0
Research Papers: Gas Turbines: Structures and Dynamics

Thermohydrodynamic Analysis of Compliant Flexure Pivot Tilting Pad Gas Bearings

[+] Author and Article Information
Kyuho Sim

Mechanical Engineering, Texas A&M University, College Station, TX 77843-3123

Daejong Kim

Mechanical Engineering, Texas A&M University, College Station, TX 77843-3123djkim@tamu.edu

J. Eng. Gas Turbines Power 130(3), 032502 (Apr 02, 2008) (12 pages) doi:10.1115/1.2836616 History: Received June 11, 2007; Revised October 29, 2007; Published April 02, 2008

A new thermohydrodynamic (THD) analysis for compliant flexure pivot tilting pad gas bearings is presented. Unlike many previous THD analyses on oil-lubricated bearings and gas bearings, the new THD analysis solves the rotor and bearing pad temperatures as well as the gas film temperature simultaneously upon adequate thermal boundary conditions on the bearing shell and rotor ends are given. All the previous studies assume that the rotor and bearing temperatures are given as thermal boundary conditions to solve 2D or 3D energy equation in the bearing film. The developed computational method is unique because these boundary conditions are found internally through global energy balance around the bearing. A numerical procedure involves solving the generalized Reynolds equation, 3D energy equation, and heat flux equations around the bearings simultaneously through iterative process. Furthermore, rotor thermal and centrifugal expansions are also considered during the iteration. Parametric studies were performed for the various temperature fields, i.e., rotor temperature, gas film temperature, and pad temperature as a function of nominal clearance, external load, and various thermal boundary conditions. Nominal clearance showed the most significant influence on overall THD behavior. The analyses also show that the rotor-bearing system can go to thermal runaway if adequate cooling mechanism does not exist. Linear perturbation analysis was also performed to investigate the thermal effects on the rotordynamic performance. Rotor thermal growth and increased viscosity increased direct stiffness and damping coefficients compared to the isothermal case.

Copyright © 2008 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 2

Schematics of thermal subsystem of typical rotor-bearing configuration

Grahic Jump Location
Figure 3

Reference coordinates and variables describing the rotor and pad motions

Grahic Jump Location
Figure 4

Coordinate systems for the energy equation and the generalized Reynolds equation in the air film

Grahic Jump Location
Figure 5

Mass flow around the mixing chamber between pads

Grahic Jump Location
Figure 6

Heat flux model for bearing pads

Grahic Jump Location
Figure 7

Temperature field at pad and bearing shell; the numbers in scale bar are in °C

Grahic Jump Location
Figure 8

Flowchart for the THD analysis

Grahic Jump Location
Figure 9

Rotor temperature along the rotor axis, 60krpm, C=35μm

Grahic Jump Location
Figure 10

Pad temperatures and inlet flow temperatures to pads, 60krpm, C=35μm

Grahic Jump Location
Figure 11

2D cross-film temperature field in the xy plane at the axial center of Pad 3, 60krpm, C=35μm

Grahic Jump Location
Figure 12

Bulk film temperatures, 60krpm, C=35μm

Grahic Jump Location
Figure 13

Nondimensional film pressures in the circumferential direction at the axial center of each pad, 60krpm, C=35μm

Grahic Jump Location
Figure 14

Averaged temperatures of rotor, pad, and bulk film versus rotor speed

Grahic Jump Location
Figure 15

Rotor temperatures along the rotor axis with different clearances, C=30–40μm, 60krpm

Grahic Jump Location
Figure 16

Pad temperatures with different clearances, C=30–40μm, 60krpm

Grahic Jump Location
Figure 17

Bulk film temperatures along the circumferential direction at the axial center of Pad 3, C=30–40μm, 60krpm

Grahic Jump Location
Figure 18

Inlet flow temperatures to pads with different clearances, C=30–40μm, 60krpm

Grahic Jump Location
Figure 19

Equilibrium positions of rotor for different external loads, 60krpm, C=35μm

Grahic Jump Location
Figure 20

Rotor temperatures along the rotor axis for different external loads, 60krpm, C=35μm

Grahic Jump Location
Figure 21

Pad temperatures for different external loads, 60krpm, C=35μm

Grahic Jump Location
Figure 22

Inlet flow temperatures to pads for different external loads, 60krpm, C=35μm

Grahic Jump Location
Figure 23

Bulk film temperatures along the circumferential direction at the axial center of each pad for external load of 28.40N, 60krpm, C=35μm

Grahic Jump Location
Figure 24

Bulk film temperatures along the circumferential direction at the axial center for different external loads, 60krpm, C=35μm

Grahic Jump Location
Figure 25

Rotor radial growths for Case 1 (QE=5Qconv1) over rotor speeds of 10–80krpm

Grahic Jump Location
Figure 26

Rotor temperatures with speeds for different thermal boundary conditions at the rotor end

Grahic Jump Location
Figure 27

Rotor temperatures along the rotor axis for different heat fluxes at the rotor end, 60krpm, C=35μm

Grahic Jump Location
Figure 28

Synchronous direct stiffness coefficients

Grahic Jump Location
Figure 29

Synchronous direct damping coefficients

Tables

Errata

Discussions

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 Journal Articles
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