U.S. patent application number 13/343911 was filed with the patent office on 2013-07-11 for device and method for sealing a gas path in a turbine.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is Kevin Thomas McGovern, Ravichandran Meenakshisundaram, Aaron Gregory Winn. Invention is credited to Kevin Thomas McGovern, Ravichandran Meenakshisundaram, Aaron Gregory Winn.
Application Number | 20130177383 13/343911 |
Document ID | / |
Family ID | 47678512 |
Filed Date | 2013-07-11 |
United States Patent
Application |
20130177383 |
Kind Code |
A1 |
Winn; Aaron Gregory ; et
al. |
July 11, 2013 |
DEVICE AND METHOD FOR SEALING A GAS PATH IN A TURBINE
Abstract
A device for sealing a gas path in a turbine includes a first
shroud segment and a slot in a surface of the first shroud segment.
A barrier extends inside the slot, and a bypass channel in the slot
provides fluid communication between the barrier and the slot to
the gas path in the turbine. A method for sealing a gas path in a
turbine includes placing a barrier between a first slot in a first
shroud segment and a second slot in a second shroud segment and
flowing a fluid between the barrier and the first slot to the gas
path in the turbine, wherein the fluid flows through a first bypass
channel in the first slot.
Inventors: |
Winn; Aaron Gregory;
(Piedmont, SC) ; McGovern; Kevin Thomas;
(Simpsonville, SC) ; Meenakshisundaram; Ravichandran;
(Greenville, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Winn; Aaron Gregory
McGovern; Kevin Thomas
Meenakshisundaram; Ravichandran |
Piedmont
Simpsonville
Greenville |
SC
SC
SC |
US
US
US |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
47678512 |
Appl. No.: |
13/343911 |
Filed: |
January 5, 2012 |
Current U.S.
Class: |
415/1 ;
415/173.1 |
Current CPC
Class: |
F01D 11/005
20130101 |
Class at
Publication: |
415/1 ;
415/173.1 |
International
Class: |
F01D 11/08 20060101
F01D011/08 |
Claims
1. A device for sealing a gas path in a turbine, comprising: a. a
first shroud segment; b. a slot in a surface of said first shroud
segment; c. a barrier extending inside said slot; and d. a bypass
channel in said slot, wherein said bypass channel provides fluid
communication between said barrier and said slot to the gas path in
the turbine.
2. The device as in claim 1, further comprising a second shroud
segment adjacent to said first shroud segment, wherein said first
and second shroud segments have adjacent surfaces.
3. The device as in claim 1, wherein said barrier comprises a
plurality of sections that extends between said slot.
4. The device as in claim 1, wherein said bypass channel extends
substantially perpendicular to a fluid flow in the gas path in the
turbine.
5. The device as in claim 1, wherein said bypass channel comprises
a plurality of uniformly spaced grooves in said slot.
6. The device as in claim 1, wherein said bypass channel has an
arcuate shape.
7. The device as in claim 1, further comprising a fluid port
through said first shroud segment to said slot in said first shroud
segment.
8. A device for sealing a gas path in a turbine, comprising: a. a
first shroud segment, wherein said first shroud segment has a first
slot; b. a second shroud segment adjacent to said first shroud
segment, wherein said second shroud segment has a second slot; c. a
barrier extending from inside said first slot to inside said second
slot, wherein said barrier has a substantially flat surface facing
the gas path and in contact with each of said first and second
slots; and d. a first fluid passage to the gas path in the turbine
between said barrier and said first slot.
9. The device as in claim 8, wherein said barrier has a dimension
that is larger inside said first and second slots than between said
first and second shroud segments.
10. The device as in claim 8, wherein said barrier comprises a
plurality of sections that extend from inside said first slot to
inside said second slot.
11. The device as in claim 8, wherein said first fluid passage
extends in the direction of said second shroud segment.
12. The device as in claim 8, wherein said first fluid passage
comprises a plurality of uniformly spaced grooves in said first
slot.
13. The device as in claim 8, wherein said first fluid passage
comprises a plurality arcuate grooves in said first slot.
14. The device as in claim 8, further comprising a fluid port
through said first shroud segment to said first slot in said first
shroud segment.
15. The device as in claim 8, further comprising a second fluid
passage between said barrier and said second slot to the gas path
in the turbine.
16. A method for sealing a gas path in a turbine, comprising: a.
placing a barrier between a first slot in a first shroud segment
and a second slot in a second shroud segment; and b. flowing a
fluid between said barrier and said first slot to the gas path in
the turbine, wherein said fluid flows through a first bypass
channel in said first slot.
17. The method as in claim 16, further comprising flowing said
fluid through a plurality of grooves in said first slot.
18. The method as in claim 16, further comprising flowing said
fluid through a fluid port in said first shroud segment to said
first slot in said first shroud segment.
19. The method as in claim 16, further comprising flowing the fluid
between said barrier and said second slot to the gas path in the
turbine, wherein said fluid flows through a second bypass channel
in said second slot.
Description
FIELD OF THE INVENTION
[0001] The present disclosure generally involves a device and
method for sealing a gas path in a turbine.
BACKGROUND OF THE INVENTION
[0002] Turbines are widely used in a variety of aviation,
industrial, and power generation applications to perform work. Each
turbine generally includes alternating stages of peripherally
mounted stator vanes and rotating blades. The stator vanes may be
attached to a stationary component such as a casing that surrounds
the turbine, and the rotating blades may be attached to a rotor
located along an axial centerline of the turbine. A compressed
working fluid, such as steam, combustion gases, or air, flows along
a gas path through the turbine to produce work. The stator vanes
accelerate and direct the compressed working fluid onto the
subsequent stage of rotating blades to impart motion to the
rotating blades, thus turning the rotor and performing work.
[0003] Compressed working fluid that leaks around or bypasses the
stator vanes or rotating blades reduces the efficiency of the
turbine. U.S. Pat. No. 4,902,198 describes an apparatus for film
cooling that includes inner and outer shroud segments
circumferentially arranged along a gas path. Strip seals seated in
slots between adjacent shroud segments reduce the amount of
compressed working fluid that escapes from the gas path between
adjacent shroud segments. In addition, holes in the shroud segments
and intermittent reliefs in the strip seals provide a fluid passage
across the strip seals and into the gas path. In this manner, a
pressurized fluid may be supplied through the holes, across the
reliefs, and into the gas path to prevent leakage from the gas path
while also providing film cooling to the strip seals. However, the
reliefs in the strip seals weaken the strip seals, possibly leading
to premature failure, increased maintenance, and/or foreign
material being released into the gas path. As a result, continued
improvements in sealing devices and methods for sealing the gas
path in a turbine would be useful.
BRIEF DESCRIPTION OF THE INVENTION
[0004] Aspects and advantages of the invention are set forth below
in the following description, or may be obvious from the
description, or may be learned through practice of the
invention.
[0005] One embodiment of the present invention is a device for
sealing a gas path in a turbine that includes a first shroud
segment and a slot in a surface of the first shroud segment. A
barrier extends inside the slot, and a bypass channel in the slot
provides fluid communication between the barrier and the slot to
the gas path in the turbine.
[0006] Another embodiment of the present invention is a device for
sealing a gas path in a turbine that includes a first shroud
segment that has a first slot and a second shroud segment adjacent
to the first shroud segment, wherein the second shroud segment has
a second slot. A barrier extends from inside the first slot to
inside the second slot, and the barrier has a substantially flat
surface facing the gas path and in contact with each of the first
and second slots. A first fluid passage to the gas path in the
turbine is between the barrier and the first slot.
[0007] The present invention may also include a method for sealing
a gas path in a turbine. The method includes placing a barrier
between a first slot in a first shroud segment and a second slot in
a second shroud segment and flowing a fluid between the barrier and
the first slot to the gas path in the turbine, wherein the fluid
flows through a first bypass channel in the first slot.
[0008] Those of ordinary skill in the art will better appreciate
the features and aspects of such embodiments, and others, upon
review of the specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] A full and enabling disclosure of the present invention,
including the best mode thereof to one skilled in the art, is set
forth more particularly in the remainder of the specification,
including reference to the accompanying figures, in which:
[0010] FIG. 1 is a side cross-section view of an exemplary turbine
within the scope of the present invention;
[0011] FIG. 2 is an axial cross-section view of adjacent shroud
segments shown in FIG. 1 taken along line A-A according to one
embodiment;
[0012] FIG. 3 is an axial cross-section view of adjacent shroud
segments shown in FIG. 1 taken along line A-A according to an
alternate embodiment;
[0013] FIG. 4 is a side cross-section view of the shroud segment
shown in FIG. 2 taken along line B-B according to one
embodiment;
[0014] FIG. 5 is a side cross-section view of the shroud segment
shown in FIG. 2 taken along line B-B according to an alternate
embodiment; and
[0015] FIG. 6 is a side cross-section view of the shroud segment
shown in FIG. 2 taken along line B-B according to another
embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Reference will now be made in detail to present embodiments
of the invention, one or more examples of which are illustrated in
the accompanying drawings. The detailed description uses numerical
and letter designations to refer to features in the drawings. Like
or similar designations in the drawings and description have been
used to refer to like or similar parts of the invention. As used
herein, the terms "first", "second", and "third" may be used
interchangeably to distinguish one component from another and are
not intended to signify location or importance of the individual
components.
[0017] Each example is provided by way of explanation of the
invention, not limitation of the invention. In fact, it will be
apparent to those skilled in the art that modifications and
variations can be made in the present invention without departing
from the scope or spirit thereof. For instance, features
illustrated or described as part of one embodiment may be used on
another embodiment to yield a still further embodiment. Thus, it is
intended that the present invention covers such modifications and
variations as come within the scope of the appended claims and
their equivalents.
[0018] Various embodiments of the present invention include a
device and method for sealing a gas path in a turbine. In
particular embodiments, a barrier between adjacent shroud segments
may prevent a compressed working fluid from freely flowing between
the shroud segments and out of the gas path. The barrier may extend
from inside slots formed in adjacent surfaces of the shroud
segments. One or more of the shroud segments may include a fluid
port and/or a fluid passage or bypass channel between the barrier
and the slot. A pressurized fluid may be supplied through the fluid
port to flow between the barrier and the slot and into the gas path
to prevent leakage from the gas path while also providing
convective and/or film cooling to the slot and barrier. Although
exemplary embodiments of the present invention will be described
generally in the context of a gas path in a turbine, one of
ordinary skill in the art will readily appreciate that embodiments
of the present invention may be applied to any gas path containing
a pressurized fluid.
[0019] FIG. 1 provides a simplified cross-section view of a portion
of a turbine 10 according to one embodiment of the present
invention. As shown in FIG. 1, the turbine 10 may include
stationary and rotating components surrounded by a casing 12. The
stationary components may include, for example, stationary nozzles
or stator vanes 14 attached to the casing 12. The rotating
components may include, for example, rotating blades 16 attached to
a rotor 18. A working fluid 20, such as steam, combustion gases, or
air, flows along a hot gas path through the turbine 10 from left to
right as shown in FIG. 1. The first stage of stator vanes 14
accelerates and directs the working fluid 20 onto the first stage
of rotating blades 16, causing the first stage of rotating blades
16 and rotor 18 to rotate. The working fluid 20 then flows across
the second stage of stator vanes 14 which accelerates and redirects
the working fluid 20 to the next stage of rotating blades (not
shown), and the process repeats for each subsequent stage.
[0020] As shown in FIG. 1, the radially inward portion of the
casing 12 may include a series of shroud segments 22 connected to
the casing 12 that circumferentially surround and define the hot
gas path to reduce the amount of working fluid 20 that bypasses the
stator vanes 14 or rotating blades 16. As used herein, the terms
"shroud" or "shroud segment" may encompass and include virtually
any static or stationary hardware in the hot gas path exposed to
the temperatures and pressures associated with the working fluid
20. For example, in the particular embodiment shown in FIG. 1, the
shroud segments 22 are located radially outward of the stator vanes
14 and rotating blades 16, while in other particular embodiments
the shroud segments 22 may also be located radially inward of the
stator vanes 14 and/or rotating blades 16.
[0021] FIGS. 2 and 3 provide axial cross-section views of adjacent
shroud segments 22 shown in FIG. 1 taken along line A-A according
to various embodiments of the present invention. In each view, the
shroud segments 22 are located radially outward of the stator vanes
14, and the gas path is below the shroud segments 22 and between
the rotating blades shown in FIGS. 2 and 3. As shown, the shroud
segments 22 have adjacent surfaces 24, and each adjacent surface 24
may have a slot 26, indent, or groove that extends at least
partially into the surface 24. As used herein, the terms "slot",
"indent", and "groove" are meant to be interchangeable and
encompass or include any channel, crevice, notch, or indent defined
in the surface 24 of the shroud segments 22. A barrier 28, seal,
pin, or other structure may be positioned inside the slots 26 and
extend between the slots 26 in the adjacent surfaces 24 to flexibly
hold the shroud segments 22 in place while also minimizing or
preventing working fluid 20 from escaping from the gas path between
the adjacent shrouds 22. The barrier 28 may be formed from ceramic,
alloy steels, or other suitable materials capable of continuous
exposure to the temperatures and pressures associated with the gas
path.
[0022] As shown in both FIGS. 2 and 3, the barrier 28 may have a
substantially flat surface 30 facing the gas path and in contact
with each slot 26. In this manner, the contact between the flat
surface 30 of the barrier 28 and the slot 26 enhances a fluid seal
that reduces and/or prevents the working fluid 20 from escaping or
leaking from the gas path. In the particular embodiment shown in
FIG. 3, the barrier 28 has a dimension 32 that is larger inside the
slots 26 than between the shroud segments 22 to enhance the seal
between the barrier 28 and the slots 26.
[0023] One or more shroud segments 22 may include a fluid port 34
through the shroud segment 22. The fluid port 34 may provide fluid
communication through the shroud segment 22 to the slots 26. In
this manner, a pressurized fluid such as compressed air, an inert
gas, or steam may be supplied through the shroud segment 22 to the
slot 26 to flow over the barrier 28 in the slots 26 and between the
shroud segments 22 to provide convective and/or film cooling.
Alternately or in addition, a fluid passage or bypass channel 36
between the barrier 28 and one or more slots 26 may provide fluid
communication to allow the pressurized fluid to flow past the
barrier 28 and into the gas path. In FIGS. 2 and 3, the fluid
passage or bypass channel 36 is generally illustrated as extending
beneath the barrier 28 substantially perpendicular to a fluid flow
(into the page in FIGS. 2 and 3) in the gas path.
[0024] FIGS. 4-6 provide side cross-section views of the shroud
segment 22 shown in FIG. 2 taken along line B-B to illustrate
various embodiments of the fluid passage or bypass channel 36
within the scope of the present invention. In the particular
embodiment shown in FIG. 4, the fluid passage or bypass channel 36
includes a plurality of uniformly spaced grooves 38 in the slot 26.
The grooves 38 allow the pressurized fluid to flow between the
substantially flat surface 30 of the barrier 28 and the slot 26 to
convectively remove heat from the barrier 28 and/or shroud segment
22. As the pressurized fluid exits the slot 26 of the shroud
segment 22 and enters the gas path, the pressurized fluid provides
a layer of film cooling to the barrier 28 and/or shroud segment 22.
In the particular embodiment shown in FIG. 5, the fluid passage or
bypass channel 36 has an arcuate shape 40 in the slot 26 to reduce
contact points between the barrier 28 and the slot 26, thereby
enhancing convective and film cooling to the barrier 28 as the
pressurized fluid flows between the barrier 28 and the slot 26 and
into the gas path. One of ordinary skill in the art will readily
appreciate that the fluid passage or bypass channel 36 may have
various shapes and sizes, and the present invention is not limited
to any particular shape or size of the fluid passage or bypass
channel 36 unless specifically recited in the claims.
[0025] FIG. 6 illustrates yet another embodiment in which the
barrier 28 includes a plurality of sections 42 that extend
generally parallel between the slots 26 in the adjacent surfaces
24. In addition, the grooves 38 in the fluid passage or bypass
channel 36 have decreasing widths and/or depths in the slot 26 in
the direction of the working fluid 20 flow in the gas path. The
deeper and wider grooves 38 permit additional pressurized fluid to
flow between the barrier 28 and slot 26 to provide additional
convective cooling to the upstream portion of the shroud segments
22 and barrier 28 while also providing increased film cooling
across the barrier 28 and shroud segment 22 as the pressurized
fluid flows into the gas path. The particular width and depth of
the grooves 38 may vary according to the location of the shroud
segments 22 in the gas path.
[0026] The various embodiments shown in FIGS. 1-6 may also provide
a method for sealing the gas path in the turbine 10. The method may
include placing the barrier 28 between slots 26 in adjacent
surfaces 24 of adjacent shroud segments 22 and flowing the
pressurized fluid between the barrier 28 and one or more slots 26
to the gas path in the turbine 10 so that the pressurized fluid
flows through one or more fluid passages or bypass channels 36 in
the one or more slots 26. In particular embodiments, the method may
include flowing the pressurized fluid through the grooves 38 in one
or more slots 26 and/or flowing the pressurized fluid through the
fluid port 34 in one or more shroud segments 22.
[0027] 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 include 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 languages of the claims.
* * * * *