U.S. patent application number 13/087253 was filed with the patent office on 2012-10-18 for flexible seal for turbine engine.
This patent application is currently assigned to General Electric Company. Invention is credited to Mark Steven Honkomp, Prashant Shukla, Jalindar Appa Walunj.
Application Number | 20120263580 13/087253 |
Document ID | / |
Family ID | 45954489 |
Filed Date | 2012-10-18 |
United States Patent
Application |
20120263580 |
Kind Code |
A1 |
Shukla; Prashant ; et
al. |
October 18, 2012 |
FLEXIBLE SEAL FOR TURBINE ENGINE
Abstract
A turbine includes a turbine seal. The turbine seal includes a
first straight portion extending along a first axis. The turbine
seal also includes a second straight portion extending along the
first axis. The first and second straight portions of the turbine
seal intersect to form a V-shaped cross section with an opening
extending along the first axis. The first and second straight
portions of the turbine seal are also configured to resiliantly
move towards and away from each other and the first and second
straight portions of the turbine seal are configured to pre-load
the turbine seal along a gap between first and second bucket
segments of the turbine.
Inventors: |
Shukla; Prashant;
(Bangalore, IN) ; Walunj; Jalindar Appa;
(Bangalore, IN) ; Honkomp; Mark Steven; (Taylors,
SC) |
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
45954489 |
Appl. No.: |
13/087253 |
Filed: |
April 14, 2011 |
Current U.S.
Class: |
415/173.3 |
Current CPC
Class: |
Y02T 50/672 20130101;
F16J 15/0887 20130101; F01D 11/006 20130101; Y02T 50/60
20130101 |
Class at
Publication: |
415/173.3 |
International
Class: |
F01D 11/08 20060101
F01D011/08 |
Claims
1. A turbine, comprising: a turbine seal, comprising: a first
straight portion extending along a first axis; and a second
straight portion extending along the first axis, wherein the first
and second straight portions intersect to form a V-shaped cross
section with an opening extending along the first axis, wherein the
first and second straight portions are configured to resiliantly
move towards and away from each other, wherein the first and second
straight portions are configured to pre-load the turbine seal along
a gap between first and second bucket segments of the turbine.
2. The turbine of claim 1, comprising a third straight portion
coupled to the first straight portion and disposed on a first side
of the opening, wherein the third straight portion extends along
the first axis.
3. The turbine of claim 2, comprising a fourth straight portion
coupled to the second straight portion and disposed on a second
side of the opening, wherein the fourth straight portion extends
along the first axis.
4. The turbine of claim 3, wherein the third straight portion and
the fourth straight portion extend in parallel planes along the
first axis.
5. The turbine of claim 3, wherein the third straight portion and
the fourth straight portion each terminate in a flat tip.
6. The turbine of claim 3, wherein the third straight portion and
the fourth straight portion each terminate in a rounded tip.
7. The turbine of claim 1, wherein the turbine seal is configured
to mount within a triangular recess in the first bucket
segment.
8. The turbine of claim 7, comprising the first bucket segment
having the turbine seal disposed in the triangular recess.
9. The turbine of claim 7, wherein the first bucket segment
comprises a channel disposed between an upstream side of the first
turbine segment and the triangular recess.
10. The turbine of claim 1, wherein the turbine seal comprises
material having a first coefficient of thermal expansion that is
greater than a second coefficient of thermal expansion of the first
and second bucket segments.
11. A system, comprising: a first turbine segment comprising a
first blade coupled to a first shank; a second turbine segment
comprising a second blade coupled to a second shank; and a flexible
seal disposed in a gap between the first and second shanks, wherein
the flexible seal comprises an opening formed by a first straight
portion and a second straight portion, the first and second
straight portions diverge at an angle away from a vortex, the first
and second straight portions are configured to resiliantly move
towards and away from each other to vary the width of the opening,
and the flexible seal is configured to maintain contact with the
first and second turbine segments as a width of the opening
varies.
12. The system of claim 11, wherein the first straight portion and
the second straight portion intersect at the vertex to form a
V-shaped cross section.
13. The system of claim 11, wherein the angle between the first and
second straight portions varies to maintain contact between the
flexible seal and the first and second turbine segments as the
width of the opening varies.
14. The system of claim 11, wherein the opening extends along an
axis of the flexible seal.
15. The system of claim 11, wherein the flexible seal extends along
the gap between the first and second shanks in a radial direction
relative to a rotational axis of the first and second turbine
segments, and the flexible seal is at least partially disposed in a
recess in the first shank.
16. The system of claim 15, wherein the recess comprises a
triangular cross-section extending along an axis of the flexible
seal.
17. The system of claim 11, wherein the flexible seal comprises a
third straight portion coupled to the first straight portion and a
fourth straight portion coupled to the second portion.
18. The system of claim 17, wherein the first straight portion and
the second straight portion are at least partially disposed in an
elongated recess in the first shank and the third straight portion
and the fourth straight portion are disposed in the gap.
19. A turbine seal, comprising: a first straight portion extending
along a first axis; a second straight portion extending along the
first axis, wherein the first and second straight portions
intersect to form an opening extending along the first axis,
wherein the first and second straight portions are configured to
pre-load the turbine seal along a gap between first and second
bucket segments of a turbine; a third straight portion coupled to
the first straight portion and disposed on a first side of the
opening, wherein the third straight portion extends along the first
axis; and a fourth straight portion coupled to the second straight
portion and disposed on a second side of the opening, wherein the
fourth straight portion extends along the first axis, wherein the
third straight portion and the fourth straight portion extend in
parallel planes along the first axis.
20. The turbine seal of claim 19, wherein the opening comprises an
angle of between about 70 degrees and about 100 degrees.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to a flexible
seal for use in turbomachinery, such as a turbine engine.
[0002] A gas turbine engine combusts a mixture of fuel and air to
generate hot combustion gases, which in turn drive one or more
turbines. In particular, the hot combustion gases force turbine
bucket segments to rotate, thereby driving a shaft to rotate one or
more loads, e.g., electrical generator. These turbine bucket
segments may include shanks that allow for adjacent placement in a
turbine stage of the gas turbine engine. At the same time, highly
compressed air is often extracted from a compressor for utilization
in pressurizing a cavity formed between two adjacent bucket shanks.
This positive pressure difference may aid in preventing hot
combustion gases from entering into the shank cavity, thus avoiding
increases in thermal stresses that adversely affect bucket life.
However, as these bucket segments and their shanks may be
individually produced and then combined into a single turbine
stage, gaps may be present between the individual turbine bucket
shanks. These gaps may provide a leakage path for the pressurized
shank cavity air, thus reducing overall turbine efficiency and
output. Accordingly, it is desirable to minimize the leakage of
this pressurizing gas through gaps located between turbine bucket
shanks in a turbine stage of a gas turbine engine.
BRIEF DESCRIPTION OF THE INVENTION
[0003] Certain embodiments commensurate in scope with the
originally claimed invention are summarized below. These
embodiments are not intended to limit the scope of the claimed
invention, but rather these embodiments are intended only to
provide a brief summary of possible forms of the invention. Indeed,
the invention may encompass a variety of forms that may be similar
to or different from the embodiments set forth below.
[0004] In a first embodiment, a turbine includes a turbine seal
including a first straight portion extending along a first axis and
a second straight portion extending along the first axis, wherein
the first and second straight portions intersect to form a V-shaped
cross section with an opening extending along the first axis,
wherein the first and second straight portions are configured to
resiliantly move towards and away from each other, wherein the
first and second straight portions are configured to pre-load the
turbine seal along a gap between first and second bucket segments
of the turbine
[0005] In a second embodiment, a system includes a first turbine
segment comprising a first blade coupled to a first shank, a second
turbine segment comprising a second blade coupled to a second
shank, and a flexible seal disposed in a gap between the first and
second shanks, wherein the flexible seal comprises an opening
formed by a first straight portion and a second straight portion,
the first and second straight portions diverge at an angle away
from a vortex, the first and second straight portions are
configured to resiliantly move towards and away from each other to
vary the width of the opening, and the flexible seal is configured
to maintain contact with the first and second turbine segments as a
width of the opening varies.
[0006] In a third embodiment, a turbine seal includes a first
straight portion extending along a first axis, a second straight
portion extending along the first axis, wherein the first and
second straight portions intersect to form a V-shaped cross section
with an opening extending along the first axis, wherein the first
and second straight portions are configured to pre-load the turbine
seal along a gap between first and second bucket segments of a
turbine, a third straight portion coupled to the first straight
portion and disposed on a first side of the opening, wherein the
third straight portion extends along the first axis, and a fourth
straight portion coupled to the second straight portion and
disposed on a second side of the opening, wherein the fourth
straight portion extends along the first axis, wherein the third
straight portion and the fourth straight portion extend in parallel
planes along the first axis.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] These and other features, aspects, and advantages of the
present invention will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
[0008] FIG. 1 is a schematic flow diagram of an embodiment of a gas
turbine engine having turbine bucket platforms with seals;
[0009] FIG. 2 is a side view of an embodiment of two turbine bucket
segments of the gas turbine engine of FIG. 1 taken along line
2-2;
[0010] FIG. 3 is a partial cross-sectional view of two turbine
bucket segments of FIG. 2 taken along line 3-3;
[0011] FIG. 4 is perspective side view of an embodiment of a
flexible seal of FIG. 2;
[0012] FIG. 5 is a partial cross-sectional view of an embodiment of
two turbine bucket segments of FIG. 3 taken within line 5-5,
illustrating an embodiment of the flexible seal;
[0013] FIG. 6 is a partial cross-sectional view of an embodiment of
two turbine bucket segments of FIG. 3 taken within line 5-5,
illustrating an embodiment of the flexible seal; and
[0014] FIG. 7 is a partial cross-sectional view of an embodiment of
two turbine bucket segments of FIG. 3 taken within line 5-5,
illustrating an embodiment of the flexible seal.
DETAILED DESCRIPTION OF THE INVENTION
[0015] One or more specific embodiments of the present invention
will be described below. In an effort to provide a concise
description of these embodiments, all features of an actual
implementation may not be described in the specification. It should
be appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation-specific decisions must be made to achieve the
developers' specific goals, such as compliance with system-related
and business-related constraints, which may vary from one
implementation to another. Moreover, it should be appreciated that
such a development effort might be complex and time consuming, but
would nevertheless be a routine undertaking of design, fabrication,
and manufacture for those of ordinary skill having the benefit of
this disclosure.
[0016] When introducing elements of various embodiments of the
present invention, the articles "a," "an," "the," and "said" are
intended to mean that there are one or more of the elements. The
terms "comprising," "including," and "having" are intended to be
inclusive and mean that there may be additional elements other than
the listed elements.
[0017] The present disclosure is directed to a system and a method
for sealing a gap between adjacent segments in a turbomachine, such
as turbine bucket shanks in a turbine stage of a gas turbine
engine, a steam turbine engine, a hydro turbine engine, or another
turbine. The system and method may include inserting a flexible
seal, such as a flexible seal pin, between adjacent turbine bucket
shanks. The preload value (e.g., spring force) of the flexible seal
and pressure differentials between the turbine bucket shanks
provides a positive seal between any two adjacent bucket shanks.
For example, the preload value of the flexible seal provides a
positive force by the flexible seal against the adjacent bucket
shanks prior to and during operation of the turbomachine (e.g.,
turbine). The pressure differentials also supplement the positive
force of the flexible seal against the adjacent bucket shanks,
thereby increasing the effectiveness of the flexible seal. This
flexible seal may be, for example, V-shaped or formed in other
shapes and may maintain a positive seal despite variations in the
gap between adjacent bucket shanks.
[0018] FIG. 1 is a block diagram of an exemplary turbine system
including a gas turbine engine 10 that may employ turbine rotor
buckets (i.e., blades). As discussed below, the buckets may include
plunger seals, such as V-shaped plunger seals. In certain
embodiments, the engine 10 may be utilized to power an aircraft, a
watercraft, a locomotive, a power generation system, or
combinations thereof. The illustrated gas turbine engine 10
includes fuel nozzles 12, which may intake a fuel supply 14 and mix
the fuel with air, as well as distribute the air-fuel mixture into
a combustor 16. The air-fuel mixture may combust in, for example, a
chamber within combustor 16, thereby creating hot pressurized
exhaust gases. The combustor 16 may direct the exhaust gases
through a turbine 18 toward an exhaust outlet 20. As the exhaust
gases pass through the turbine 18, the gases force turbine blades
to rotate a shaft 21 along an axis of system 10. As illustrated,
shaft 21 is connected to various components of the turbine engine
10, including compressor 22. Compressor 22 also includes blades
coupled to shaft 21. Thus, blades within compressor 22 rotate as
shaft 21 rotates, compressing air from air intake 24 through
compressor 22 into fuel nozzles 12 and/or combustor 16. Shaft 21
may also be connected to load 26, which may be a vehicle or a
stationary load, such as an electrical generator in a power plant
or a propeller on an aircraft. Load 26 may be any suitable device
that is powered by the rotational output of the turbine engine
10.
[0019] FIG. 2 illustrates a side view of an embodiment of two
turbine bucket segments 32 of the turbine 18 portion of the gas
turbine engine 12 taken along line 2-2 of FIG. 1, as well as a
legend that illustrates the orientation of the bucket segments 32
in a radial direction 31, an axial direction 33, and a
circumferential direction 35. The turbine bucket segments 32 may,
for example, be coupled to the shaft 21 via rotor wheels, and may
be partially disposed within the path of the hot combustion gases
as part of a single stage gas turbine, a dual-stage turbine system
that includes a low-pressure turbine and a high-pressure turbine,
or in a multi-stage turbine system with three or more turbine
stages. Alternatively, the turbine bucket segments 32 may be
disposed in a steam turbine or a hydro turbine. For illustrative
purposes, only two turbine bucket segments 32 are illustrated in
FIG. 2; however, it should be noted that multiple turbine bucket
segments 32 may be arranged, for example, to form a circular
structure in the turbine 18.
[0020] The bucket segments 32 may be constructed of a metal, metal
alloy, ceramic matrix composite (CMC), or other suitable material.
Each bucket segment 32 includes a wheel mount 34, a shank 36, a
platform 37, a platform 38, and a bucket or blade 40. When aligned
as illustrated in FIG. 2, the bucket segments 32 may also form a
gap 42 which may allow for gas to leak between the bucket segments
(thus reducing the efficiency of the turbine engine 10) if not
properly sealed. Additionally, in the illustrated embodiment, each
wheel mount 34 includes a dovetail to couple the bucket segment 32
with a corresponding groove (e.g., axial 33 groove) of a rotor
wheel in the turbine 18. Thus, the dovetail of the wheel mount 34
extends into the wheel and the platform 37 rests on the wheel to
support the shank 36. The shank 36 extends radially 31 outward from
the dovetail of the wheel mount 34 to the platform 38, which may be
a ledge or base that supports the bucket or blade 40. For example,
the bucket 40 may be an airfoil extending radially 31 outward from
the platform 38. The buckets 40 (e.g. airfoils) are disposed within
the path of the hot combustion gases. In operation, the hot
combustion gases exert motive forces on the buckets (e.g.,
airfoils) 40 to drive the turbine 18.
[0021] Additionally, as discussed above, the bucket segments 32 may
form a gap 42. This gap 42 may extend radially 31 along the shank
36 from the dovetail of the wheel mount 34 to radially 31 beneath a
damper opening 44, which may be located between the adjacent shanks
36 and radially 31 below the airfoil 40 of each of the bucket
segments 32. This gap 42 may allow for leakage of hot combustion
from an upstream side to a downstream side of the bucket segments
32. Unfortunately, this leakage may reduce the overall efficiency
of the turbine engine 10 during use. Accordingly, it may be
desirable to block this leakage from occurring through the use of,
for example, one or more flexible seals 46 in the gap 42.
[0022] FIG. 3 illustrates a partial cross-sectional view of the
bucket segments 32 taken along line 3-3 of FIG. 2. As illustrated,
the bucket segments 32 are positioned in an annular arrangement
circumferentially 35 adjacent one another, with a cavity 39 formed
therebetween. This cavity 39 may, for example, be a pressurized
cavity that receives compressed air from the compressor 22 cool the
bucket segments 32 and block entry of the hot combustion gases into
the shank cavity 39, thus reducing leakage between bucket segments
32 to increase work of the hot combustion gases on the buckets 40.
However, in this configuration, the shape of the bucket segments 32
may cause the gap 42 (e.g., a leakage path from the cavity 39) to
be present between the adjacent bucket segments 32. That is, the
gap 42 also allow for leakage of the air in the pressurized shank
cavity 39 between the bucket segments 32 if not properly sealed,
for example, by a one or more flexible seals 46 in the gap 42. As
discussed in detail below, the flexible seal 46 may provide a
spring-force or pre-load between the one or more seals 46 and the
segments 32 to ensure a positive seal despite variations in the gap
42.
[0023] FIG. 4 illustrates a perspective side view of an embodiment
of flexible seal 46 (e.g. a V-type seal) that may be utilized for
sealing the gap 42 between bucket segments 32. The flexible seal 46
may, for example, include an elongated structure having a V-shaped
cross-section 47 as well as support legs 48 to define the shape of
the flexible seal 46, wherein the V-shaped cross-section 47 and the
support legs 48 extend along a radial axis 31 of the flexible seal
46. This flexible seal 46 may be a flexible seal pin characterized
as a V-type seal, which includes two straight portions 49 (e.g.,
flat surfaces) that combine to form a V-shape for the flexible seal
46. In other words, the flexible seal 46 may be defined as an
elongated seal with a V-shaped cross-section 47 along its length.
For example, the flexible seal 46 may be an extended V-shape with a
uniform V-shaped cross-section 47 along its length. In certain
embodiments, the flexible seal 46 may be extruded to form the
uniform V-shaped cross-section. Moreover, the support legs 48 may
extend from the uniform V-shaped cross-section along the length of
the flexible seal 46. In one embodiment, the support legs 48 may be
parallel to one another.
[0024] Moreover, the V-shaped cross-section 47 of the flexible seal
46 may compress when pressure is applied. Each of the straight
portions 49 of the flexible seal 46 may flex when pressure is
applied, such that the straight portions 49 may move closer in
proximity to one another (thus moving support legs 48 closer to one
another as well). For example, due to thermal expansion and/or
mechanical load, the shanks 36 may move in a tangential direction,
such as direction 35, reducing gap 42. The inverse may also occur
when a thermal load is reduced, such that gap 42 may increase.
Accordingly, with a change (e.g., reduction) in gap 42, the shank
36 or bucket 32 may apply pressure to the flexible seal 46, causing
the flexible seal 46 to move into a cavity (such as a V-shaped
cavity) in the bucket 32. Conversely, when gap 42 is increased, the
flexible seal 46 may move from a cavity (such as a V-shaped cavity)
in the bucket 32. However, regardless of the change in the gap 42,
the flexible seal 46 will maintain contact with the bucket 32
adjacent the bucket 32 with the cavity therein to maintain a seal
of the gap 42.
[0025] In one embodiment, the flexible seal 46 may be made from
nickel, cobalt, or iron-base superalloys, or other suitable
materials, with desirable mechanical properties able to withstand
turbine operating temperatures and conditions (such as 310
stainless steel). Examples of usable superalloys may include
Inconel.RTM. alloy 600, Inconel.RTM. alloy 625, Inconel.RTM. alloy
718, Inconel.RTM. alloy 738, Inconel.RTM. alloy X-750, or
Hastalloy.RTM. X. The material chosen for the flexible seal 46 may
be based on requirements for mechanical strength, creep resistance
at high temperatures, corrosion resistance, or other attributes.
The flexible seal 46 may be sized such that it fits into the gap
42. An illustration of the flexible seal 46 installed between two
bucket segments 32 is illustrated in FIG. 5.
[0026] FIG. 5 illustrates a cross-sectional view of the bucket
segments 32 taken within line 5-5 of FIG. 3, illustrating an
embodiment of the flexible seal 46 (e.g. a V-type seal). FIG. 5 may
represent assembly conditions (i.e., cold conditions) present for
the bucket segments 32. As illustrated, the flexible seal 46 may be
a flexible seal pin inserted between the bucket segments 32, such
that the flexible seal 46 maintains a positive seal despite
variations in the gap 42 to block leakage of gas along line 50. For
example, the flexible seal 46 may provide a resiliency, a
flexibility, or a spring-force, which creates a pre-load in the gap
42 between the bucket segments 32. In other words, the straight
portions 49 may flex or bend toward one under upon installation in
the gap 42 between the bucket segments 32, such that the straight
portions 49 impart outward forces 51 and 53 toward the adjacent
bucket segments 32. Additionally, support legs 48 may impart an
outward force 54 toward the adjacent bucket segments 32. In this
manner, the flexible seal 46 may be preloaded into position in a
hollow region 56 of one of the bucket segments 32. For example, the
flexible seal 46 may be loaded into a hollow region 56 of one of
the bucket segments 32 that includes two flat portions 58 and 60
configured to receive the flexible seal 46. These flat portions 58
and 60 may form a V-shape 61 or a triangular shape that is sized to
hold the flexible seal 46. In one embodiment, this V-shape 61
formed by flat portions 58 and 60 may be approximately, for
example, 10 mils, 15 mils, 20 mils, 25 mils, 30 mils, or more in
width at its widest opening. However, it should be noted that these
dimensions are given as examples only and that any suitable
dimensions may be applied.
[0027] As illustrated, the flexible seal 46 under assembly (i.e.,
cold) conditions may form an angle 62 separating straight portions
49 of the flexible seal. This angle 62 may be approximately, for
example, 70 degrees, 75 degrees, 80 degrees, 85 degrees, 90
degrees, 95 degrees, 100 degrees, 105 degrees, 110 degrees, 115
degrees, or more. Moreover, the range of the angle 62 may be
between about 60 degrees and about 120 degrees, between about 70
degrees and about 100 degrees, or between about 75 degrees and
about 90 degrees. Furthermore, the hollow region 56 may include an
angle 64 formed at a connection point of the flat portions 58 and
60. This angle 64 may be approximately, for example, 45%, 50%, 55%,
60%, 56%, 70%, or 75% of the angle 62 of the flexible seal 46.
[0028] Furthermore, as illustrated in FIG. 5, under assembly
conditions the flexible seal 46 may operate to seal gap 42, which
may be of a width 66 of approximately 20 mils, 25 mils, 30 mils, 40
mils, 45 mils, 50 mils, or more. That is, the flexible seal 46 may
contact the bucket segment 32 adjacent to the bucket segment 32 in
which cavity 56 is located. Two contact points 68 and 70 of the
support legs 48 of the flexible seal 46 may abut the bucket segment
32, such that the flexible seal 46 may operate to block gas from
moving along line 50 from a frontside 72 (e.g., upstream side
inclusive of the cavity 39) of the bucket segments 32 and a
backside 74 (e.g., downstream side) of the bucket segments 32 to
prevent leakage across gap 42. That is, pressure differentials
between gases present in the frontside 72 and backside 74 of the
bucket segments 32 may exist such that pressure of gases present in
the frontside 78 (e.g., in the cavity 39) of the bucket segments 32
may be greater than those present in the backside 80 of the bucket
segments 32. However, placement of the flexible seal 46 as
illustrated in FIG. 5 may allow for sealing of gap 42 to block the
flow of gas along line 50. Moreover, it is envisioned that the
contact points 68 and 70 may be at the tip of each of the support
legs 48. Additionally, the contact points 68 and 70 may, for
example, be flat, rounded, curved, or otherwise shaped. These
various shapes of the contact points 68 and 70 may be selected
based on such factors as ease of manufacture, frictional resistance
characteristics, or based on other criteria.
[0029] FIG. 6 illustrates a cross-sectional view of the bucket
segments 32 taken within line 5-5 of FIG. 3, illustrating an
embodiment of the flexible seal 46 (e.g. a V-type seal) under
operational conditions (i.e., hot conditions) present for the
bucket segments 32. As illustrated, the flexible seal 46 under
operational (i.e., hot) conditions may form an angle 76 separating
straight portions 49 of the flexible seal. This angle 76 may be
approximately, for example, 30 degrees, 35 degrees, 40 degrees, 45
degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70
degrees, 75 degrees, or more. Moreover, the range of the angle 76
may be between about 30 degrees and about 80 degrees, between about
40 degrees and about 70 degrees, or between about 50 degrees and
about 60 degrees. As illustrated, angle 76 is smaller than angle 62
previously discussed above with respect to FIG. 5. That is, angle
76 may be generated as a result of a width 78 of the gap 42 being
smaller than width 66 of gap 42 in FIG. 5. This reduction in the
value of the width 78 of the gap 42 may be as a result of thermal
expansion of the bucket segments 32 as the temperature increases
due to operation of the engine 10. This thermal expansion causes
the bucket segments 32 to move closer to one another, thus reducing
the width 78 of the gap 42. This thermal expansion also causes the
flexible seal 46 to be pushed further into the hollow region 56,
resulting in support legs 48 moving closer in proximity to one
another. However, the contact points 68 and 70 of the support legs
48 remain in contact with the bucket segment 32 during the
reduction in the width 78 of the gap 42 to block gas from moving
along line 50 from the frontside 72 of the bucket segments 32 to
the backside 74 of the bucket segments 32 (i.e., to block leakage
across gap 42.) In one embodiment, the support legs 48 may move
approximately, for example, approximately 10 mils, 15 mils, 20
mils, 25 mils, 30 mils, or more from their assembly condition
position as the temperature surrounding the flexible seal 46 rises
(e.g., due to the operation of the engine 10.) Additionally, the
flexible seal 46 may return to its original cold assembly position
when the engine 10 is not operating. In this manner, the flexible
seal 46 may adjust its position in response to bucket segment 32
movement caused by, for example, thermal expansion, while
maintaining a seal of the gap 42 present between the bucket
segments 32. Additionally, as the flexible seal 46 is positionally
adjusted, the contact points 68 and 70 constantly maintain contact
with the bucket segment 32. That is, the contact points 68 and 70
have the same amount of contact with the bucket segment 32
regardless of whether the flexible seal 46 is exposed to assembly
conditions or operational conditions.
[0030] FIG. 7 illustrates a cross-sectional view of the bucket
segments 32 taken within line 5-5 of FIG. 3, illustrating an
embodiment of the flexible seal 46 (e.g. a V-type seal) under
operational conditions (i.e., hot conditions) present for the
bucket segments 32. As illustrated, the flexible seal 46 under
operational (i.e., hot) conditions may form an angle 76 separating
straight portions 49 of the flexible seal. Additionally, to aid in
increasing outward forces 51 and 53, high pressure gas present in
the frontside 72 (e.g., upstream side inclusive of the cavity 39)
of the bucket segments 32 may be channeled into hollow region 56 of
one of the bucket segments 32. That is, high pressure gas present
in the frontside 72 (i.e., in the cavity 39) may be directed along
line 80 through a channel 82 of one of the bucket segments 32. That
is, the channel 82 may connect the frontside 72 with the hollow
region 56 of one of the bucket segment 32. This pressurized gas may
aid in imparting additional force to the flexible seal 46 (i.e.,
adding to outward forces 51 and 53, as well as outward force 54) to
aid in the sealing of the gap 42.
[0031] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal language of the claims.
* * * * *