Publisher Place	Montreal, Quebec, Canada
Access Restriction	Subscribed
Subject Keyword	Vibration Blades Turbomachinery Maintenance Steam turbines Finite element methods Pressure Design Mode shapes Finite element model Free vibrations Disks Stiffness Excitation Reliability Turbines
Content Type	Text
Resource Type	Article

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