The thrust bearing duty in a pump-turbine generator can be quite arduous, since the pad support system must be symmetrical about the center of the pad, yet the oil-film must converge adequately for either direction of rotation. Special care must be taken with large machines since the thermal and elastic deformation of the pads will increase nonlinearly with size B of the pad, for example, as B2 when thermal deformation is considered. However from first principles, the thickness of the oil film will increase with only the square root of size B½. Poorly shaped films can develop when a design standard is scaled-up to larger sizes. Three options for the thrust bearing design of a particular pump-turbine were considered: (a) “semihard” supports for the pads such as a spring-disk insert, (b) “piston-type” supports in the back of the pads, which are machined to form shallow pistons that fit into recesses, allowing the pads to be supported hydrostatically, and (c) a symmetric arrangement of coil springs. In this instance, an upper limit of thrust bearing temperature was specified. Penalties would incur if this were exceeded. It is shown using a design code (GENMAT) that the best performance is achieved with a spring support (option c), arranged to give a convex film shape in the direction of sliding, and a slightly concave film in the radial direction. This is achieved by limiting the extent of the spring pack in the circumferential direction so that there are unsupported “overhangs” at the lead and trail edges. The radial concavity is arranged by having the spring pack extend edge-to-edge in the radial direction. The bearing has performed very well since commissioning. The original machining patterns are untouched after thousands of reversals under load. The pads appear as new.

References

References
1.
Dabrowski
,
L.
,
Pajaczkowski
,
P.
,
Rotta
,
G.
,
Wasilczuk
,
M.
, and
Wodtke
,
M.
,
2013
, “
Improving Performance of Large Thrust Bearings Through Modeling and Experimentation
,”
Mech. Ind., EDP Sci.
,
14
(4), pp.
267
274
.
2.
Wodtke
,
M.
,
Schubert
,
A.
,
Fillon
,
M.
,
Wasilczuk
,
M.
, and
Pajaczkowski
,
P.
,
2014
, “
Large Hydrodynamic Thrust Bearing: Comparison of the Calculations and Measurements
,”
Proc. Inst. Mech Eng. Part J
,
228
(
9
), pp.
974
983
.
3.
Glavatskih
,
S. B.
, and
Fillon
,
M.
,
2006
, “
Analysis of Thrust Bearings With PTFE-Faced Pads
,”
ASME J. Tribol.
,
128
(
1
), pp.
49
58
.
4.
Ettles
,
C. M.
,
Seyler
,
J.
, and
Bottenschein
,
M.
,
2005
, “
Calculation of a Safety Margin for Hydrogenerator Thrust Bearings
,”
Tribol. Trans.
,
48
(
4
), pp.
450
456
.
5.
Ettles
,
C. M.
,
1980
, “
Size Effects in Tilting Pad Thrust Bearings
,”
Wear
,
59
(
1
), pp.
231
245
.
6.
Yuan
,
X.
,
Zhu
,
J.
,
Chen
,
Z.
,
Wang
,
H.
, and
Zhang
,
C.
,
2003
, “
A Three-Dimensional TEHD Model and an Optimum Surface Profile Design of Pivoted Pad Thrust Bearings With Large Dimensions
,”
Tribol. Trans.
,
46
(
2
), pp.
153
160
.
7.
Ettles
,
C. M.
,
Seyler
,
J.
, and
Bottenschein
,
M.
,
2003
, “
Some Effects of Start-Up and Shut-Down on Thrust Bearing Assemblies in Hydrogenerators
,”
ASME J. Tribol.
,
125
(
4
), pp.
824
832
.
8.
Pajaczkowski
,
P.
,
Schubert
,
A.
,
Wasilczuk
,
M.
, and
Wodtke
,
M.
,
2014
, “
Simulation of Large Thrust Bearing Performance at Transient States, Warm and Cold Start-Up
,”
Proc. Inst. Mech. Eng. Part J
,
228
(
1
), pp.
96
103
.
9.
Gardner
,
W. W.
,
1988
, “
Tilting Pad Thrust Bearing Tests—Influence of Pivot Position
,”
ASME J. Tribol.
,
110
(
4
), pp.
609
613
.
10.
Gardner
,
W. W.
,
1985
, “
Performance Characteristics of Two Tilting Pad Thrust Bearing Designs
,”
JSLE International Tribology Conference
, pp.
61
66
.
11.
Neal
,
P. B.
, and
Soliman
,
M. A. M.
,
1992
, “
The Influence of Pivot Location on the Performance of Tilting-Pad Thrust Bearings
,”
Seminar: Plain Bearings—Energy Efficiency and Design
, Institution of Mechanical Engineers, London, Nov. 10, pp.
45
60
.
12.
Ferguson
,
J.
,
1992
,
1999
, “
Upgrading Thrust Bearings for Hydro Machines
,”
Meeting of Canadian Electrical Association
, Vancouver, Canada.
13.
Glavatskikh
,
S. B.
,
2001
, “
Steady State Performance Characteristics of a Tilting Pad Thrust Bearing
,”
ASME J. Tribol.
,
123
(
3
), pp.
608
615
.
14.
Ettles
,
C. M.
, and
Cameron
,
A.
,
1966
, “
The Action of the Parallel Surface Thrust Bearing
,”
Proc. Inst. Mech. Eng.
,
180
(
11
), pp.
61
75
.
15.
Kawaike
,
K.
,
Okano
,
K.
, and
Furakawa
,
Y.
,
1978
, “
Performance of a Large Thrust Bearing With Minimized Thermal Distortion
,”
ASLE Trans.
,
22
(
2
), pp.
125
134
.
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