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Research Papers: Hydrodynamic Lubrication

Rotordynamic Morton Effect Simulation With Transient, Thermal Shaft Bow

[+] Author and Article Information
Xiaomeng Tong

Mem. ASME
Department of Mechanical Engineering,
Texas A&M University,
College Station, TX 77840
e-mail: tongxiaomeng1989@tamu.edu

Alan Palazzolo

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

Junho Suh

Mem. ASME
Department of Mechanical Engineering,
Texas A&M University,
College Station, TX 77840
e-mail: junhosuh77@gmail.com

Contributed by the Tribology Division of ASME for publication in the JOURNAL OF TRIBOLOGY. Manuscript received June 22, 2015; final manuscript received January 11, 2016; published online May 4, 2016. Assoc. Editor: Mihai Arghir.

J. Tribol 138(3), 031705 (May 04, 2016) (11 pages) Paper No: TRIB-15-1222; doi: 10.1115/1.4032961 History: Received June 22, 2015; Revised January 11, 2016

The Morton effect (ME) is characterized by an asymmetric journal temperature distribution, slowly varying thermal bow and intolerable synchronous vibration levels. The conventional mass imbalance model is replaced by a more accurate thermal shaft bow model. Rotor permanent bow and disk skew are synchronous excitation sources and are incorporated in the dynamic model to investigate their influence on the ME. A hybrid beam/solid element finite element shaft model is utilized to provide improved accuracy for predicting the rotor thermal bow and expansion, with practical computation time. ME is shown to be induced by initial shaft bow and disk skew. The conventional mass imbalance approach is shown to have some limitations.

Copyright © 2016 by ASME
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References

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Figures

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Fig. 1

Diagram illustrating the HFEM

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Fig. 2

Thermal load for solid elements

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Fig. 3

Static thermal deformation model

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Fig. 4

Force sources for the synchronous vibration

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Fig. 5

Staggered integration scheme

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Fig. 6

Flow diagram for ME transient simulation

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Fig. 7

Rotor–bearing configuration

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Fig. 8

Key response variables versus speed: (a) peak–peak vibration at the rotor NDE overhung disk and at the tilting pad bearing, (b) peak–peak temperature difference in the journal, (c) FFT of the tilting pad bearing vibration, and (d) minimum film thickness ratio

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Fig. 9

Thermal bow at various speeds: (a) thermal bow in the X–Z plane and (b) thermal bow in the Y–Z plane

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Fig. 10

Comparison of the thermal imbalance method and thermal bow method: (a) PK–PK vibration at rotor overhung end, (b) 1× polar plot of the NDE bearing, (c) PK–PK temperature difference in the shaft, and (d) minimum film thickness ratio

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Fig. 11

Configuration of the permanent bow and disk skew

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Fig. 12

Nonlinear transient analysis at 6 krpm with permanent bow: (a) PK–PK vibration at rotor NDE, (b) PK–PK temperature difference in shaft, and (c) 1× filtered polar plot at NDE bearing

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Fig. 13

Nonlinear transient analysis at 6 krpm with disk skew: (a) PK–PK vibration at rotor NDE, (b) PK–PK temperature difference in shaft, and (c) 1× filtered polar plot at NDE bearing

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Fig. 14

Photo and transverse stiffness of a coupling

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Fig. 15

Temperature distribution in the shaft

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Fig. 16

Thermal bow with various coupling stiffness values (N/m)

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Fig. 17

Transient analysis at 7500 rpm with various coupling stiffness (a) journal temperature difference and (b) 1× polar plot at the NDE bearing

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