Air foil bearing (AFB) technology has made substantial advancement during the past decades and found its applications in various small turbomachinery. However, rotordynamic instability, friction and drag during the start/stop, and thermal management are still challenges for further application of the technology. Hybrid air foil bearing (HAFB), utilizing hydrostatic injection of externally pressurized air into the bearing clearance, is one of the technology advancements to the conventional AFB. Previous studies on HAFBs demonstrate the enhancement in the load capacity at low speeds, reduction or elimination of the friction and wear during starts/stops, and enhanced heat dissipation capability. In this paper, the benefit of the HAFB is further explored to enhance the rotordynamic stability by employing a controlled hydrostatic injection. This paper presents the analytical and experimental evaluation of the rotordynamic performance of a rotor supported by two three-pad HAFBs with the controlled hydrostatic injection, which utilizes the injections at particular locations to control eccentricity and attitude angle. The simulations in both time domain orbit simulations and frequency-domain modal analyses indicate a substantial improvement of the rotor-bearing performance. The simulation results were verified in a high-speed test rig (maximum speed of 70,000 rpm). Experimental results agree with simulations in suppressing the subsynchronous vibrations but with a large discrepancy in the magnitude of the subsynchronous vibrations, which is a result of the limitation of the current modeling approach. However, both simulations and experiments clearly demonstrate the effectiveness of the controlled hydrostatic injection on improving the rotordynamic performance of AFB.

References

References
1.
Valco
,
M. J.
, and
DellaCorte
,
C.
,
2002
, “
Emerging Oil-Free Turbomachinery Technology for Military Propulsion and Power Applications
,”
23rd U.S. Army Science Conference
, Fort Lauderdale, FL, Dec. 2–5.
2.
DellaCorte
,
C.
, and
Edmonds
,
B. J.
,
1995
, “
Preliminary Evaluation of PS300: A New Self-Lubricating High Temperature Composite Coating for Use to 800 C
,” NASA Lewis Research Center, Cleveland, OH, Technical Report No.
NASA-TM-107056
.https://ntrs.nasa.gov/search.jsp?R=19960009064
3.
DellaCorte
,
C.
,
Lukaszewicz
,
V.
, and
Valco
,
M.
,
2000
, “
Performance and Durability of High Temperature Foil Air Bearings for Oil-Free Turbomachinery
,”
STLE Tribol. Trans.
,
43
(
4
), pp.
774
780
.
4.
Stanford
,
M. K.
,
Yanke
,
A. M.
, and
DellaCorte
,
C.
,
2004
, “
Thermal Effects on a Low Cr Modification of PS304 Solid Lubricant Coating
,” NASA Glenn Research Center, Cleveland, OH, Technical Report No.
NASA/TM-2004-213111
.https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040082398.pdf
5.
Feng
,
K.
,
Hu
,
J.
, and
Liu
,
W.
,
2015
, “
Structural Characterization of a Novel Gas Foil Bearing With Nested Compression Springs: Analytical Modeling and Experimental Measurement
,”
ASME J. Eng. Gas Turbines Power
,
138
(
1
), p.
012504
.
6.
Song
,
J.
, and
Kim
,
D.
,
2007
, “
Foil Gas Bearing With Compression Springs: Analyses and Experiments
,”
ASME J. Tribol.
,
129
(
3
), pp.
628
639
.
7.
Ertas
,
B. H.
,
2008
, “
Compliant Hybrid Journal Bearings Using Integral Wire Mesh Dampers
,”
ASME J. Eng. Gas Turbines Power
,
131
(
2
), p. 022503.
8.
San Andrés
,
L.
,
Chirathadam
,
T. A.
, and
Kim
,
T.
,
2010
, “
Measurement of Structural Stiffness and Damping Coefficients in a Metal Mesh Foil Bearing
,”
ASME J. Eng. Gas Turbines Power
,
132
(
3
), p.
032503
.
9.
Feng
,
K.
,
Liu
,
Y.
, and
Zhao
,
X.
,
2015
, “
Experimental Evaluation of the Structure Characterization of a Novel Hybrid Bump-Metal Mesh Foil Bearing
,”
ASME J. Tribol.
,
138
(
2
), p.
021702
.
10.
DellaCorte
,
C.
,
Radil
,
K. C.
, and
Bruckner
,
R. J.
,
2008
, “
Design, Fabrication, and Performance of Open Source Generation I and II Compliant Hydrodynamic Gas Foil Bearings
,”
STLE Tribol. Trans.
,
51
(
3
), pp.
254
264
.
11.
Ku
,
C. R.
, and
Heshmat
,
H.
,
1992
, “
Compliant Foil Bearing Structural Stiffness Analysis: Part I—Theoretical Model Including Strip and Variable Bump Foil Geometry
,”
ASME J. Tribol.
,
114
(
2
), pp.
394
400
.
12.
Radil
,
K.
,
Howard
,
S.
, and
Dykas
,
B.
,
2002
, “
The Role of Radial Clearance on the Performance of Foil Air Bearings
,”
STLE Tribol. Trans.
,
45
(
4
), pp.
485
490
.
13.
Dykas
,
B.
, and
Howard
,
S. A.
,
2004
, “
Journal Design Considerations for Turbomachine Shafts Supported on Foil Air Bearings
,”
STLE Tribol. Trans.
,
47
(
4
), pp.
508
516
.
14.
Shrestha
,
S. K.
,
Kim
,
D.
, and
Kim
,
Y. C.
,
2013
, “
Experimental Feasibility Study of Radial Injection Cooling of Three-Pad Air Foil Bearings
,”
ASME J. Tribol.
,
135
(
4
), p.
041703
.
15.
Radil
,
K.
, and
Batcho
,
Z.
,
2011
, “
Air Injection as a Thermal Management Technique for Radial Foil Air Bearings
,”
STLE Tribol. Trans.
,
54
(
4
), pp.
666
673
.
16.
Kim
,
D.
, and
Park
,
S.
,
2009
, “
Hydrostatic Air Foil Bearings: Analytical and Experimental Investigation
,”
Tribol. Int.
,
42
(
3
), pp.
413
425
.
17.
Kumar
,
M.
, and
Kim
,
D.
,
2008
, “
Parametric Studies on Dynamic Performance of Hybrid Airfoil Bearing
,”
ASME J. Eng. Gas Turbines Power
,
130
(
6
), p.
062501
.
18.
Kumar
,
M.
, and
Kim
,
D.
,
2010
, “
Static Performance of Hydrostatic Air Bump Foil Bearing
,”
Tribol. Int.
,
43
(
4
), pp.
752
758
.
19.
Kim
,
T. H.
, and
San Andrés
,
L.
,
2009
, “
Effect of Side Feed Pressurization on the Dynamic Performance of Gas Foil Bearings: A Model Anchored to Test Data
,”
ASME J. Eng. Gas Turbines Power
,
131
(
1
), p.
012501
.
20.
Horikawa
,
O.
,
Sato
,
K.
, and
Shimokohbe
,
A.
,
1992
, “
An Active Air Journal Bearing
,”
Nanotechnology
,
3
(
2
), pp.
84
90
.
21.
Mizumoto
,
H.
,
Arii
,
S.
, and
Kami
,
Y.
,
1996
, “
Active Inherent Restrictor for Air-Bearing Spindles
,”
Precis. Eng.
,
19
(
2–3
), pp.
141
147
.
22.
San Andrés
,
L.
, and
Ryu
,
K.
,
2008
, “
Hybrid Gas Bearings With Controlled Supply Pressure to Eliminate Rotor Vibrations While Crossing System Critical Speeds
,”
ASME J. Eng. Gas Turbines Power
,
130
(
6
), p.
062505
.
23.
Pierart
,
F. G.
, and
Santos
,
I. F.
,
2016
, “
Adjustable Hybrid Gas Bearing–Influence of Piezoelectrically Adjusted Injection on Damping Factors and Natural Frequencies of a Flexible Rotor Operating Under Critical Speeds
,”
Proc. Inst. Mech. Eng., Part J
,
230
(
10
), pp.
1209
1220
.
24.
Kim
,
D.
,
Lee
,
A. S.
, and
Choi
,
B. S.
,
2014
, “
Evaluation of Foil Bearing Performance and Nonlinear Rotordynamics of 120 kW Oil-Free Gas Turbine Generator
,”
ASME J. Eng. Gas Turbines Power
,
136
(
3
), p.
032504
.
25.
LaTray
,
N.
, and
Kim
,
D.
,
2016
, “
Rotordynamic Performance of a Shaft With Large Overhung Mass Supported by Foil Bearings
,”
ASME J. Eng. Gas Turbines Power
,
139
(
4
), p.
042506
.
26.
Yazdi
,
B. Z.
,
Kim
,
D.
, and
Xu
,
F.
,
2016
, “
Enhancement of the Rotordynamic Performance of a Shaft Supported by Air Foil Bearings With Vibration Damper
,”
ASME
Paper No. GT2016-56790.
27.
Han
,
D.
,
Park
,
S.
, and
Kim
,
W.
,
1994
, “
A Study on the Characteristics of Externally Pressurized Air Bearings
,”
Precis. Eng.
,
16
(
3
), pp.
164
173
.
28.
Mori
,
H.
, and
Miyamatsu
,
Y.
,
1969
, “
Theoretical Flow-Models for Externally Pressurized Gas Bearings
,”
ASME J. Lubr. Technol.
,
91
(
1
), pp.
181
193
.
29.
Gudemane
,
S.
,
2014
, “
Rotordynamic Performance of a Rotor Supported by Three Pad Hybrid Foil Bearings With Controlled Air Injection
,”
M.S. thesis
, The University of Texas at Arlington, Arlington, TX.https://uta-ir.tdl.org/uta-ir/handle/10106/24017
30.
Kim
,
D.
,
2007
, “
Parametric Studies on Static and Dynamic Performance of Air Foil Bearings With Different Top Foil Geometries and Bump Stiffness Distributions
,”
ASME J. Tribol.
,
129
(
2
), pp.
354
364
.
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