Reduced oil supply flow rates in fluid film bearings can cause cavitation, or lack of a fully developed hydrodynamic film layer, at the leading edge of the bearing pads. Reduced oil flow has the well-documented effects of higher bearing operating temperatures and decreased power losses; however, little experimental data of its effects on system stability and performance can be found in the literature. This study looks at overall system performance through observed subsynchronous vibration (SSV) patterns of a test rig operating under reduced oil supply flow rates. The test rig was designed to be dynamically similar to a high-speed industrial compressor. It consists of a flexible rotor supported by two tilting pad bearings in vintage, flooded bearing housings. Tests were conducted over a number of supercritical operating speeds and bearing loads, while systematically reducing the oil supply flow rates provided to the bearings. A low amplitude, broadband SSV pattern was observed in the frequency domain. During supercritical operation, a distinctive subsynchronous peak emerged from the broadband pattern at approximately half of the running speed and at the first bending mode of the shaft. Under lightly loaded conditions, the amplitude of the subsynchronous peak increased dramatically with decreasing oil supply flow rate and increasing operating speed. Under an increased load condition, the subsynchronous peak was largely attenuated. A discussion on the possible sources of this SSV including self-excited instability and pad flutter forced vibration is provided with supporting evidence from thermoelastohydrodynamic (TEHD) bearing modeling results.
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October 2018
Research-Article
Subsynchronous Vibration Patterns Under Reduced Oil Supply Flow Rates
Bradley R. Nichols,
Bradley R. Nichols
Rotating Machinery and Controls Laboratory,
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mails: brn7 h@virginia.edu;
brad.nichols@rotorsolution.com
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mails: brn7 h@virginia.edu;
brad.nichols@rotorsolution.com
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Roger L. Fittro,
Roger L. Fittro
Rotating Machinery and Controls Laboratory,
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mail: fittro@virginia.edu
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mail: fittro@virginia.edu
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Christopher P. Goyne
Christopher P. Goyne
Rotating Machinery and Controls Laboratory,
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mail: goyne@virginia.edu
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mail: goyne@virginia.edu
Search for other works by this author on:
Bradley R. Nichols
Rotating Machinery and Controls Laboratory,
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mails: brn7 h@virginia.edu;
brad.nichols@rotorsolution.com
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mails: brn7 h@virginia.edu;
brad.nichols@rotorsolution.com
Roger L. Fittro
Rotating Machinery and Controls Laboratory,
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mail: fittro@virginia.edu
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mail: fittro@virginia.edu
Christopher P. Goyne
Rotating Machinery and Controls Laboratory,
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mail: goyne@virginia.edu
Department of Mechanical and
Aerospace Engineering,
University of Virginia,
Charlottesville, VA 22904
e-mail: goyne@virginia.edu
1Corresponding author.
2Present address: Rotor Bearing Solutions International, Charlottesville, VA 22911.
Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received July 11, 2017; final manuscript received August 31, 2017; published online July 9, 2018. Editor: David Wisler.
J. Eng. Gas Turbines Power. Oct 2018, 140(10): 102503 (8 pages)
Published Online: July 9, 2018
Article history
Received:
July 11, 2017
Revised:
August 31, 2017
Citation
Nichols, B. R., Fittro, R. L., and Goyne, C. P. (July 9, 2018). "Subsynchronous Vibration Patterns Under Reduced Oil Supply Flow Rates." ASME. J. Eng. Gas Turbines Power. October 2018; 140(10): 102503. https://doi.org/10.1115/1.4038363
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