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Research Papers: Gas Turbines: Structures and Dynamics

Hole-Pattern and Honeycomb Seal Rotordynamic Forces: Validation of CFD-Based Prediction Techniques

[+] Author and Article Information
Kenny Krogh Nielsen

e-mail: kenny.krogh-nielsen@lr-ods.com

Kasper Jønck

Lloyd's Register ODS,
2900 Hellerup, Denmark

Harald Underbakke

Statoil,
NO-4035 Stavanger, Norway
e-mail: hun@statoil.com

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received June 27, 2012; final manuscript received July 6, 2012; published online October 11, 2012. Editor: Dilip R. Ballal.

J. Eng. Gas Turbines Power 134(12), 122505 (Oct 11, 2012) (10 pages) doi:10.1115/1.4007344 History: Received June 27, 2012; Revised July 06, 2012

This paper deals with modeling of hole-pattern and honeycomb seals. These are frequently used as balance piston seals in high pressure centrifugal compressor applications as they have the potential to facilitate superior rotordynamic damping characteristics while providing good leakage control. On the other hand it is also well-established that the rotordynamic performance of hole-pattern and honeycomb seals is very sensitive to convergence and divergence in the streamwise direction. The Isotseal bulk-flow code has shown difficulties in predicting the rotordynamic coefficients for convergent seal geometries or in cases with negative preswirl. This has led to increased interest in CFD-based analysis of seal dynamics. CFD-based models generally have less assumptions and are applicable for complex geometries or operating ranges not covered by bulk-flow codes. The CFD-based Instationary Perturbation Model (IPM) is utilized for the analysis of the hole-pattern and honeycomb seals. The rotordynamic forces are obtained by means of a time-dependent perturbation of the rotor position with respect to the stator. A sequence of perturbation frequencies is utilized to obtain the frequency dependence of the rotordynamic seal force coefficients. A strong effort has been put into validating the CFD-based perturbation modeling techniques against published experimental seal test data and the paper describes selected validation cases. A constant-clearance hole-pattern seal and a convergent honeycomb seal are analyzed and the results are compared to experimental results. The frequency dependence of the rotordynamic stiffness and damping characteristics of the seals is very well-captured for both types of seals.Finally, the IPM method was applied to a convergent hole-pattern seal to investigate the effects of eccentricity on the rotordynamic coefficients. The results are consistent with available experimental data.

Copyright © 2012 by ASME
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References

van der Velde, D. E., and Childs, D. W., 2008, “Measurements Versus Predictions for Rotordynamic and Leakage Characteristics of a Convergent-Tapered, Honeycomb-Stator/Smooth-Rotor Annular Gas Seal,” Proceedings of the ASME Turbo Expo 2008: Power for Land, Sea and Air, Paper No. GT2008-50068, pp. 883–889. [CrossRef]
Dietzen, F. J., and Nordmann, R., 1987, “Calculating Rotordynamic Coefficients of Seals by Finite-Difference Techniques,” ASME J. Tribol., 109, pp. 388–394. [CrossRef]
Arghir, M., and Frene, J., 1995, “Determination des Caracteristiques Statiques et Dynamiques des Joints Rainures Fonctionnant en Position Centree. Rapport Final,” Contrat de Collaboration No. 2L3994/EP639, EDF/LMS, Universite de Poitiers.
Arghir, M., and Frene, J., 1997, “Forces and Moments Due to Misalignment Vibrations in Annular Liquid Seals Using the Averaged Navier-Stokes Equations,” ASME J. Tribol., 119, pp. 279–287. [CrossRef]
Arghir, M., and Frene, J., 1997, “Analysis of a Test Case for Annular Seal Flows,” ASME J. Tribol., 119, pp. 408–414. [CrossRef]
Baskharone, E. A., and Hensel, S. J., 1991, “A Finite-Element Perturbation Approach to Fluid/Rotor Interaction in Turbomachinery Elements. Part 1: Theory,” ASME J. Fluids Eng., 113, pp. 353–361. [CrossRef]
Baskharone, E. A., and Hensel, S. J., 1991, “A Finite-Element Perturbation Approach to Fluid/Rotor Interaction in Turbomachinery Elements. Part 2: Application,” ASME J. Fluids Eng., 113, pp. 362–367. [CrossRef]
Przekwas, A. J., and Athavale, M. M., 1992, “Development of a CFD Code for Fluid Dynamic Forces in Seals,” Proceedings of the 1992 Seals Flow Code Development Workshop (CP-10124), NASA Lewis Research Center, Cleveland, OH, Aug. 5-6, pp. 68–84, available at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940017317_1994017317.pdf
Nielsen, K. K., 2001, “Application of CFD for Calculating Rotordynamic Forces from Leakage Flows in Turbomachinery,” Ph.D. thesis, Aalborg University, Aalborg, Denmark.
Tam, L. T., Przekwas, A. J., Musznska, A., Hendricks, R. C., Braun, M. J., and Mullen, R., 1988, “Numerical and Analytical Study of Fluid Dynamic Forces in Seals and Bearings,” ASME J. Vib., Acoust., Stress, Reliab. Des., 110, pp. 315–325. [CrossRef]
Athavale, M. M., Przekwas, A. J., and Hendricks, R. C., 1992, “A Finite-Volume Numerical Method to Calculate Fluid Forces and Rotordynamic Coefficients in Seals,” Proceedings of the AIAA 29th Joint Propulsion Conference, Nashville, TN, July 6–8, Paper No. AIAA-1992-3712.
Bhattacharya, A., 1997, “CFD Based Rotordynamics Coefficients for Labyrinth Seals and Impeller Shroud Leakage Paths,” M.S. thesis, Texas A&M University, College Station, TX.
Moore, J. J., 1999, “Rotordynamic Prediction of Centrifugal Impeller Shroud Passages Using Computational Fluid Dynamic Techniques With a Combined Primary/Secondary Flow Model,” Ph.D. thesis, Texas A&M University, College Station, TX.
Chochua, G., and Soulas, T., 2007, “Numerical Modeling of Rotordynamic Coefficients for Deliberately Roughened Stator Gas Annular Seals,” ASME J. Tribol., 129, pp. 424–428. [CrossRef]
Yan, X., Li, J., and Feng, Z., 2011, “Investigations on the Rotordynamic Characteristics of a Hole-Pattern Seal Using Transient CFD and Periodic Circular Orbit Model,” ASME J. Vib. Acoust., 133, 041007. [CrossRef]
Kleynhans, G., and Childs, D., 1997, “The Acoustic Influence of Cell Depth on the Rotordynamic Coefficients of Smooth Rotor/Honeycomb Stator Annular Gas Seals,” ASME J. Eng. Gas Turbines Power, 119, pp. 949–957. [CrossRef]
Hirs, G., 1973, “A Bulk-Flow Theory for Turbulence in Lubricant Films,” ASME J. Lubr. Technol., 94, pp. 137–146. [CrossRef]
Dawson, M., Childs, D., Holt, C., and Philips, S., 2002, “Theory Versus Experiments for the Dynamic Impedances of Annular Gas Seals: Part 1—Test Facility and Apparatus,” ASME J. Eng. Gas Turbines Power, 24, pp. 958–963. [CrossRef]
Childs, D., and Wade, J., 2004, “Rotordynamic-Coefficient and Leakage Characteristics for Hole-Pattern Stator Annular Gas Seals—Measurements Versus Predictions,” ASME J. Tribol., 126, pp. 326–333. [CrossRef]
Van Der Velde Alvarez, D. E., 2006, “Test Versus Predictions for Rotordynamic and Leakage Characteristics of a Convergent-Tapered, Honeycomb-Stator/Smooth-Rotor Annular Gas Sea,” M.S. thesis, Texas A&M University, College Station, TX.
Weatherwax, M., and Childs, D., 2003, “Theory Versus Experiment for the Rotordynamic Characteristics of a High Pressure Honeycomb Annular Gas Seal at Eccentric Positions,” ASME J. Tribol., 125, pp. 422–429. [CrossRef]

Figures

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Fig. 1

Shaking motion of rotor in IPM analysis

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Fig. 4

Hole-pattern: reaction forces at 200 Hz

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Fig. 5

Hole-pattern: forces versus number of nodes

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Fig. 6

Hole-pattern: direct stiffness

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Fig. 7

Hole-pattern: cross-coupled stiffness

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Fig. 8

Hole-pattern: direct damping

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Fig. 9

Hole-pattern: cross-coupled damping

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Fig. 10

Hole-pattern: effective stiffness

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Fig. 11

Hole-pattern: effective damping

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Fig. 12

Honeycomb: direct stiffness

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Fig. 13

Honeycomb: cross-coupled stiffness

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Fig. 14

Honeycomb: direct damping

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Fig. 15

Honeycomb: cross-coupled damping

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Fig. 16

Honeycomb: effective stiffness

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Fig. 17

Honeycomb: effective damping

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Fig. 18

ECC. Hole-pattern: direct stiffness.

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Fig. 19

ECC. Hole-pattern: cross-coupled stiffness.

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Fig. 20

ECC. Hole-pattern: direct damping.

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Fig. 21

ECC. Hole-pattern: cross-coupled damping.

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Fig. 22

ECC. Hole-pattern: effective stiffness.

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Fig. 23

ECC. Hole-pattern: effective damping.

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