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Research Papers: Gas Turbines: Structures and Dynamics

Characteristics of a Spherical Seat TPJB With Four Methods of Directed Lubrication—Part II: Rotordynamic Performance

[+] Author and Article Information
David M. Coghlan

Flint Hills Resources,
Joliet, IL 60115
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), 122503 (Aug 23, 2017) (13 pages) Paper No: GTP-17-1153; doi: 10.1115/1.4036970 History: Received April 27, 2017; Revised May 11, 2017

Measured and predicted rotordynamic characteristics 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 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. Dynamic data includes four sets (one set for each bearing configuration) of direct and cross-coupled rotordynamic coefficients derived from measurements and fit to a frequency-independent stiffness-damping-mass (KCM) matrix model. The pivot stiffness (pad and pivot in series) is measured and incorporated into predictions.

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References

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Figures

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Fig. 1

Four-pad spherical seat TPJB

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Fig. 2

Spring, mass, damper model for fluid film

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Fig. 3

Generic key-seat pivot

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Fig. 4

Single orifice (SO) feed type (conventional)

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Fig. 5

Spray-bar blocker (SBB) feed type

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Fig. 6

Leading edge groove (LEG) feed type

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Fig. 7

Spray-bar (SB) feed type

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Fig. 8

Side view of bearing test rig adapted from Ref. [7]

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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

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Fig. 11

Real part of measured impedance values for the SBB at 53 m/s and 0.7 MPa

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Fig. 12

Imaginary part of measured impedance values for the SBB at 53 m/s and 0.7 MPa

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Fig. 13

Measured and predicted direct stiffness in the loaded direction as a function of speed at 0.7 MPa

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Fig. 14

Measured and predicted direct stiffness in the loaded direction as a function of speed at 2.1 MPa

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Fig. 15

Measured and predicted direct stiffness in the loaded direction as a function of speed at 2.9 MPa

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Fig. 16

Measured and predicted direct stiffness in the loaded direction as a function of load at 38 m/s

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Fig. 17

Measured and predicted direct stiffness in the loaded direction as a function of load at 53 m/s

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Fig. 18

Measured and predicted direct stiffness in the loaded direction as a function of load at 69 m/s

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Fig. 19

Measured and predicted direct stiffness in the loaded direction as a function of load at 85 m/s

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Fig. 20

Measured and predicted direct stiffness perpendicular to load as a function of speed at 0.7 MPa

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Fig. 21

Measured and predicted direct stiffness perpendicular to load as a function of speed at 2.1 MPa

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Fig. 22

Measured and predicted direct stiffness perpendicular to load as a function of speed at 2.9 MPa

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Fig. 23

Measured cross-coupled stiffness as a function of speed at 0.7 MPa

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Fig. 24

Measured cross-coupled stiffness as a function of speed at 2.1 MPa

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Fig. 25

Measured cross-coupled stiffness as a function of speed at 2.9 MPa

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Fig. 26

Measured cross-coupled stiffness as a function of load at 38 m/s

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Fig. 27

Measured cross-coupled stiffness as a function of load at 53 m/s

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Fig. 28

Measured cross-coupled stiffness as a function of load at 69 m/s

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Fig. 29

Measured cross-coupled stiffness as a function of load at 85 m/s

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Fig. 30

Measured and predicted direct damping in the loaded direction as a function of speed at 0.7 MPa

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Fig. 31

Measured and predicted direct damping in the loaded direction as a function of speed at 2.1 MPa

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Fig. 32

Measured and predicted direct damping in the loaded direction as a function of speed at 2.9 MPa

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Fig. 33

Measured and predicted direct damping in the loaded direction as a function of load at 38 m/s

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Fig. 34

Measured and predicted direct damping in the loaded direction as a function of load at 53 m/s

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Fig. 35

Measured and predicted direct damping in the loaded direction as a function of load at 69 m/s

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Fig. 36

Measured and predicted direct damping in the loaded direction as a function of load at 85 m/s

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Fig. 37

Measured and predicted direct damping perpendicular to load as a function of speed at 0.7 MPa

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Fig. 38

Measured and predicted direct damping perpendicular to load as a function of speed at 2.1 MPa

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Fig. 39

Measured and predicted direct damping perpendicular to load as a function of speed at 2.9 MPa

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Fig. 40

Measured and predicted direct damping perpendicular to load as a function of load at 38 m/s

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Fig. 41

Measured and predicted direct damping perpendicular to load as a function of load at 53 m/s

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Fig. 42

Measured and predicted direct damping perpendicular to load as a function of load at 69 m/s

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Fig. 43

Measured and predicted direct damping perpendicular to load as a function of load at 85 m/s

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Fig. 44

Measured and predicted direct virtual mass in the loaded direction as a function of speed at 0.7 MPa

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Fig. 45

Measured and predicted direct virtual mass in the loaded direction as a function of speed at 2.1 MPa

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Fig. 46

Measured and predicted direct virtual mass in the loaded direction as a function of speed at 2.9 MPa

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