0
Research Papers: Gas Turbines: Structures and Dynamics

Improving Tilting Pad Journal Bearing Predictions—Part I: Model Development and Impact of Rotor Excited Versus Bearing Excited Impedance Coefficients

[+] Author and Article Information
Jason C. Wilkes

Research Engineer
Southwest Research Institute,
San Antonio, TX 78238
e-mail: jason.wilkes@swri.org

Dara W. Childs

Leland T. Jordan Prof. of
Mechanical Engineering,
Turbomachinery Laboratory,
Texas A&M University,
College Station, TX 77802
e-mail: dchilds@tamu.edu

Contributed by International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received July 2, 2012; final manuscript received July 5, 2012; published online December 4, 2012. Editor: Dilip R. Ballal.

J. Eng. Gas Turbines Power 135(1), 012502 (Dec 04, 2012) (14 pages) Paper No: GTP-12-1249; doi: 10.1115/1.4007367 History: Received July 02, 2012; Revised July 05, 2012

The floating-bearing-test-rig concept was initially developed by Glienicke in 1966 and has since been used to test many tilting-pad journal bearings (TPJBs). The impedances measured during these tests have been compared to rotor/journal-perturbed impedance predictions. Since the inertial acceleration of a pad is different for bearing-perturbed and rotor-perturbed motions, the bearing's reaction force components for bearing-perturbed and journal-perturbed motions will also differ. An understanding of how bearing-perturbed and rotor-perturbed impedances differ is needed to assess the validity of past, present, and future comparisons between TPJB test data and predictions. A new TPJB perturbation model is developed including the effects of angular, radial, and transverse pad motion and changes in pad clearance due to pad bending compliance. Though all of these pad variables have previously been included in different analyses, there are no publications containing perturbations of all four variables. In addition, previous researchers have only perturbed the rotor, while both the bearing and rotor motions are perturbed in the present analysis. The applicability of comparing rotor-perturbed bearing impedance predictions to impedances measured on a bearing-perturbed test rig is assessed by comparing rotor-perturbed and bearing-perturbed impedance predictions for an example bearing.

FIGURES IN THIS ARTICLE
<>
Copyright © 2013 by ASME
Your Session has timed out. Please sign back in to continue.

References

Lund, J. W., 1964, “Spring and Damping Coefficients for the Tilting-Pad Journal Bearing,” ASLE Trans., 7, pp. 342–352. [CrossRef]
Nilsson, L., 1978, “The Influence of Bearing Flexibility on the Dynamic Performance of Radial Oil Film Bearings,” Proceedings 5th Leeds-Lyon Symposium on Tribology, Lyon, France, September 19–22, Mechanical Engineering Publications, London, pp. 311–319.
Lund, J. W., and Pedersen, L.B., 1987, “The Influence of Pad Flexibility on the Dynamic Coefficients of a Tilting Pad Journal Bearing,” ASME J. Trib., 109(1), pp. 65–70. [CrossRef]
Glienicke, J., 1966, “Experimental Investigation of Stiffness and Damping Coefficients of Turbine Bearings and Their Application to Instability Predictions,” Proc. I.MechE., 181(3B), pp. 116–129.
Ha, H., and Yang, S., 1999, “Excitation Frequency Effects on the Stiffness and Damping Coefficients of a Five-Pad Tilting Pad Journal Bearing,” ASME J. Trib., 121, pp. 517–522. [CrossRef]
Rodriguez, L., and Childs, D., 2006, “Frequency Dependency of Measured and Predicted Rotordynamic Coefficients for Load-on-Pad Flexible-Pivot Tilting-Pad Bearing,” ASME J. Trib., 128(2), pp. 388–395. [CrossRef]
Carter, C., and Childs, D., 2008 “Measurements Versus Predictions for the Rotordynamic Characteristics of a 5-Pad, Rocker-Pivot, Tilting-Pad Bearing in Load Between Pad Configuration,” Proceedings of ASME Turbo Expo 2008, Berlin, Germany, June 9–13, ASME Paper No. GT2008-50069 [CrossRef].
Harris, J., and Childs, D., 2008, “Static Performance Characteristics and Rotordynamic Coefficients for a Four-Pad Ball-In-Socket Tilting Pad Journal Bearing,” Proceedings of ASME Turbo Expo 2008, Berlin, Germany, June 9–13, ASME Paper No. GT2008-50063. [CrossRef]
Delgado, A., Ertas, B., Drexel, M., Naldi, L., and Vannini, G., 2010, “Identification and Prediction of Force Coefficients in a Five-Pad and Four-Pad Tilting Pad Bearing for Load-on-Pad and Load-Between-Pad Configurations,” Proceedings of ASME Turbo Expo 2010, Glasgow, UK, June 14–18, ASME Paper No. GT2010-23802. [CrossRef]
Kulhanek, C., 2010, “Dynamic and Static Characteristics of a Rocker-Pivot, Tilting-Pad Bearing With 50% and 60% Offsets,” M.S. thesis, Mechanical Engineering, Texas A&M University, College Station, TX.
Kulhanek, C., and Childs, D., 2011, “Measured Static and Rotordynamic Coefficient Results for a Rocker-Pivot, Tilting-Pad Bearing With 50 and 60% Offsets,” Proceedings of ASME Turbo Expo 2011, Vancouver, Canada, June 6–10, ASME Paper No. GT2011-45209. [CrossRef]
Dmochowski, W., 2006, “Dynamic Properties of Tilting-Pad Journal Bearings: Experimental and Theoretical Investigation of Frequency Effects Due to Pivot Flexibility,” Proceedings of ASME Turbo Expo 2006, Barcelona, Spain, May 8–11, ASME Paper No. GT2006-90280 [CrossRef].
Pettinato, B., and De Choudhury, p., 1999, “Test Results of Key and Spherical Pivot Five-Shoe Tilt Pad Journal Bearings—Part I: Performance Measurements,” Trib. Trans., 42(3), pp. 541–547. [CrossRef]
Pettinato, B., and De Choudhury, p., 1999, “Test Results of Key and Spherical Pivot Five-Shoe Tilt Pad Journal Bearings—Part II: Dynamic Measurements,” Trib. Trans., 42(3), pp. 675–680. [CrossRef]
Al-Ghasem, A., and Childs, D., 2006, “Rotordynamic Coefficients Measurements Versus Predictions for a High-Speed Flexure-Pivot Tilting-Pad Bearing (Load-Between-Pad Configuration),” ASME J. Eng. Gas Turb. Power, 128(4), pp. 896–906. [CrossRef]
Rodriguez, L., 2006, “Frequency Dependency of Measured and Predicted Rotordynamic Coefficients for a Load-on-Pad Flexible-Pivot Tilting-Pad Bearing,” ASME J. Trib., 128(2), pp. 388–395. [CrossRef]
Hensley, J., 2006, “Rotordynamic Coefficients for a Load-Between-Pad Flexible-Pivot Tilting Pad Bearing at High Loads,” M.S. thesis, Mechanical Engineering, Texas A&M University, College Station, TX.
Kirk, R. G., and Reedy, S. W., 1988, “Evaluation of Pivot Stiffness for Typical Tilting-Pad Journal Bearing Designs,” J. Vib. Acoust. Stress Reliab. Des., 110(2), pp. 165–171. [CrossRef]
Earles, L., Palazzolo, A., and Armentrout, R., 1990, “A Finite Element Approach to Pad Flexibility Effects in Tilt Pad Journal Bearings—Part I: Single Pad Analysis,” ASME J. Trib., 112, pp. 169–177. [CrossRef]
Earles, L., Palazzolo, A., and Armentrout, R., 1990, “A Finite Element Approach to Pad Flexibility Effects in Tilt Pad Journal Bearings—Part II: Assembled Bearing and System Analysis,” ASME J. Trib., 112, pp. 178–182. [CrossRef]
Deeg, E., 1992, “New Algorithms for Calculating Hertzian Stresses, Deformations, and Contact Zone Parameters,” AMP J. Tech., 2, pp. 14–24, available at http://www.te.com/documentation/whitepapers/pdf/2jot_2.pdf
Wilkes, J., 2011, “Measured and Predicted Rotor-Pad Transfer Functions for a Rocker-Pivot Tilting-Pad Journal Bearing,” Ph.D. dissertation, Mechanical Engineering, Texas A&M University, College Station, TX.
Branagan, L., and Barrett, L., 1988, “Thermal Analysis of Fixed and Tilting Pad Journal Bearings Including Cross-Film Viscosity Variations and Deformations,” ROMAC Report No. 276, UVa Report No. UVA/643092/MAE88/376.
Deutschman, A., Michels, W., and Wilson, C., 1975, Machine Design, Macmillan Publishing Co., Inc., New York, pp. 862–863.
Lund, J. W., and Thomson, K. K., 1978, “A Calculation Method and Data for the Dynamic Coefficients of Oil-Lubricated Journal Bearings,” Topics in Fluid Journal Bearing and Rotor Bearing System, ASME, New York, pp. 1–28.
Nordmann, R., and Massmann, H., 1984, “Identification of Stiffness, Damping, and Mass Coefficients for Annular Seals,” Proceedings of the Institution of Mechanical Engineers (IMechE) Conference on Rotating Machinery, 3rd, Heslington, England, UK, September 11–13, pp. 167–181.
Knopf, E., and Nordmann, R., 1998, “Active Magnetic Bearings for the Identification of Dynamic Characteristics of Fluid Bearings,” Proceedings 6th International Symposium on Magnetic Bearings, Cambridge, MA, August 5–7.
Knopf, E., and Nordmann, R., 2000, “Identification of the Dynamic Characteristics of Turbulent Journal Bearings using Active Magnetic Bearings. Proceedings 7th International Conference on Vibrations in Rotating Machinery, Nottingham, England.
Szeri, A., 1980, Tribology: Friction, Lubrication, and Wear, McGraw-Hill Publishing, New York.
Jeng, W., 1995, “Bearing Dynamic Coefficients of Flexible-Pad Journal Bearings,” Trib. Trans., 38(2), pp. 253–260. [CrossRef]
Kim, J., Palazzolo, A., and Gadangi, R., 1995, “Dynamic Characteristics of TEHD Tilt Pad Journal Bearing Simulation Including Multiple Mode Pad Flexibility Model,” ASME J. Vib. Acoust., 117(1), pp. 123–135. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

Schematic of the journal, bearing, and kth pad in the reference state

Grahic Jump Location
Fig. 2

Rigid body degrees of freedom for a tilting pad

Grahic Jump Location
Fig. 3

Pivot reaction forces

Grahic Jump Location
Fig. 4

Pressure distribution on a tilting pad

Grahic Jump Location
Fig. 5

Change in pad curvature resulting from applied end moments

Grahic Jump Location
Fig. 6

Illustration of a pad with a pivot insert

Grahic Jump Location
Fig. 7

Schematic of the journal, bearing, and kth pad in a general position

Grahic Jump Location
Fig. 8

Schematic of the dynamic forces acting on the kth pad in a TPJB

Grahic Jump Location
Fig. 10

(a) Real and (b) imaginary impedances for bearing A with 10× heavier pads predicted relative to perturbations of the journal (jj) and bearing (bb) at 10,000 rpm and 1200 kPa unit load

Grahic Jump Location
Fig. 9

(a) Real and (b) imaginary impedances for bearing A predicted relative to perturbations of the journal (jj) and bearing (bb) at 10,000 rpm and 1200 kPa unit load

Grahic Jump Location
Fig. 11

(a) Real and (b) imaginary bearing impedances predicted relative to perturbations of the journal (jj) and journal-bearing (jb) at 4400 rpm and 1200 kPa (454 psi) unit load

Grahic Jump Location
Fig. 12

(a) Real and (b) imaginary impedances for bearing B predicted relative to perturbations of the journal (jj) and bearing (bb) at 3000 rpm and 1200 kPa unit load

Grahic Jump Location
Fig. 13

(a) Real and (b) imaginary impedances for bearing B predicted relative to perturbations of the journal (jj) and bearing (bb) at 3000 rpm and 300 kPa unit load

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