Hydrodynamic Lubrication

Morton Effect Cyclic Vibration Amplitude Determination for Tilt Pad Bearing Supported Machinery

[+] Author and Article Information
Alan Palazzolo

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

1Corresponding author.

Contributed by the Tribology Division of ASME for publication in the Journal of Tribology. Manuscript received January 17, 2012; final manuscript received September 11, 2012; published online December 20, 2012. Assoc. Editor: J. Jeffrey Moore.

J. Tribol 135(1), 011701 (Dec 20, 2012) (12 pages) Paper No: TRIB-12-1011; doi: 10.1115/1.4007884 History: Received January 17, 2012; Revised September 11, 2012

This paper presents theoretical models and simulation results for the synchronous, thermal transient, instability phenomenon known as the Morton effect. A transient analysis of the rotor supported by tilting pad journal bearing is performed to obtain the transient asymmetric temperature distribution of the journal by solving the variable viscosity Reynolds equation, a 2D energy equation, the heat conduction equation, and the equations of motion for the rotor. The asymmetric temperature causes the rotor to bow at the journal, inducing a mass imbalance of overhung components such as impellers, which changes the synchronous vibrations and the journal's asymmetric temperature. Modeling and simulation of the cyclic amplitude, synchronous vibration due to the Morton effect for tilting pad bearing supported machinery is the subject of this paper. The tilting pad bearing model is general and nonlinear, and thermal modes and staggered integration approaches are utilized in order to reduce computation time. The simulation results indicate that the temperature of the journal varies sinusoidally along the circumferential direction and linearly across the diameter. The vibration amplitude is demonstrated to vary slowly with time due to the transient asymmetric heating of the shaft. The approach's novelty is the determination of the large motion, cyclic synchronous amplitude behavior shown by experimental results in the literature, unlike other approaches that treat the phenomenon as a linear instability. The approach is benchmarked against the experiment of de Jongh.

© 2013 by ASME
Your Session has timed out. Please sign back in to continue.



Grahic Jump Location
Fig. 1

Thermohydrodynamic model boundary conditions

Grahic Jump Location
Fig. 2

Thermally induced rotor bend and overhung mass

Grahic Jump Location
Fig. 3

First four thermal modes with normalized temperature fields: (a) mode I, (b) mode II, (c) mode III, and (d) mode IV

Grahic Jump Location
Fig. 4

Verification of thermal mode approach: (a) computation domain, (b) boundary condition, (c) transient results, and (d) steady state solution

Grahic Jump Location
Fig. 5

Computation time versus mode number

Grahic Jump Location
Fig. 6

Flow chart for calculating time averaged journal temperatures for a given elliptical, synchronous orbit

Grahic Jump Location
Fig. 7

Flow chart: (a) full time transient analysis and (b) staggered integration scheme

Grahic Jump Location
Fig. 16

Effect of reducing the (a) bearing clearance (o: original system, m: modified system) or (b) lubricant viscosity

Grahic Jump Location
Fig. 15

Limit cycle at (a) 8000 rpm and (b) 9000 rpm

Grahic Jump Location
Fig. 14

Temperature difference versus revolutions for: (a) 7200, (b) 8000 rpm, and (c) 8500 rpm

Grahic Jump Location
Fig. 13

Morton effect simulation results: (a) 7200, (b) 8000, and (c) 8500 rpm

Grahic Jump Location
Fig. 12

FEM rotor model and test results [12]

Grahic Jump Location
Fig. 11

Maximum temperature difference across a journal diameter versus forward whirl radius ratio; ( ) phase angle between high spot and hot spot

Grahic Jump Location
Fig. 10

Temperature distribution in the shaft; forward whirl radius ratio (a) 0.05 and (b) 0.15

Grahic Jump Location
Fig. 9

Temperature distribution versus θ versus revolutions with a forward whirl radius ratio of 0.05

Grahic Jump Location
Fig. 8

Journal surface temperature comparison: (a) ΔT (pk-pk) versus εf, (b) temperature distribution on the journal surface at z/L = 0, and the (c) reference results plotted versus z and α




Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In