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Research Papers: Gas Turbines: Structures and Dynamics

The Impact of Hole Depth on the Rotordynamic and Leakage Characteristics of Hole-Pattern-Stator Gas Annular Seals

[+] Author and Article Information
Dara W. Childs

The Leland T. Jordan Chair
of Mechanical Engineering
e-mail: dchilds@tamu.edu

Stephen Arthur

Graduate Research Assistant
e-mail: sarthur88@gmail.com
Turbomachinery Laboratory,
Texas A&M University,
College Station, TX 77843

Naitik J. Mehta

Mechanical Engineer-Rotating Equipment,
Bechtel OG&C,
Houston, TX 77056
e-mail: nmehta1@bechtel.com

Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received July 30, 2013; final manuscript received August 14, 2013; published online December 10, 2013. Editor: David Wisler.

J. Eng. Gas Turbines Power 136(4), 042501 (Dec 10, 2013) (6 pages) Paper No: GTP-13-1282; doi: 10.1115/1.4025888 History: Received July 30, 2013; Revised August 14, 2013

Test results are presented for rotordynamic characteristics of hole-pattern-stator annular gas seals at a 70 bar supply pressures with a running speed of 20,200 rpm. Leakage results are presented for these conditions and the additional speeds: 10,200 and 15,300 rpm. Hole-depth is the principal test variable of interest. Most published annular test data for these seals have a hole diameter of 3.175 mm and a hole depth of 3.302 mm. For this work, with the 3.175 mm hole diameter, additional results are presented for shallow (1.905 mm) and deep (6.604 mm) hole depths. Test results show a pronounced dependence of leakage and rotordynamic behavior on hole depth. Test results show much better leakage performance for the shallow-hole-depth seal in both leakage and rotordynamic performance. Compressor manufacturers and users will need to decide whether this observed performance improvement is worth trying in real machines.

FIGURES IN THIS ARTICLE
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Copyright © 2014 by ASME
Topics: Stators , Leakage , Damping
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References

Picardo, A., and Childs, D., 2005, “Rotordynamic Coefficients for a Teeth-on-Stator Labyrinth Seals at 70 Bar Supply Pressures—Measurements Versus Theory and Comparisons to a Honeycomb Seal,” ASME J. Eng. Gas Turbines Power, 127, pp. 843–855. [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]
Childs, D., Kheireddin, B., Phillips, S., and Asiravataham, T., 2011, “Friction Factor Behavior From Flat-Plate Tests of Smooth and Hole-Pattern Roughened Surfaces With Supply Pressures Up to 84 Bars,” ASME J. Eng. Gas Turbines Power, 133, p. 092504. [CrossRef]
Brown, P., and Childs, D., 2012, “Measurement Versus Predictions of Rotordynamic Coefficients of a Hole-Pattern Gas Seal With Negative Preswirl,” ASME Turbo Expo 2012, Copenhagen, Denmark, June 11–15, ASME Paper No. GT2012-68941. [CrossRef]
Mehta, N., and Childs, D., “Measured Comparison of Leakage and Rotordynamic Characteristics for a Slanted-Tooth and a Straight-Tooth Labyrinth Seal,” ASME-IGTI 2013 Turbo Expo, San Antonio, TX, June 3–7, ASME Paper No. GT2013-94035. [CrossRef]
Stanway, R., Burrows, C., and Holmes, R., 1978, “Pseudo-Random Binary Sequence Forcing in Journal and Squeeze Film Bearings,” ASLE Trans., 22(4), pp. 315–322. [CrossRef]
Prandtl, L., and Tietjens, O., 1934, Fundamentals of Hydro- and Aeromechanics, Dover Books on Aeronautical Engineering, New York.
Kleynhans, G., and Childs, D., 1997, “The Acoustic Influence of Cell Depth on the Rotordynamic Characteristics 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 Fluid Films,” ASME Trans. J. Lubr. Technol., 95(2), pp 137–146. [CrossRef]
Dawson, M., Childs, D., Holt, C., and Phillips, 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, 124, pp. 958–963. [CrossRef]
Weatherwax, M., and Childs, D., 2003, “The Influence of Eccentricity on the Leakage and Rotordynamic Coefficients of a High Pressure, Honeycomb, Annular Gas Seal. Measurements Versus Predictions,” ASME J. Tribol., 125, pp. 422–429. [CrossRef]

Figures

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Fig. 1

Test seal hole pattern [3]

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Fig. 2

Effect of varying hd on friction factor for smooth-on-hole configuration (Pin = 84 bar, Ø = 3.175 mm, and plate clearance = 0.635 mm) [3]

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Fig. 3

Cross section of the air seal test rig [1]

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Fig. 4

Test stator assembly [1]

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Fig. 5

Cross section view of the preswirl rings and pitot tube location [1]

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Fig. 6

Measured m· results for three hole depths

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Fig. 7

Measured Kxx*(Ω) results for three hole depths

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Fig. 8

Measured Kxy*(Ω) results for three hole depths

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Fig. 9

Measured Cxx*(Ω) results for three hole depths

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Fig. 10

Measured Ceff*(Ω) results for three hole depths

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