In this study, an elastohydrodynamic model was created for predicting the pressure field in a compliant thrust bearing assembly lubricated by high pressure CO2. This application is of significance due to ongoing research into the closed-cycle supercritical CO2 turbine as a high-efficiency alternative to steam turbines. Hardware development for this concept has been led by Sandia National Laboratories, where turbomachinery running on gas foil thrust and journal bearings is being tested. The model accounts for the fluid velocity field, hydrodynamic pressure, and frictional losses within the lubrication layer by evaluating the turbulent Reynolds equation coupled with an equation for structural deformation in the bearings, and the fluid properties database RefProp v9.0. The results of numerical simulations have been compared with empirical correlations, with reasonable agreement attained. Of particular interest is the contrast drawn between the performance of high pressure CO2 as a lubricant, and ambient pressure air. Parametric studies covering a range of fluid conditions, operating speeds, and thrust loads were carried out to illustrate the value of this model as a tool for improved understanding and further development of this nascent technology.

References

References
1.
Angelino
,
G.
,
1967
, “
Perspectives for the Liquid Phase Compression Gas Turbine
,”
ASME J. Eng. Power
,
89
(
2
), pp.
229
237
.10.1115/1.3616657
2.
Dostal
,
V.
,
Driscoll
,
M. J.
, and
Hejzlar
,
P.
,
2004
, “
A Supercritical Carbon Dioxide Cycle for Next Generation Nuclear Reactors
,” MIT-ANP-TR-100.
3.
Conboy
,
T.
, Wright, S., Pasch, J., Fleming, D., Rochau, G., and Fuller, R.,
2012
, “
Performance Characteristics of an Operating Supercritical CO2 Brayton Cycle
,”
ASME J. Eng. Gas Turbines Power
,
134
(
11
), p. 111703.10.1115/1.4007199
4.
DellaCorte
,
C.
, Radil, K., Bruckner, R., and Howard, S.,
2007
, “
Design, Fabrication, and Performance of Open Source Generation I and II Compliant Hydrodynamic Gas Foil Bearings
,” NASA/TM-2007-214691, ARL-TR-4102.
5.
Agrawal
,
G.
,
1997
, “
Foil Air/Gas Bearing Technology—An Overview
,” ASME Paper 97-GT-347.
6.
Wright
,
S.
, Radel, R., Vernon, M., Rochau, G., and Pickard, P.,
2010
, “
Operation and Analysis of a Supercritical CO2 Brayton Cycle
,” SAND2010-0171.
7.
Heshmat
,
H.
, Walowit, J., and Pinkus, O.,
1983
, “
Analysis of Gas-Lubricated Compliant Thrust Bearings
,”
ASME J. Lubr. Technol.
,
105
, pp.
638
646
.10.1115/1.3254696
8.
Iordanoff
,
I.
,
1999
, “
Analysis of an Aerodynamic Compliant Foil Thrust Bearing: Method for a Rapid Design
,”
Trans. ASME
,
121
, pp. 816–822.
9.
Bruckner
,
R.
, DellaCorte, C., and Prahl, J.
2005
, “
Analytic Modeling of Hydrodynamic, Thermal, and Structural Behavior of Foil Thrust Bearings
,” NASA/TM-2005-213811.
10.
Lee
,
D.
, and
Kim.
,
D.
,
2011
, “
Three-Dimensional Thermohydrodynamic Analyses of Rayleigh Step Air Foil Thrust Bearing With Radially Arranged Bump Foils
,”
Tribol. Trans.
,
54
, pp
432
448
.10.1080/10402004.2011.556314
11.
San Andreas
,
L.
, and
Kim
,
T. H.
,
2010
, “
Thermohydrodynamic Analysis of Bump Type Gas Foil Bearings: A Model Anchored to Test Data
,”
ASME J. Eng. Gas Turbines Power
,
132
, p. 042504.
12.
Lee
,
D.
,
Kim
,
D.
, and
Sadashiva
,
R.
,
2011
, “
Transient Thermal Behavior of Preloaded Three-Pad Foil Bearings: Modeling and Experiments
,”
ASME J. Tribol.
,
133
, p. 021703.
13.
Briggs
,
M.
, Prahl, J., Bruckner, R., and Dykas, B.,
2008
, “
High Pressure Performance of Foil Journal Bearings in Various Gases
,”
STLE/ASME 2008 International Joint Tribology Conference
,
Miami, FL
.
14.
Bruckner
,
R.
,
2009
, “
Windage Power Loss in Gas Foil Bearings and the Rotor-Stator Clearance of High Speed Generators Operating in High Pressure Environments
,”
Proceedings of the ASME Turbo Expo 2009
,
Orlando, FL
.
15.
Ng
,
C. W.
, and
Pan
,
C. H. T.
,
1964
, “
A Linearized Turbulent Lubrication Theory
,”
Trans. ASME
,
64
, pp.
675
688
.
16.
Constantinescu
,
V. N.
,
1973
, “
Basic Relationships in Turbulent Lubrication and Their Extension to Include Thermal Effects
,”
ASME J. Lubr. Technol.
, pp.
147
149
.10.1115/1.3451755
17.
Hirs
,
G. G.
,
1973
, “
A Bulk Flow Theory for Turbulence in Lubricant Films
,”
ASME J. Lubr. Technol., pp.
137
146
.10.1115/1.3451752
18.
Heshmat
,
C.
, Xu, D. S., and Heshmat, H.,
2000
, “
Analysis of Gas-Lubricated Foil Thrust Bearings Using Coupled Finite Element and Finite Difference Methods
,”
ASME J. Tribol.
,
122
, pp.
199
204
.10.1115/1.555343
19.
Taylor
,
C.
, and
Dowson
,
D.
,
1974
, “
Turbulent Lubrication Theory—Application to Design
,”
ASME J. Lubr. Technol.
,
96
(
1
), p. 47.10.1115/1.3451907
20.
Peng
,
Z.-C.
, and
Khonsari
,
M. M.
,
2004
, “
Hydrodynamic Analysis of Compliant Foil Bearings With Compressible Air Flow
,”
ASME J. Tribol.
,
126
, pp.
542
546
.10.1115/1.1739242
21.
Peng
,
Z.-C.
, and
Khonsari
,
M. M.
,
2006
, “
A Thermohydrodynamic Analysis of Foil Journal Bearings
,”
ASME J. Tribol.
,
128
, pp.
534
541
.10.1115/1.2197526
22.
Kim
,
T. H.
,
2007
, “
Analysis of Side End Pressurized Bump Type Gas Foil Bearings: A Model Anchored to Test Data
,” Ph.D. Thesis,
Texas A&M University, Texas
.
23.
Lee
,
D.
, and
Kim
,
D.
,
2011
, “
Design and Performance Prediction of Hybrid Air Foil Thrust Bearings
,”
ASME J. Eng. Gas Turbines Power
,
133
, p. 042501.10.1115/1.4002249
24.
Lemmon
,
E. W.
,
Huber
,
M. L.
, and
McLinden
,
M. O.
,
2010
, “
NIST Reference Fluid Thermodynamic and Transport Properties—REFPROP v9.0
,” User's Guide, NIST Standard Reference Database 23.
25.
Span
,
R.
, and
Wagner
,
W.
,
1996
, “
A New Equation of State for Carbon Dioxide Covering the Fluid Region from the Triple-Point Temperature to 1100 K at Pressures up to 800 MPa
,”
J. Phys. Chem.
,
25
(
6
), pp.
1509
1596
.
26.
Kunz
,
O.
,
Klimeck
,
R.
,
Wagner
,
W.
, and
Jaeschke
,
M.
,
2007
, “
The GERG-2004 Wide-Range Equation of State for Natural Gases and Other Mixtures
,” GERG Tech. Monogr. 15, Fortschr.-Ber. VDI, Düsseldorf.
27.
Dykas
,
B.
, Bruckner, R., DellaCorte, C., Edmonds, B., and Prahl, J.
2009
, “
Design, Fabrication, and Performance of Foil Gas Thrust Bearings for Microturbomachinery Applications
,”
ASME J. Eng. Gas Turbines Power
,
131
, p. 012301.10.1115/1.2966418
28.
DellaCorte
,
C.
, and
Valco
,
M.
,
2000
, “
Load Capacity Estimation of Foil Air Journal Bearings for Oil-Free Turbomachinery Applications
,” NASA/TM-2000-209782, ARL-TR-2334.
29.
Dykas
,
B.
,
2006
, “
Factors Influencing the Performance of Foil Gas Thrust Bearings for Oil-Free Turbomachinery Applications
,” Ph.D. Thesis,
Case Western University
,
Ohio
.
30.
DellaCorte
,
C.
, and
Bruckner
,
R.
,
2011
, “
Remaining Technical Challenges and Future Plans for Oil-Free Turbomachinery
,”
ASME J. Eng. Gas Turbines Power
,
133
, p. 042501.10.1115/1.4002271
31.
Pinkus
,
O.
,
1990
,
Thermal Aspects of Fluid Film Tribology
,
ASME
,
New York
.
32.
Conboy
,
T.
, and
Wright
,
S.
,
2011
, “
Modeling of Gas Foil Bearings for Supercritical CO2 Cycle Turbomachinery
,”
Proceedings of the Supercritical CO2 Power Cycle Symposium
.
33.
Schlichting
,
H.
,
1979
,
Boundary Layer Theory
,
7th ed.
,
McGraw-Hill
,
New York
.
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