U.S. patent application number 12/574746 was filed with the patent office on 2011-04-07 for radial seal pin.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. Invention is credited to Mark Steven Honkomp, Jalindar Appa Walunj.
Application Number | 20110081245 12/574746 |
Document ID | / |
Family ID | 43734739 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110081245 |
Kind Code |
A1 |
Walunj; Jalindar Appa ; et
al. |
April 7, 2011 |
RADIAL SEAL PIN
Abstract
The present application provides a turbine bucket. The turbine
bucket may include a shank, a radial seal pin slot positioned on
the shank, and a seal pin positioned within the radial seal pin
slot. The seal pin may include a pair of shouldered ends.
Inventors: |
Walunj; Jalindar Appa;
(Bangalore Karnataka, IN) ; Honkomp; Mark Steven;
(Greenville, SC) |
Assignee: |
GENERAL ELECTRIC COMPANY
Schnectady
NY
|
Family ID: |
43734739 |
Appl. No.: |
12/574746 |
Filed: |
October 7, 2009 |
Current U.S.
Class: |
416/179 |
Current CPC
Class: |
F01D 11/005 20130101;
F01D 5/3015 20130101 |
Class at
Publication: |
416/179 |
International
Class: |
F01D 5/22 20060101
F01D005/22 |
Claims
1. A turbine bucket, comprising: a shank; a radial seal pin slot
positioned on the shank; and a seal pin positioned within the
radial seal pin slot; the seal pin comprising a pair of shouldered
ends.
2. The turbine bucket of claim 1, wherein the shank comprises a
pair of radial seal pin slots.
3. The turbine bucket of claim 1, wherein the pair of shouldered
ends comprises a rounded portion and a flat portion.
4. The turbine bucket of claim 1, wherein the seal pin comprises a
first length, the radial seal pin slot comprises a second length,
and wherein the first length is shorter than the second length.
5. The turbine bucket of claim 1, further comprising a pair of
buckets with a gap in between and wherein the seal pin is
positioned in the gap.
6. The turbine bucket of claim 5, wherein the shank comprises a
cover plate with a bucket angle .alpha..
7. The turbine bucket of claim 6, wherein the radial seal pin slot
comprises a seal pocket face with a seal pin bucket angle
.beta..
8. The turbine bucket of claim 7, wherein the radial seal pin slot
comprises an angled corner with an angle .gamma..
9. The turbine bucket of claim 8, wherein the combination of the
angles .alpha., .beta., and .gamma. and a centrifugal force
position the seal pin in the gap.
10. The turbine bucket of claim 1, wherein the shank comprises an
outer diameter gap and an inner diameter gap and wherein the pair
of shouldered ends fill the outer diameter gap and the inner
diameter gap.
11. The turbine bucket of claim 1 wherein the seal pin comprises a
nickel-chromium alloy.
12. A turbine bucket, comprising: a shank; a pair of radial seal
pin slots positioned on the shank; and a seal pin positioned within
each of the pair of radial seal pin slots; the seal pin comprising
a pair of shouldered ends with a rounded portion and a flat
portion.
13. The turbine bucket of claim 12, wherein each of the seal pins
comprises a first length, each of the radial seal pin slots
comprise a second length, and wherein the first length is shorter
than the second length.
14. The turbine bucket of claim 1, further comprising a pair of
buckets with a gap in between and wherein the seal pins are
positioned in the gap.
15. The turbine bucket of claim 14, wherein the shank comprises a
cover plate with a bucket angle .alpha..
16. The turbine bucket of claim 15, wherein the radial seal pin
slots comprise a seal pocket face with a seal pin bucket angle
.beta..
17. The turbine bucket of claim 16, wherein the radial seal pin
slot comprises an angled corner with an angle .gamma..
18. The turbine bucket of claim 17, wherein the combination of the
angles .alpha., .beta., and .gamma. and a centrifugal force
position the seal pins in the gap.
19. The turbine bucket of claim 12, wherein the shank comprises an
outer diameter gap and an inner diameter gap and wherein the pair
of shouldered ends fill the outer diameter gap and the inner
diameter gap.
20. The turbine bucket of claim 12 wherein the seal pin comprises a
nickel-chromium alloy.
Description
TECHNICAL FIELD
[0001] The present application relates generally to gas turbine
engines and more particularly relates to a radial seal pin design
for preventing leakage between gas turbine buckets.
BACKGROUND OF THE INVENTION
[0002] Gas turbines generally include a rotor with a number of
circumferentially spaced blades or buckets. As is known, the
buckets generally include an airfoil, a platform, a shank, a
dovetail, and other elements. The dovetail may be positioned about
a rotor and secured therein. The airfoils project into a hot
combustion gas path produced by a combustor so as to convert the
kinetic energy of the gas into rotational mechanical energy.
[0003] A radial seal pin may be used between the shanks of adjacent
buckets so as to seal against cross-shank leakage with respect to
gas turbines using long shank bucket designs. Generally described,
the pin contacts a seal slot face angle under centrifugal load due
to rotation and slides towards the side seal rails. The slot face
angle forces the pin towards the adjacent bucket so as to prevent
cross-shank leakage between two bucket shank cavities.
[0004] Current issues with such radial seal pins include
mushrooming or flattened ends due to the use of low creep resistant
material, buckling due to inadequate head space, pin binding, pin
lockup, and simple pin wear. Moreover, leakage is still an issue
even with properly functioning pins. Leakage areas include the
shank inside diameter and outside diameter regions. The cross-shank
leakage may lower the purge pressure in the bucket shank cavity.
Such lower purge pressure may lead to possible hot gas ingestion
and subsequent hardware distress.
[0005] There is thus a desire for improved radial seal pin designs
for gas turbines. The improved radial seal pin design should
adequately prevent or limit cross-shank leakage while being durable
and reliable. Such improved sealing should provide improved
cooling, increased bucket life, and overall increased system
performance and efficiency.
SUMMARY OF THE INVENTION
[0006] The present application thus provides a turbine bucket. The
turbine bucket may include a shank, a radial seal pin slot
positioned on the shank, and a seal pin positioned within the
radial seal pin slot. The seal pin may include a pair of shouldered
ends.
[0007] The present application further provides a turbine bucket.
The turbine bucket may include a shank, a pair of radial seal pin
slots positioned on the shank, and a seal pin positioned within
each of the radial seal pin slots. The seal pin may include a pair
of shouldered ends with a rounded portion and a flat portion.
[0008] These and other features and improvements of the present
application will become apparent to one of ordinary skill in the
art upon review of the following detailed description when taken in
conjunction with the several drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic view of a gas turbine engine.
[0010] FIG. 2 is a side view of a known rotor bucket.
[0011] FIG. 3 is a perspective view of a seal pin positioned in the
radial seal pin slot of a rotor bucket.
[0012] FIGS. 4A and 4B are side views of shank leakage areas using
known seal pins.
[0013] FIG. 5 is a perspective view of a radial seal pin slot of a
rotor bucket.
[0014] FIG. 6 is an expanded view of the radial seal pin slot with
a sealing pin therein as is described herein.
[0015] FIG. 7 is a side plan view of the seal pin of FIG. 6.
[0016] FIG. 8 is an expanded view of an end of the seal pin of FIG.
6.
[0017] FIG. 9 is a perspective view of the radial seal pin slot of
FIG. 6.
[0018] FIG. 10 is a further perspective view of the radial seal pin
slot of FIG. 6.
[0019] FIGS. 11A and 11B are side views of shank leakage areas
filled by the seal pin of FIG. 6.
DETAILED DESCRIPTION
[0020] Referring now to the drawings, in which like numbers refer
to like elements throughout the several views, FIG. 1 shows a side
cross-sectional view of a gas turbine engine 10. As is known, the
gas turbine engine 10 may include a compressor 12 to compress an
incoming flow of air. The compressor 12 delivers the compressed
flow of air to a combustor 14. The combustor 14 mixes the
compressed flow of air with a compressed flow of fuel and ignites
the mixture. (Although only a single combustor 14 is shown, the gas
turbine engine 10 may include any number of combustors 14.) The hot
combustion gases are in turn delivered to a turbine 16. The hot
combustion gases drive the turbine 16 so as to produce mechanical
work. The mechanical work produced in the turbine 16 drives the
compressor 12 and an external load such as an electrical generator
and the like.
[0021] The gas turbine engine 10 may use natural gas, various other
types of syngas, and other types of fuels. The gas turbine engine
may be a 9FBA heavy duty gas turbine engine offered by General
Electric Company of Schenectady, N.Y. The gas turbine engine 10 may
have other configurations and may use other types of components.
Other types of gas turbine engines may be used herein. Multiple gas
turbine engines 10, other types of turbines, and other types of
power generation equipment may be used herein together.
[0022] FIG. 2 shows an example of a known rotor bucket 18. As is
known, the rotor bucket 18 may include an airfoil 20 extending from
a platform 22, a shank 24, and a dovetail 26. As described above,
the dovetail 26 may be positioned about a rotor (not shown) and
secured therein for rotation. The shank 24 may include a leading
edge radial seal pin slot 28 and a trailing edge radial seal pin
slot 30. Other rotor bucket designs may be used herein.
[0023] FIG. 3 shows the trailing edge radial seal pin slot 30 with
a known seal pin 32 positioned therein. As is shown, the seal pin
32 generally has rounded ends 33. In this diagram, .alpha. is the
bucket angle, i.e., the angle of a bucket cover plate 34; .beta. is
the seal pin angle, i.e., the angle of a seal pocket top face 35;
F.sub.c is the centrifugal force due to bucket rotation; F.sub.p is
the force normal to the seal pocket top face; F.sub.s is the force
along the seal pocket top; and F.sub.r is the resultant frictional
force. For effective sealing, F.sub.s should be greater than
F.sub.r. Although not shown here, .gamma. is the angle of a seal
pocket corner 36. Generally described, the bucket angle .alpha. and
the seal pocket face angle .beta. accomplish the sideways loading
of the pin 32. Specifically, centrifugal force will force the pin
32 against the seal pocket face 35. The angle .gamma. of the seal
pocket corner 36 then will force the pin 32 tangentially towards an
adjacent bucket 37 so as to fill a gap 39 therebetween.
[0024] FIGS. 4A and 4B show the seal pin 32 positioned between the
rotor bucket 18 and the adjacent bucket 37. FIG. 4A shows an outer
diameter leakage gap 38. The outer diameter leakage gap 38 may be
about equal to the ligament thickness of the top of the seal slots
28, 30. The ligament thickness generally relates to structural
strength limitations. FIG. 4B shows an inner diameter leakage gap
40. The inner diameter leakage gap 40 may be about equal to the
amount of binding tolerance on the seal pin 32. The binding
tolerance generally accounts for different coefficients of thermal
expansion between the seal material and the bucket material as well
as transient operating conditions.
[0025] FIGS. 5 and 6 show a rotor bucket 100 as is described
herein. As described above, the rotor bucket 100 may include an
airfoil 110, a platform 120, a shank 130, and a dovetail 140. The
shank 130 includes a pair of radial seal pin slots 150. Although
only one radial seal pin slot 150 is shown, the shank 130 will
include a leading edge and a trailing edge radial seal pin
slot.
[0026] FIGS. 6 through 8 show a seal pin 160 as may be described
herein. The seal pin 160 may have a first shouldered end 170 and a
second shouldered end 180. As is shown, the shouldered ends 170
have a rounded portion 190 and a flat portion 200. The ends 170,
180 may be largely identical. The pin 160 may be slightly shorter
than the seal pin slot 150 so as to provide for thermal growth and
avoid pin binding.
[0027] The seal pin 160 may be made out of an Inconel 738 material
(a nickel-chromium superalloy) or similar types of material with
sufficient bulk creep strength. The pin 160 may be positioned
within the slots 150 in any orientation. The pin 160 may be used in
any stage of the turbine 16 or elsewhere.
[0028] As is shown in FIGS. 9 and 10, the shank 130 includes the
bucket angle .alpha.. The seal pin slot 150 includes a seal pocket
top face 210 with the angle .beta.. The combination of angles
.alpha. and .beta. make the seal pin 160 move forward under
centrifugal force. Likewise, the radial pin slot 150 includes an
angled corner 250 with the angle .gamma.. The angle .gamma. makes
the seal pin 160 move towards the shank 130 of the next bucket when
the pin 160 moves sideways. Likewise, as shown in FIGS. 11A and
11B, the use of the shoulders 170, 180 fills the outer diameter gap
38 and the inner diameter gap 40 described above for improved
performance.
[0029] Generally described, for determinate sealing:
F.sub.s.gtoreq.F.sub.r
F.sub.c sin(.alpha.+.beta.).gtoreq..mu.F.sub.p
F.sub.c sin(.alpha.+.beta.).gtoreq..mu.F.sub.c
cos(.alpha.+.beta.)
tan(.alpha.+.beta.).gtoreq..mu.
.mu.=0.35
.alpha.+.beta..gtoreq.19.3.degree.
[0030] Likewise, angle .gamma. should be greater than the
frictional angle between the bucket material and the pin material
to prevent pin lock up due to thermal growth during transient
conditions:
F.sub.s.gtoreq.F.sub.r
F sin(.gamma.).gtoreq..mu.F.sub.p
F sin(.gamma.).gtoreq..mu.F cos(.gamma.)
tan(.gamma.).gtoreq..mu.
.mu.=0.35
.gamma..gtoreq.19.3.degree.
[0031] The present application thus provides better sealing between
turbine stage buckets. Specifically, the leakage areas about the
radial seal pins may be substantially reduced. Improved sealing
provides improved efficiency due to low leakage and also may reduce
hot gas ingestion and improve component reliability.
[0032] It should be apparent that the foregoing relates only to
certain embodiments of the present application and that numerous
changes and modifications may be made herein by one of ordinary
skill in the art without departing from the general spirit and
scope of the invention as defined by the following claims and the
equivalents thereof.
* * * * *