Static and dynamic load tests were performed on a three-pad, rocker-pivot, tilting-pad journal bearing (TPJB) with three interchangeable pad configurations, each with measurably different pad flexibilities. Measured dynamic-stiffness data for the bearing were readily fitted by a frequency-independent, constant-coefficient [K][C][M] model. The test-bearing had a 101.74 mm diameter with L/D = 0.6. Tests were conducted over the speed range of 6–12 krpm, with unit loads varying from 0.172 to 1.724 MPa. An ISO VG 46 lubricant was used as the test fluid. Pad flexibility was characterized as the change in the pad's bending stiffness or the change in pad thickness. A finite-element model (FEM) was created to predict the structural bending stiffness of each pad configuration, showing a significant pad flexibility increase as pad thickness decreased. To examine the effect of pad flexibility on the rotordynamic coefficients, the measured results were compared across pad configurations and showed that the pad flexibility increase reduced the direct damping coefficients by 12–20%. As pad flexibility increased, the direct-stiffness coefficients could increase or decrease, depending on the unit load. They varied from an increase of 12% at low unit loads to a decrease of 3% at high unit loads. Results show that the pad's structural bending stiffness or flexibility is important when predicting the bearing’s dynamic performance. Damping is consistently overpredicted when neglecting pad flexibility. A nondimensional pad flexibility parameter αflex was developed. It related the average deflection across the pad surface to the pad's arc length and was to relate the pad flexibility of multiple bearings of different sizes. A bearing code was used to predict the percent change in direct damping coefficients for rigid-pad/flexible-pivot and flexible-pad/flexible-pivot models for a surface speed of 54 m/s and a unit load of 783 kPa for the three-pad configuration tested here plus five additional tested bearings from the literature. For the minimum pad thickness configuration tested here, the code predicted a 20% drop in predicted Cxx (off-load axis direct damping) when comparing a model that included pad flexibility with a model that neglected pad flexibility. In terms of αflex, the two thinnest pad configurations tested here are quite flexible compared to both TPJB's pads used in industry and previously tested TPJB pads.
Skip Nav Destination
Article navigation
August 2016
Research-Article
The Impact of Pad Flexibility on the Rotordynamic Coefficients of Tilting-Pad Journal Bearings
Dara W. Childs
Dara W. Childs
Leland T. Jordan Professor of
Mechanical Engineering Department,
Texas A&M University,
College Station, TX 77840
e-mail: dchilds@turbo-lab.tamu.edu
Mechanical Engineering Department,
Texas A&M University,
College Station, TX 77840
e-mail: dchilds@turbo-lab.tamu.edu
Search for other works by this author on:
Jennifer E. Gaines
Dara W. Childs
Leland T. Jordan Professor of
Mechanical Engineering Department,
Texas A&M University,
College Station, TX 77840
e-mail: dchilds@turbo-lab.tamu.edu
Mechanical Engineering Department,
Texas A&M University,
College Station, TX 77840
e-mail: dchilds@turbo-lab.tamu.edu
Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received August 4, 2015; final manuscript received October 23, 2015; published online February 23, 2016. Editor: David Wisler.
J. Eng. Gas Turbines Power. Aug 2016, 138(8): 082501 (12 pages)
Published Online: February 23, 2016
Article history
Received:
August 4, 2015
Revised:
October 23, 2015
Citation
Gaines, J. E., and Childs, D. W. (February 23, 2016). "The Impact of Pad Flexibility on the Rotordynamic Coefficients of Tilting-Pad Journal Bearings." ASME. J. Eng. Gas Turbines Power. August 2016; 138(8): 082501. https://doi.org/10.1115/1.4032334
Download citation file:
Get Email Alerts
Cited By
Experimental Identification Of Blade Tip Rub Forces At Engine Relevant Temperatures And Speeds
J. Eng. Gas Turbines Power
Study Of Tandem Rotor Dual Wake Interaction With Downstream Stator Under Unsteady Numerical Approach
J. Eng. Gas Turbines Power
Experimental Design Validation of a Swirl-Stabilized Burner With Fluidically Variable Swirl Number
J. Eng. Gas Turbines Power (April 2025)
Experimental Characterization of a Bladeless Air Compressor
J. Eng. Gas Turbines Power (April 2025)
Related Articles
Rigid Mode Vibration Control and Dynamic Behavior of Hybrid Foil–Magnetic Bearing Turbo Blower
J. Eng. Gas Turbines Power (May,2017)
Transient Analysis of Gas-Expanded Lubrication and Rotordynamic Performance in a Centrifugal Compressor
J. Eng. Gas Turbines Power (April,2016)
Tilting Pad Journal Bearings: On Bridging the Hot Gap Between Experimental Results and Model Predictions
J. Eng. Gas Turbines Power (February,2015)
Experimental Identification of Dynamic Force Coefficients for a 110 MM Compliantly Damped Hybrid Gas Bearing
J. Eng. Gas Turbines Power (July,2015)
Related Chapters
Fundamentals of Structural Dynamics
Flow Induced Vibration of Power and Process Plant Components: A Practical Workbook
Summary and Conclusions
Bearing Dynamic Coefficients in Rotordynamics: Computation Methods and Practical Applications
Experimental and Statistical Study on the Noise Generated by Surface Defects of Bearing Rolling Bodies
Bearing and Transmission Steels Technology