0
Research Papers: Gas Turbines: Structures and Dynamics

Experimental Identification of Force Coefficients of Large Hybrid Air Foil Bearings

[+] Author and Article Information
Yu Ping Wang

Jacobs Technology Inc.,
600 William Northern Boulevard,
Tullahoma, TN 37388
e-mail: ypcwang@gmail.com

Daejong Kim

The University of Texas at Arlington,
Arlington, TX 76019
e-mail: daejongkim@uta.edu

1Corresponding author.

Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received August 26, 2013; final manuscript received August 29, 2013; published online November 27, 2013. Editor: David Wisler.

J. Eng. Gas Turbines Power 136(3), 032503 (Nov 27, 2013) (8 pages) Paper No: GTP-13-1324; doi: 10.1115/1.4025891 History: Received August 26, 2013; Revised August 29, 2013

Foil bearing technology using air or gas as a lubricant has been around since the mid-1960s, and it made significant progress in its reliability, performance, and applications. Even if significant progress has been made to the technology, the commercial applications to relatively large machines with journal shaft diameter bigger than 100 mm was not reported. This paper presents dynamic characteristics of a hybrid (hydrodynamic + hydrostatic) air foil bearing (HAFB) with a diameter of 101.6 mm and a length of 82.6 mm. The test rig configuration in this work is a floating HAFB on a rotating shaft driven by electric motor, and the HAFB is under external load. HAFB stiffness coefficients were measured using both (1) time-domain quasi-static load-deflection curves and (2) frequency-domain impulse responses, and HAFB damping coefficients were measured using only impulse responses. The HAFB direct stiffness coefficients measured from both methods are close to each other in the range of 4∼7 MN/m depending on speed, load, and supply pressure, but frequency domain method shows larger scatter in the identified coefficients. HAFB coefficients simulated with the linear perturbation method using a bump stiffness matched to the load-deflection characteristics at 18,000 rpm show reasonably good agreements with experimentally measured values.

Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.

References

Agrawal, G. L., 1997, “Foil Air/Gas Bearing Technology—An Overview,” Proceedings of the International Gas Turbine & Aeroengine Congress & Exhibition, Orlando, FL, June 2–5, ASME Paper No. 97-GT-347.
Radil, K., and Zeszotek, M., 2004, “An Experimental Investigation Into the Temperature Profile of a Compliant Foil Air Bearing,” STLE Tribol. Trans., 47(4), pp. 470–479. [CrossRef]
Radil, K., DellaCorte, C., and Zeszotek, M., 2007, “Thermal Management Techniques for Oil-Free Turbomachinery Systems,” STLE Tribol. Trans., 63(10), pp. 319–327. [CrossRef]
Swanson, E. E., Heshmat, H., and Walton, J., 2002, “Performance of a Foil-Magnetic Hybrid Bearing,” ASME J. Eng. Gas Turbines Power, 124(2), pp. 375–381. [CrossRef]
Swanson, E. E., and Heshmat, H., 2002, “Oil-Free Foil Bearings as a Reliable, High Performance Backup Bearing for Active Magnetic Bearings,” ASME Turbo Expo 2002: Power for Land, Sea, and Air, Amsterdam, The Netherlands, June 3–6, ASME Paper No. GT2002-30291. [CrossRef]
Kim, D., and Park, S., 2009, “Hydrostatic Air Foil Bearings: Analytical and Experimental Investigations,” Tribol. Int., 42(3), pp. 413–425. [CrossRef]
Kumar, M., and Kim, D., 2010, “Static Performance of Hydrostatic Air Bump Foil Bearing,” Tribol. Int., 43(4), pp. 752–758. [CrossRef]
Kim, D., and Lee, D., 2010, “Design of Three-Pad Hybrid Air Foil Bearing and Experimental Investigation on Static Performance at Zero Running Speed,” ASME J. Eng. Gas Turbines Power, 132(12), p. 122504. [CrossRef]
Kim, D., and Zimbru, G., 2012, “Start-Stop Characteristics and Thermal Behavior of A Large Hybrid Airfoil Bearing for Aero-Propulsion Applications,” ASME J. Eng. Gas Turbines Power, 134(3), p. 032502. [CrossRef]
Kumar, M., and Kim, D., 2008, “Parametric Studies on Dynamic Performance of Hybrid Air Foil Bearings,” ASME J. Eng. Gas Turbines Power, 130(6), p. 062501. [CrossRef]
Kim, D., and Varrey, M., 2012, “Imbalance Response and Stability Characteristics of a Rotor Supported by Hybrid Air Foil Bearings,” STLE Tribol. Trans., 55(4), pp. 529–538. [CrossRef]
Tiwari, R., Lees, A. W., and Friswell, M. I., 2004, “Identification of Dynamic Bearing Parameters: A Review,” Shock Vib. Dig., 36(2), pp. 99–124. [CrossRef]
Ertas, B. H., and Luo, H., 2008, “Nonlinear Dynamic Characterization of Oil-Free Wire Mesh Dampers,” ASME J. Eng. Gas Turbines Power, 130(3), p. 032503. [CrossRef]
Rubio, D., and San Andrés, L., 2007, “Structural Stiffness, Dry Friction Coefficient, and Equivalent Viscous Damping in a Bump-Type Foil Gas Bearing,” ASME J. Eng. Gas Turbines Power, 129(2), pp. 494–502. [CrossRef]
Song, J., and Kim, D., 2007, “Foil Gas Bearing With Compression Springs: Analyses and Experiments,” ASME J. Tribol., 129(3), pp. 628–639. [CrossRef]
San Andrés, L., and Chirathadam, T. A., 2011, “Metal Mesh Foil Bearing: Effect of Motion Amplitude, Rotor Speed, Static Load, and Excitation Frequency on Force Coefficients,” ASME J. Eng. Gas Turbines Power, 133(12), p. 122503. [CrossRef]
San Andrés, L., and Chirathadam, T. A., 2012, “A Metal Mesh Foil Bearing and a Bump-Type Foil Bearing: Comparison of Performance for Two Similar Size Gas Bearings,” ASME J. Eng. Gas Turbines Power, 134(10), p. 102501. [CrossRef]
DellaCorte, C., 2010, “Stiffness and Damping Coefficient Estimation of Compliant Surface Gas Bearings for Oil-Free Turbomachinery,” STLE/ASME 2010 International Journal of Tribology Conference, San Francisco, CA, October 17–20, Paper No. IJTC2010-41232.
Fritzen, C., 1986, “Identification of Mass, Damping, and Stiffness Matrices of Mechanical Systems,” ASME J. Vib., Acoust., Stress, Reliab. Des., 108(1), pp. 9–16. [CrossRef]
Diaz, S. E., and San Andrés, L., 1999, “A Method for Identification of Bearing Force Coefficients and Its Application to a Squeeze Film Damper With a Bubbly Lubricant,” STLE Tribol. Trans., 42, pp. 739–746. [CrossRef]
Wang, Y., 2012, “Experimental Identification of Force Coefficients of Hybrid Air Foil Bearings,” M.S. thesis, The University of Texas at Arlington, Arlington, TX.

Figures

Grahic Jump Location
Fig. 1

Photo of the three-pad HAFB, from Ref. [8]

Grahic Jump Location
Fig. 2

Photo of test rig. 1: proximity probes, 2: HAFB, and 3: duplex ball bearing support

Grahic Jump Location
Fig. 3

Load-deflection curves of HAFB with stationary shaft

Grahic Jump Location
Fig. 4

HAFB static stiffness KXX with stationary shaft (from load-deflection curves in Fig. 3)

Grahic Jump Location
Fig. 5

Load deflection curves of HAFB at 12,000 rpm; experiments versus simulation

Grahic Jump Location
Fig. 6

Load deflection curves of HAFB at 15,000 rpm; experiments versus simulation

Grahic Jump Location
Fig. 7

Load deflection curves of HAFB at 18,000 rpm; experiments versus simulation

Grahic Jump Location
Fig. 8

HAFB stiffness KXX from load-deflection curves at different supply pressures; experiments versus simulations. (a) 3.45 bar, (b) 4.14 bar, and (c) 4.83 bar.

Grahic Jump Location
Fig. 9

HAFB stiffness KXX from load-deflection curves at different speeds; experiments versus simulations. (a) 12,000 rpm, (b) 15,000 rpm, and (c) 18,000 rpm.

Grahic Jump Location
Fig. 10

Sleeve temperatures during measurements for all pressures, speeds, and loads

Grahic Jump Location
Fig. 11

Typical impulse response shown at 18 krpm, 356 N, 4.83 bar supply pressure; (a) direct responses and (b) cross-coupled responses

Grahic Jump Location
Fig. 12

Flexibility spectrum at 18 krpm, 356 N, 4.83 bar supply pressure; (a) HXX and (b) HYY

Grahic Jump Location
Fig. 13

Identification results for HAFB direct stiffness coefficients from impulse excitation, external load 222 N; (a) KXX and (b) KYY

Grahic Jump Location
Fig. 14

Identification results for HAFB direct damping coefficients from impulse excitation, external load 222 N; (a) DXX and (b) DYY

Grahic Jump Location
Fig. 15

Identification results for HAFB direct stiffness coefficients from impulse excitation, external load 356 N; (a) KXX and (b) KYY

Grahic Jump Location
Fig. 16

Identification results for HAFB direct damping coefficients from impulse excitation, external load 356 N; (a) DXX and (b) DYY

Grahic Jump Location
Fig. 17

Simulated frequency-dependent HAFB coefficients; 4.83 bar, 356 N, 18,000 rpm. (a) Stiffness coefficients and (b) damping coefficients.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In