Large unbalance vibration analysis of steam turbine generators. Final report

Technical Report · Sat Sep 01 00:00:00 EDT 1984

OSTI ID:6506485

Adams, Jr, M L

The purpose of this project was to pursue in more depth than earlier work the analysis of large-unbalance vibration in large steam turbine units. The earlier work served to identify a previously unrecognized mode of potentially massive failure, namely, high amplitude subharmonic resonance of the rotor/bearing system. This phenomenon appears to have possibly played a major role in three massive failures that are briefly reviewed herein. The more extensive results of the analyses performed in this project provide a greatly enhanced definition of what typical level of unbalance is required to trigger large amplitude subharmonic resonance. It was found on turbines operating below the oil-whip threshold speed that a critical magnitude of unbalance exists above which relatively small additional amounts of unbalance cause a rapid increase in subharmonic and overall vibrations to potentially catastrophic levels. Simultaneous occurrence of oil-whip vibration and a large rotor unbalance is shown to produce even substantially higher vibration and dynamic force levels than with the large unbalance alone. It was also found that the previously shown superiority of pivoted-pad journal bearings in controlling subharmonic resonance exists with or without pad preloading and with either rigid or typically flexible pivots for the bearing pads.

• Research Organization: Case Western Reserve Univ., Cleveland, OH (USA)
• OSTI ID: 6506485
• Report Number(s): EPRI-CS-3716; ON: TI85920011
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
42 ENGINEERING
STEAM GENERATORS
TURBINES
STEAM TURBINES
MECHANICAL VIBRATIONS
BEARINGS
MATHEMATICAL MODELS
ROTORS
BOILERS
MACHINERY
TURBOMACHINERY
VAPOR GENERATORS
200104* - Fossil-Fueled Power Plants- Components
420200 - Engineering- Facilities
Equipment
& Techniques