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Research Papers: Gas Turbines: Structures and Dynamics

Characteristics of a Spherical-Seat TPJB With Four Methods of Directed Lubrication—Part I: Thermal and Static Performance

[+] Author and Article Information
David M. Coghlan

Flint Hills Resources,
Joliet, IL 60410
e-mail: coghlan3@gmail.com

Dara W. Childs

Department of Mechanical Engineering,
Texas A&M University,
College Station, TX 77843
e-mail: dchilds@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 April 27, 2017; final manuscript received May 11, 2017; published online August 23, 2017. Editor: David Wisler.

J. Eng. Gas Turbines Power 139(12), 122502 (Aug 23, 2017) (13 pages) Paper No: GTP-17-1152; doi: 10.1115/1.4036969 History: Received April 27, 2017; Revised May 11, 2017

Static and thermal characteristics (measured and predicted) are presented for a four-pad, spherical-seat, tilting-pad journal bearing (TPJB) with 0.5 pivot offset, 0.6 L/D, 101.6 mm nominal diameter, and 0.3 preload in the load-between-pivots orientation. One bearing is tested four separate times in the following four different lubrication configurations: (1) flooded single-orifice (SO) at the bearing shell, (2) evacuated leading edge groove (LEG), (3) evacuated spray-bar blocker (SBB), and (4) evacuated spray-bar (SB). The LEG, SBB, and SB are all considered methods of “directed lubrication.” These methods rely on lubrication injected directly to the pad/rotor interface. The same set of pads is used for every test to maintain clearance and preload; each method of lubrication is added as an assembly to the bearing. Test conditions include surface speeds and unit loads up to 85 m/s and 2.9 MPa, respectively. Static data include rotor–bearing eccentricities and attitude angles. Thermal data include measured temperatures from 16 bearing thermocouples. Twelve of the bearing thermocouples are embedded in the babbitt layer of the pads, while the remaining four are oriented at the leading and trailing edge of the loaded pads exposed to the lubricant. Bearing thermocouples provide a circumferential and axial temperature gradient. The pivot stiffness (pad and pivot in series) is measured and incorporated into predictions.

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Figures

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Fig. 1

Four-pad spherical-seat TPJB

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Fig. 2

Thermal mixing and hot oil carry-over

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Fig. 3

SO feed type (conventional)

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Fig. 7

Seal arrangement used by Nicholas and Harris—adapted from Ref. [2]

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Fig. 8

Side view of bearing test rig. (1) Air turbine, (2) coupling, (3) test rotor, (4) hydraulic hub, (5) bearing housing, (6) hydraulic shaker, (7) pitch stabilizer, (8) shaker mounting frame, (9) pedestal, (10) ball bearing, (11) test rig base, (12) pulley, and (13) test oil outlet.

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Fig. 9

Front view of test rig from the nondrive end

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Fig. 10

Hydraulic shaker setup for bearing excitation. (1) Hydraulic shaker, (2) force transducer, (3) stinger, (4) accelerometer, (5) eddy-current probe, and (6) location of stator thermocouple.

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Fig. 11

Flooded configuration with labyrinth end seals installed (nominal end seal bore 101.93 mm)

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Fig. 12

Evacuated configuration (with pad retainers)

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Fig. 13

Bearing thermocouple layout viewed from drive end (babbitt layer and exposed)

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Fig. 14

Measured bearing cold clearance

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Fig. 15

Recreation of crushed Harris [9] clearance

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Fig. 16

Measured cold clearance and circular clearance estimate for each bearing configuration

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Fig. 17

Journal loci at 38 m/s

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Fig. 18

Journal loci at 53 m/s

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Fig. 19

Journal loci at 69 m/s

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Fig. 20

Journal loci at 85 m/s

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Fig. 21

X-eccentricity as a function of load at 38 m/s

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Fig. 22

X-eccentricity as a function of load at 53 m/s

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Fig. 23

X-eccentricity as a function of load at 69 m/s

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Fig. 24

X-eccentricity as a function of load at 85 m/s

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Fig. 25

Attitude angle as a function of load at 38 m/s

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Fig. 26

Attitude angle as a function of load at 53 m/s

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Fig. 27

Attitude angle as a function of load at 69 m/s

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Fig. 28

Attitude angle as a function of load at 85 m/s

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Fig. 29

Temperature profiles for the loaded pads with a unit load of 2.1 MPa

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Fig. 30

Pad C (second loaded pad) at 0.7 MPa—measured temperature rise at the babbitt leading edge

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Fig. 31

Pad C (second loaded pad) at 0.7 MPa—measured temperature rise at the 75% babbitt location

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Fig. 32

Pad C (second loaded pad) at 0.7 MPa—measured temperature rise at the babbitt trailing edge

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Fig. 33

Maximum temperature rise at 0.7 MPa

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Fig. 34

Maximum temperature rise at 2.1 MPa

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Fig. 35

Maximum temperature rise at 2.9 MPa

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