Process fluid-lubricated thrust bearings (TBs) in a turbomachine control rotor placement due to axial loads arising from pressure fields on the front shroud and back surface of impellers. To date, prediction of aerodynamic-induced thrust loads is still largely empirical. Thus, needs persist to design and operate proven TBs and to validate predictions of performance derived from often too restrictive computational tools. This paper describes a test rig for measurement of the load performance of water-lubricated hydrostatic/hydrodynamic TBs operating under conditions typical of cryogenic turbo pumps (TPs). The test rig comprises of a rigid rotor composed of a thick shaft and two end collars. A pair of flexure-pivot hydrostatic journal bearings (38 mm in diameter) supports the rotor and quill shaft connected to a drive motor. The test rig hosts two TBs (eight pockets with inner diameter equal to 41 mm and outer diameter equal to 76 mm); one is a test bearing and the other is a slave bearing, both facing the outer side of the thrust collars on the rotor. The slave TB is affixed rigidly to a bearing support. A load system delivers an axial load to the test TB through a nonrotating shaft floating on two aerostatic radial bearings. The test TB displaces to impose a load on the rotor thrust collar, and the slave TB reacts to the applied axial load. The paper presents measurements of the TB operating axial clearance, flow rate, and pocket pressure for conditions of increasing static load (max. 3600 N) and shaft speed to 17.5 krpm (tip speed 69.8 m/s) and for an increasing water supply pressure into the TBs, max. 17.2 bar (250 psig). Predictions from a bulk flow model that accounts for both fluid inertia and turbulence flow effects agree well with recorded bearing flow rates (supply and exiting through the inner diameter), pocket pressure, and ensuing film clearance due to the imposed external load. The measurements and predictions show a film clearance decreasing exponentially as the applied load increases. The bearing flow rate also decreases, and at the highest rotor speed and lowest supply pressure, the bearing is starved of lubricant on its inner diameter side, as predicted. The measured bearing flow rate and pocket pressure aid to the empirical estimation of the orifice discharge coefficient for use in the predictive tool. The test data and validation of a predictive tool give confidence to the integration of fluid film TBs in cryogenic TPs as well as in other more conventional (commercial) machinery. The USAF Upper Stage Engine Technology (USET) program funded the work during the first decade of the 21st century.

References

1.
Minick
,
A.
, and
Peery
,
S.
,
1998
, “
Design and Development of an Advanced Liquid Hydrogen Turbopump
,”
AIAA
Paper No. 98-3681.http://www.dtic.mil/get-tr-doc/pdf?Location=U2&doc=GetTRDoc.pdf&AD=ADA406213
2.
Kurtin
,
K.
,
Childs
,
D.
,
San Andrés
,
L.
, and
Hale
,
K.
,
1993
, “
Experimental Versus Theoretical Characteristics of a High Speed Hybrid (Combination Hydrostatic and Hydrodynamic) Bearing
,”
ASME J. Tribol.
,
115
(
1
), pp.
160
169
.
3.
Franchek
,
N.
,
Childs
,
D.
, and
San Andrés
,
L.
,
1995
, “
Theoretical and Experimental Comparisons for Rotordynamic Coefficients of a High-Speed, High-Pressure, Orifice-Compensated Hybrid Bearings
,”
ASME J. Tribol.
,
117
(
2
), pp.
285
290
.
4.
San Andrés
,
L.
, and
Childs
,
D.
,
1997
, “
Angled Injection—Hydrostatic Bearings, Analysis and Comparison to Test Results
,”
ASME J. Tribol.
,
119
(
1
), pp.
179
187
.
5.
San Andrés
,
L.
,
1992
, “
Analysis of Turbulent Hydrostatic Bearings With a Barotropic Fluid
,”
ASME J. Tribol.
,
114
(
4
), pp.
755
765
.
6.
San Andrés
,
L.
,
1995
, “
Thermohydrodynamic Analysis of Fluid Film Bearings for Cryogenic Applications
,”
AIAA J. Propul. Power
,
11
(
5
), pp.
964
972
.
7.
San Andrés
,
L.
,
1991
, “
Fluid Compressibility Effects on the Dynamic Response of Hydrostatic Journal Bearings
,”
Wear
,
146
(
2
), pp.
269
283
.
8.
Arghir
,
M.
,
Hassini
,
M.-A.
,
Balducchi
,
F.
, and
Gauthier
,
R.
,
2014
, “
Synthesis of Experimental and Theoretical Analysis of Pneumatic Hammer Instability in an Aerostatic Bearing
,”
ASME
Paper No. GT2015-42474.
9.
San Andrés
,
L.
,
2000
, “
Bulk Flow Analysis of Hybrid Thrust Bearings for Process Fluid Applications
,”
ASME J. Tribol.
,
122
(
1
), pp.
170
180
.
10.
San Andrés
,
L.
,
2002
, “
Force and Moment Coefficients for Misaligned Hybrid Thrust Bearings
,”
ASME J. Tribol.
,
124
(
1
), pp.
212
219
.
11.
New
,
N. H.
,
1974
, “
Experimental Comparison of Flooded, Directed, and Inlet Orifice Type of Lubrication for a Tilt Pad Thrust Bearing
,”
ASME J. Lubr. Technol.
,
96
(
1
), pp.
22
27
.
12.
Glavatskih
,
S. B.
,
2002
, “
Laboratory Research Facility for Testing Hydrodynamic Thrust Bearings
,”
J. Eng. Tribol.
,
216
(
2
), pp.
105
116
.
13.
Glavatskih
,
S. B.
, and
DeCamillo
,
S.
,
2004
, “
Influence of Oil Viscosity Grade on Thrust Pad Bearing Operation
,”
J. Eng. Tribol.
,
218
(
5
), pp.
401
412
.
14.
Wang
,
X.
, and
Yamaguchi
,
A.
,
2002
, “
Characteristics of Hydrostatic Bearing/Seal Parts for Water Hydraulic Pumps and Motors. Part 1: Experiment and Theory
,”
Tribol. Int.
,
35
(
7
), pp.
425
433
.
15.
DeCamillo
,
S.
,
2014
, “
Axial Subsynchronous Vibration
,”
43rd Turbomachinery and 30th Pump Users Symposia
(
Pump & Turbo 2014
), Houston, TX, Sept. 23–25.http://turbolab.tamu.edu/proc/turboproc/T43/TurboLecture10.pdf
16.
Belforte
,
G.
,
Colombo
,
F.
,
Raparelli
,
T.
,
Viktorov
,
V.
, and
Trivella
,
A.
,
2006
, “
An Experimental Study of High Speed Rotor Supported by Air Bearings: Test Rig and First Experimental Results
,”
Tribol. Int.
,
39
(
8
), pp.
839
845
.
17.
Belforte
,
G.
,
Colombo
,
F.
,
Raparelli
,
T.
,
Trivella
,
A.
, and
Viktorov
,
V.
,
2011
, “
Comparison Between Grooved and Plane Aerostatic Thrust Bearings: Static Performance
,”
Meccanica
,
46
(
3
), pp.
547
555
.
18.
Aeronautics and Space Engineering Board
,
2012
,
Reusable Booster System: Review and Assessment
, The National Academies Press, Washington, DC.
19.
San Andrés
,
L.
,
2006
, “
Hybrid Flexure Pivot-Tilting Pad Gas Bearings: Analysis and Experimental Validation
,”
ASME J. Tribol.
,
128
(
3
), pp.
551
558
.
20.
San Andrés
,
L.
,
2006
, “
Annular Pressure Seals and Hydrostatic Bearings
,”
Design and Analysis of High Speed Pumps
(RTO-AVT-VKI Lecture Series, Mar. 20–23),
von Karman Institute for Fluid Mechanics
,
Sint-Genesius-Rode, Belgium
, Publication No. RTO-MP-AVT-143.
21.
Wang
,
L.
, and
Jiang
,
S.
,
2014
, “
Centrifugal Effects on the Dynamic Characteristics of High Speed Hydrostatic Thrust Bearing Lubricated by a Low Viscosity Fluid
,”
J. Eng. Tribol.
,
228
(
8
), pp.
860
871
.
22.
San Andrés
,
L.
,
Rohmer
,
M.
, and
Park
,
S.
,
2015
, “
Failure of a Test Rig With Pressurized Gas Bearings: A Lesson on Humility
,”
ASME
Paper No. GT2015-42556.
23.
Forsberg
,
M.
,
2008
, “
Comparison Between Predictions and Experimental Measurements for an Eight Pocket Annular Hydrostatic Thrust Bearing
,” M.S. thesis, Texas A&M University, College Station, TX.
24.
Ramirez
,
F.
,
2008
, “
Comparison Between Predictions and Measurements of Performance Characteristics for an Eight Pocket Hybrid (Combination Hydrostatic/Hydrodynamic) Thrust Bearing
,” M.S. thesis, Texas A&M University, College Station, TX.
25.
Esser
,
P.
,
2010
, “
Measurements Versus Predictions for a Hybrid (Hydrostatic plus Hydrodynamic) Thrust Bearing for a Range of Orifice Diameters
,” M.S. thesis, Mechanical Engineering, College Station, TX.
26.
Childs
,
D.
, and
Esser
,
P.
,
2016
, “
Measurements Versus Predictions for a Hybrid (Hydrostatic Plus Hydrodynamic) Thrust Bearing for a Range of Orifice Diameters
,”
ASME
Paper No. GT2016-56213.
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