Predictions are presented for hole-pattern-stator seals for which the hole depth is varied axially, showing that various depth patterns can significantly improve damping performance in terms of both increasing the seal’s effective damping and reducing its crossover frequency—the frequency at which effective damping changes from positive to negative. Test results are presented for the seal with the best variable hole depth (VHD) pattern showing an increase in peak damping by a factor of 1.6 over a constant hole depth (CHD) design versus predictions of 2.7. The crossover frequency is reduced by approximately 40%. The VHD seal has a significant negative static stiffness that probably arises from a friction-factor-jump phenomenon, not flow path divergence. The VHD seal leaks less than a comparable CHD design.
Issue Section:
Gas Turbines: Structures and Dynamics
1.
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, D.
, and Moyer
, D.
, 1985, “Vibration Characteristics of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine)
,” ASME J. Eng. Gas Turbines Power
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.2.
Yu
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, and Childs
, D.
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,” ASME J. Eng. Gas Turbines Power
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.3.
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,” Proceedings, 31st Texas A&M University Turbomachinery Symposium
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, and Childs
, D.
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,” ASME J. Eng. Gas Turbines Power
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.5.
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, D.
, and Wade
, J.
, 2004, “Rotordynamic-Coefficient and Leakage Characteristics for Hole-Pattern-Stator Annular Gas Seals—Measurements Versus Predictions
,” ASME J. Tribol.
0742-4787, 126
(2
), pp. 326
–333
.6.
Sprowl
, B.
, and Childs
, D.
, 2004, “A Study of the Effects of Inlet Preswirl on the Dynamic Coefficients of a Straight-Bore Honeycomb Gas Damper Seal
,” ASME Paper No. GT2004-53328.7.
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, 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
0742-4795, 124
, pp. 958
–963
.8.
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, 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.
0742-4787, 125
, pp. 422
–429
.9.
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, C.
, and Childs
, D.
, 1993, “A Parameter Identification Method for the Rotordynamic Coefficients of a High Reynolds Number Hydrostatic Bearing
,” ASME J. Vibr. Acoust.
0739-3717, 115
, pp. 264
–270
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, B.
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,” M.S. thesis, Mechanical Engineering Department, Texas A&M University.11.
Ha
, T.-W.
, and Childs
, D.
, 1992, “Friction-Factor Data for Flat-Plate Tests of Smooth and Honeycomb Surfaces
,” ASME J. Tribol.
0742-4787, 114
, pp. 722
–730
.12.
Ha
, T.-W.
, Morrison
, G.
, and Childs
, D.
, 1992, “Friction-Factor Characteristics for Narrow-Channels With Honeycomb Surfaces
,” ASME J. Tribol.
0742-4787, 114
, pp. 714
–721
.13.
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, A.
, 1958, “Calculation of Critical Numbers of Revolutions and the Conditions Necessary for Dynamic Stability of Rotors in High-Pressure Hydraulic Machines When Taking Into Account Forces Originating in Sealings
,” Power and Mechanical Engineering
, 4
, pp. 1
–5
.14.
Smalley
, A. J.
, Camatti
, M.
, Childs
, D.
, Hollingsworth
, J.
, Vannini
, G.
, and Carter
, J.
, 2004, “Dynamic Characteristics of the Diverging-Taper Honeycomb-Stator Seal
,” ASME Paper No. GT2004-53084.15.
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, M.
, Vanini
, G.
, Fulton
, J.
, and Hopenwasser
, F.
, 2003, “Instability of a High Pressure Compressor Equipped With Honeycomb Seals
,” Proceedings of the 32nd Texas A&M University Turbomachinery Symposium
, September, pp. 39
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, J.
, and Hayles
, G.
, 2004, “Low Frequency Instability in a Process Compressor
,” Proceedings of the 33rd Texas A&M University Turbomachinery Symposium
, September, pp. 25
–32
.Copyright © 2008
by American Society of Mechanical Engineers
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