0
Research Papers: Gas Turbines: Structures and Dynamics

Parametric Studies on Dynamic Performance of Hybrid Airfoil Bearing

[+] Author and Article Information
Manish Kumar

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

Daejong Kim1

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

1

Corresponding author.

J. Eng. Gas Turbines Power 130(6), 062501 (Aug 21, 2008) (8 pages) doi:10.1115/1.2940354 History: Received November 25, 2007; Revised March 08, 2008; Published August 21, 2008

Airfoil bearings offer many advantages over oil-lubricated bearings, but they have reliability issues during start∕stops (wear) and limited heat dissipation capability. To address these issues, a hybrid airfoil bearing (HAFB) combining hydrodynamic airfoil bearing with hydrostatic lift was introduced previously by one of the authors of this paper. Their studies show that HAFB has superior performance compared to its hydrodynamic counterpart in load capacity and cooling performance. In this article, the bearing stiffness and damping coefficients of HAFB are calculated using a linear perturbation method developed for HAFB. Simulations showed that feed parameter and supply pressure affect the dynamic characteristics of HAFB. With an increase in either the supply pressure or the feed parameter, the rotor centers itself and hence one sees a decrease in direct stiffness. Simulations showed that the cross-coupled stiffness could be reduced by increasing either the supply pressure or the feed parameter. Direct damping showed increasing trend with the supply pressure and the feed parameter. Frequency-domain analysis of the bearing coefficients was also performed. The direct damping showed marginal changes with supply pressure but showed rapid increase with increasing excitation frequencies. The damping converged to null values for all the pressures for supersynchronous excitations. The loss in damping with high stiffness values for high frequency excitation is a typical hardening effect of gas bearings. In almost all the cases, there are rapid decreases in cross-coupled stiffness and damping and the values show converging trends in supersynchronous regime.

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 1

Schematic description of circular HAFB and coordinate system for analysis (a) schematic description of HAFB (b) coordinate system for analysis

Grahic Jump Location
Figure 2

Mesh defined for analysis

Grahic Jump Location
Figure 4

Zeroth order pressure profile, Λ=1.25, and static load 60N

Grahic Jump Location
Figure 5

First order perturbed pressure profile (PX), Λ=1.25, and static load 60N

Grahic Jump Location
Figure 6

Predicted direct stiffness coefficients versus feed parameter (Γs) with increasing supply pressure, Λ=1.25

Grahic Jump Location
Figure 7

Predicted journal eccentricities versus feed parameter (Γs) with increasing supply pressure, Λ=1.25

Grahic Jump Location
Figure 8

Predicted attitude angle versus feed parameter (Γs) with increasing supply pressure, Λ=1.25

Grahic Jump Location
Figure 9

Predicted cross-coupled stiffness coefficients versus feed parameter (Γs) with increasing supply pressure, Λ=1.25

Grahic Jump Location
Figure 10

Predicted direct damping coefficients versus feed parameter (Γs) with increasing supply pressure, Λ=1.25

Grahic Jump Location
Figure 11

Predicted cross-coupled damping coefficients versus feed parameter (Γs) with increasing supply pressure, Λ=1.25

Grahic Jump Location
Figure 12

Predicted direct stiffness coefficients versus excitation frequency ratio with increasing supply pressure, Λ=1.25

Grahic Jump Location
Figure 13

Predicted cross-coupled stiffness coefficients versus excitation frequency ratio with increasing supply pressure, Λ=1.25

Grahic Jump Location
Figure 14

Predicted direct damping versus excitation frequency ratio with increasing supply pressure, Λ=1.25

Grahic Jump Location
Figure 15

Predicted direct stiffness versus excitation frequency ratio with increasing supply pressure, Λ=1.25

Grahic Jump Location
Figure 16

Predicted journal eccentricities versus bearing number (Λ) with increasing supply pressure, Γs=0.6

Grahic Jump Location
Figure 17

Predicted direct stiffness versus bearing number (Λ) with increasing supply pressure, Γs=0.6

Grahic Jump Location
Figure 18

Predicted cross-coupled stiffness versus bearing number (Λ) with increasing supply pressure, Γs=0.6

Grahic Jump Location
Figure 19

Predicted direct damping versus bearing number (Λ) with increasing supply pressure, Γs=0.6

Grahic Jump Location
Figure 20

Predicted cross-coupled damping versus bearing number (Λ) with increasing supply pressure, Γs=0.6

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