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Research Papers: Hydrodynamic Lubrication

Numerical Modeling and Analysis of Flexure-Pivot Tilting-Pad Bearing

[+] Author and Article Information
Junho Suh

Mem. ASME
School of Mechanical Engineering,
Pusan National University,
Busan 46241, South Korea
e-mail: junhosuh@pusan.ac.kr

Alan Palazzolo

Fellow ASME
Department of Mechanical Engineering,
Texas A&M University,
College Station, TX 77840
e-mail: a-palazzolo@tamu.edu

Yeon-Sun Choi

Department of Mechanical Engineering,
Sungkyunkwan University,
Suwon 16419, South Korea
e-mail: yschoi@yurim.skku.ac.kr

Contributed by the Tribology Division of ASME for publication in the JOURNAL OF TRIBOLOGY. Manuscript received September 5, 2015; final manuscript received March 3, 2017; published online May 26, 2017. Assoc. Editor: Mihai Arghir.

J. Tribol 139(5), 051704 (May 26, 2017) (13 pages) Paper No: TRIB-15-1331; doi: 10.1115/1.4036275 History: Received September 05, 2015; Revised March 03, 2017

This paper presents a new approach for modeling flexure-pivot journal bearings (FPJB) employing a three-dimensional (3D) elasto-hydro-dynamic (EHD) lubrication model. The finite element (FE) method is adopted for an analysis of the (1) pad-pivot dynamic behavior and the (2) fluid force. The isoviscosity Reynolds equation is utilized to calculate the fluid force acting on a flexure-pivot pad bearing and spinning journal. Computational efficiency is achieved utilizing modal coordinate transformation for the flexible pad-pivot dynamic analysis. Fluid film thickness plays a critical role in the solution of Reynolds equation and is evaluated on a node-by-node basis accounting for the pad and web deflections. The increased fidelity of the novel modeling approach provides rotating machinery designers with a more effective tool to analyze and predict rotor–bearing dynamic behavior.

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References

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Figures

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Fig. 1

Tilting motion around pivot: (a) Tilting pad bearing and (b) flexure pivot bearing

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Fig. 2

Three-dimensional flexible pad-pivot dynamic FE model

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Fig. 3

Node-based film thickness evaluation

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Fig. 4

Algorithm for nonlinear rotor–bearing transient analysis

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Fig. 5

Pad-pivot FE model with different of web thicknesses: (a) 1 mm, (b) 8 mm, and (c) 15 mm

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Fig. 6

Journal eccentricity ratio with varying web thickness: (a) 5000 rpm, (b) 10,000 rpm, and (c) 15,000 rpm

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Fig. 7

Journal attitude angle with varying web thickness: (a) 5000 rpm, (b) 10,000 rpm, and (c) 15,000 rpm

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Fig. 8

Stiffness coefficients with varying web thickness: (a) kxx at 5000 rpm, (b) kxx at 10,000 rpm, (c) kxx at 15,000 rpm, (d) kyy at 5000 rpm, (e) kyy at 10,000 rpm, (f) kyy at 15,000 rpm, (g) kxy at 5000 rpm, (h) kxy at 10,000 rpm, (i) kxy at 15,000 rpm, (j) kyx at 5000 rpm, (k) kyx at 10,000 rpm, and (l) kyx at 15,000 rpm

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Fig. 9

Damping coefficients with increasing web thickness: (a) cxx at 5000 rpm, (b) cxx at 10,000 rpm, (c) cxx at 15,000 rpm, (d) cyy at 5000 rpm, (e) cyy at 10,000 rpm, (f) cyy at 15,000 rpm, (g) cxy at 5000 rpm, (h) cxy at 10,000 rpm, (i) cxy at 15,000 rpm, (j) cyx at 5000 rpm, (k) cyx at 10,000 rpm, and (l) cyx at 15,000 rpm

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Fig. 10

Tilting angle and pivot radial deformation (dotted line: original shape and bold line: deformed shape): (a) Pivot and web tilting angle and (b) pivot radial deformation

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Fig. 11

Tilting angle: (a) 5000 rpm (pivot #1), (b) 10,000 rpm (pivot #1), (c) 15,000 rpm (pivot #1), (d) 5000 rpm (pivot #2), (e) 10,000 rpm (pivot #2), (f) 15,000 rpm (pivot #2), (g) 5000 rpm (pivot #3), (h) 10,000 rpm (pivot #3), and (i) 15,000 rpm (pivot #3)

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Fig. 12

Pivot radial deformation ratio: (a) 5000 rpm, (b) 10,000 rpm, and (c) 15,000 rpm

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Fig. 13

Dynamic coefficients with varying number of modes: (a) kxx, (b) kyy, (c) kxy and kyx, (d) cxx, (e) cyy, and (f) cxy and cyx

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Fig. 14

Static characteristics with varying number of modes: (a) Eccentricity ratio and (b) attitude angle

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Fig. 15

Mode shapes: (a) first mode, (b) third translational mode, (c) fifth bending mode, (d) eighth bending mode, (e) second torsional mode, (f) seventh mode, and (g) ninth mode

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Fig. 16

Stiffness coefficients versus rotor speeds for different bearing unit load: (a) 348.4 kPa and (b) 1038.2 kPa

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Fig. 17

Damping coefficients versus rotor speeds for different bearing unit load: (a) 348.4 kPa and (b) 1038.2 kPa

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