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Research Papers: Gas Turbines: Structures and Dynamics

Mesoscale Foil Gas Bearings for Palm-Sized Turbomachinery: Design, Manufacturing, and Modeling

[+] Author and Article Information
Daejong Kim1

Mechanical and Aerospace Engineering, University of Texas at Arlington, 500 West 1st Street, Arlington, TX 76019daejongkim@uta.edu

Andron Creary

Department of Mechanical Engineering, Texas A&M University, 3123 TAMU, College Station, TX 77843

Suk Sang Chang, Jong Hyun Kim

Pohang Accelerator Laboratory, POSTECH, San-31 Hyojadong, Pohang 790-784, Republic of Korea

1

Corresponding author.

J. Eng. Gas Turbines Power 131(4), 042502 (Apr 10, 2009) (10 pages) doi:10.1115/1.3077643 History: Received December 16, 2007; Revised November 17, 2008; Published April 10, 2009

Palm-sized microturbomachinery have broad potential applications in micropower generation areas, such as air/fuel management systems for various fuel cells, propulsion engine for unmanned micro-air vehicles, power generation turbines for robots, small satellites, etc. This paper introduces design and manufacturing processes of mesoscale foil gas bearings applicable to the microturbomachinery and also presents its performances predicted from nonlinear orbit simulations. X-ray and ultraviolet lithography were explored as promising manufacturing tools of elastic foundations for the mesoscale foil gas bearings. Designed and manufactured mesoscale foil gas bearings have unique design features that precision-machined foil bearings cannot provide, such as easy control of mechanical properties of elastic foundations, a simple assembly process, and easy control of bearing preload through lithographic pattern. The manufactured bearing performance was predicted using a time-domain orbit simulation, and results are presented.

Copyright © 2009 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Schematics of macroscale foil bearing; figure adopted from Ref. 15

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Figure 2

Design of elastic foundation layer for mesoscale foil gas bearings

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Figure 3

Assembly scheme of mesoscale foil gas bearing

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Figure 4

Exaggerated schematic description of elastic foundation with different shell thicknesses along the circumferential direction: (a) front half sub-bearing, and (b) rear half sub-bearing

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Figure 5

Schematic description of the mesoscale foil gas bearing with a hydrodynamic preload in vertical direction; two sub-bearings are arranged as back-to-back configuration

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Figure 6

Photo of an X-ray mask for manufacturing of the mesoscale foil gas bearings. The dark area is the X-ray transparent material (represents the areas for bearing structures) and the bright area is with the X-ray absorber (Au film)

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Figure 7

SEM image of 1 mm thick PMMA mold and the optical image of an elastic foundation layer: (a) PMMA mold, and (b) elastic foundation layer

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Figure 8

Presumed motions of one bump set and equivalent spring-damper models: (a) presumed motions of one bump set, and (b) two spring-damper models for each bump set

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Figure 9

Coordinate systems for analyses. rp is the hydrodynamic preload offset distance.

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Figure 10

Exaggerated description of a top foil sagging effect

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Figure 11

Index for nodal pressures

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Figure 12

Conceptual description of palm-sized gas turbine generator; the arrows indicate bearing locations

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Figure 13

Waterfall plot of simulated vibration in the X-direction for preload offset distance; rp=12 μm, loss factor=0.2

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Figure 14

Waterfall plot of simulated vibration in the X-direction; rp=17 μm, loss factor=0.2

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Figure 15

Waterfall plot in the X-direction at low speeds; rp=17 μm, loss factor=0.2

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Figure 16

Waterfall plot of a simulated vibration in the X-direction; rp=22 μm, loss factor=0.2

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Figure 17

Waterfall plot of simulated vibration in the X-direction; rp=12 μm, loss factor=0.15

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Figure 18

Waterfall plot of a simulated vibration in the X-direction; rp=12 μm, loss factor=0.20

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Figure 19

Waterfall plot of a simulated vibration in the X-direction; rp=12 μm, loss factor=0.25

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Figure 20

Extended waterfall plot of a simulated vibration in the X-direction for speed range 300–380 krpm; rp=12 μm, loss factor=0.25

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