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Research Papers

Dynamic Response Analysis of Balance Drum Labyrinth Seal Groove Geometries Optimized for Minimum Leakage1

[+] Author and Article Information
Alexandrina Untaroiu

Laboratory for Turbomachinery
and Components,
Department of Biomedical Engineering
and Mechanics,
Virginia Tech,
495 Old Turner Street,
Blacksburg, VA 24061
e-mail: alexu@vt.edu

Neal Morgan

Rotating Machinery and Controls (ROMAC)
Laboratory,
Department of Mechanical and Aerospace
Engineering,
University of Virginia,
Charlottesville, VA 22903

Vahe Hayrapetian

Flowserve Corporation,
Vernon, CA 90058

Bruno Schiavello

Flowserve Corporation,
Bethlehem, PA 18017

2Corresponding author.

Contributed by the Technical Committee on Vibration and Sound of ASME for publication in the JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received April 28, 2016; final manuscript received November 27, 2016; published online February 22, 2017. Assoc. Editor: John Yu.

J. Vib. Acoust 139(2), 021014 (Feb 22, 2017) (9 pages) Paper No: VIB-16-1242; doi: 10.1115/1.4035380 History: Received April 28, 2016; Revised November 27, 2016

Annular labyrinth seals often have a destabilizing effect on pump rotordynamics due to the large cross-coupled forces generated when the fluid is squeezed by an oscillating rotor. In this study, several novel groove geometries are investigated for their effect on the rotordynamic coefficients of the labyrinth seal. The groove cavity geometry of a baseline 267 mm balance drum labyrinth seal with a clearance of 0.305 mm and 20 equally spaced groove cavities was optimized for minimum leakage. From the pool of possible groove designs analyzed, nine test cases were selected for maximum or minimum leakage and for a variety of groove cavity shapes. The rotordynamic coefficients were calculated for these cases using a hybrid computational fluid dynamics (CFD) bulk-flow method. The rotordynamic coefficients obtained by this method were then used with a rotordynamic model of the entire pump to determine the overall stability. Results show that labyrinth seal’s groove shape can be optimized to generate lower leakage rates, while the effects on dynamic properties are only minimally changed. If the seal dynamic response needs to be modified in addition to targeting a lower leakage rate, for instance, to exhibit increased damping values, then the leakage rate and the damping coefficient need to be set as objective functions in the optimization loop.

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References

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Untaroiu, A. , Untaroiu, C. D. , Wood, H. G. , and Allaire, P. E. , 2013, “ Numerical Modeling of Fluid-Induced Rotordynamic Forces in Seals With Large Aspect Ratios,” ASME J. Eng. Gas Turbines Power, 135(1), p. 012501. [CrossRef]
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Morgan, N. , Untaroiu, A. , Migliorini, P. J. , and Wood, H. G. , 2015, “ Design of Experiments to Investigate Geometric Effects on Fluid Leakage Rate in a Balance Drum Seal,” ASME J. Eng. Gas Turbines Power, 137(3), p. 032501. [CrossRef]
Untaroiu, A. , Hayrapetian, V. , Untaroiu, C. D. , Wood, H. G. , Schiavello, B. , and McGuire, J. , 2013, “ On the Dynamic Properties of Pump Liquid Seals,” ASME J. Fluids Eng., 135(5), p. 051104. [CrossRef]
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Figures

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Fig. 1

(a) Fluid flow path through seal geometry and (b) parameterization of the seal grooves

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Fig. 2

Seal model reduction

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Fig. 3

Direct stiffness coefficient response near the design point of minimum leakage, with respect to width and flat width

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Fig. 4

Direct stiffness coefficient response near the design point of minimum leakage, with respect to entrance angle and exit angle

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Fig. 5

Direct stiffness coefficient response near the design point of minimum leakage, with respect to width and depth

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Fig. 6

Groove geometry number 41, streamlines and pressure profile

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Fig. 7

Cross-coupled stiffness coefficient response near the design point of minimum leakage, with respect to width and flat width

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Fig. 8

Cross-coupled stiffness coefficient response near the design point of minimum leakage, with respect to entrance angle and exit angle

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Fig. 9

Cross-coupled stiffness coefficient response near the design point of minimum leakage, with respect to width and depth

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Fig. 10

Direct damping coefficient response near the design point of minimum leakage, with respect to width and flat width

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Fig. 11

Direct damping coefficient response near the design point of minimum leakage, with respect to entrance angle and exit angle

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Fig. 12

Direct damping coefficient response near the design point of minimum leakage, with respect to width and depth

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Fig. 13

Direct-mass coefficient response near the design point of minimum leakage, with respect to width and flat width

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Fig. 14

Direct-mass coefficient response near the design point of minimum leakage, with respect to entrance angle and exit angle

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Fig. 15

Direct-mass coefficient response near the design point of minimum leakage, with respect to width and depth

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Fig. 16

Selected test case groove geometry profiles

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Fig. 17

Natural frequency of full pump system with test case seal geometries

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Fig. 18

Log-decrement of full pump system with test case seal geometries

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