U.S. patent application number 13/963322 was filed with the patent office on 2015-02-12 for airfoil for a turbine system.
This patent application is currently assigned to General Electric Company. The applicant listed for this patent is General Electric Company. Invention is credited to John Wesley Harris, JR., Michael James Healy, Stephen Paul Wassynger.
Application Number | 20150044059 13/963322 |
Document ID | / |
Family ID | 52388965 |
Filed Date | 2015-02-12 |
United States Patent
Application |
20150044059 |
Kind Code |
A1 |
Wassynger; Stephen Paul ; et
al. |
February 12, 2015 |
AIRFOIL FOR A TURBINE SYSTEM
Abstract
An airfoil includes a main portion formed of a base material.
Also included is a trailing edge region of the main portion.
Further included is a trailing edge supplement structure comprising
at least one pre-sintered preform (PSP) material operatively
coupled to the base material proximate the trailing edge
region.
Inventors: |
Wassynger; Stephen Paul;
(Simpsonville, SC) ; Harris, JR.; John Wesley;
(Taylors, SC) ; Healy; Michael James; (Greenville,
SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
52388965 |
Appl. No.: |
13/963322 |
Filed: |
August 9, 2013 |
Current U.S.
Class: |
416/97R ;
29/889.1; 416/225; 416/241R |
Current CPC
Class: |
F05D 2240/304 20130101;
F01D 5/187 20130101; F05D 2230/22 20130101; F01D 5/147 20130101;
F01D 5/005 20130101; F05D 2240/122 20130101; F01D 5/186 20130101;
Y10T 29/49318 20150115 |
Class at
Publication: |
416/97.R ;
416/225; 416/241.R; 29/889.1 |
International
Class: |
F01D 5/14 20060101
F01D005/14; F01D 5/00 20060101 F01D005/00 |
Claims
1. An airfoil comprising: a main portion formed of a base material;
a trailing edge region of the main portion; and a trailing edge
supplement structure comprising at least one pre-sintered preform
(PSP) material operatively coupled to the base material proximate
the trailing edge.
2. The airfoil of claim 1, wherein the trailing edge supplement
structure is brazed to the trailing edge region.
3. The airfoil of claim 1, further comprising at least one cooling
channel formed in the base material of the main portion.
4. The airfoil of claim 3, further comprising at least one cooling
passage formed in the trailing edge supplement structure, the at
least one cooling passage in fluid communication with the at least
one cooling channel.
5. The airfoil of claim 1, further comprising a trailing edge
supplement structure aft width and a trailing edge region aft
width, wherein the trailing edge supplement structure aft width is
less than the trailing edge region aft width.
6. The airfoil of claim 1, wherein the at least one PSP material
comprises a first alloy and a second alloy.
7. The airfoil of claim 6, wherein the first alloy and the second
alloy are mixed together at a weight ratio of about 30:70.
8. The airfoil of claim 1, wherein the at least one PSP material
comprises a first PSP material and a second PSP material
operatively coupled together.
9. The airfoil of claim 8, wherein at least one of the first PSP
material and the second PSP material includes a slot, wherein
operative coupling of the first PSP material and the second PSP
material forms at least one cooling passage.
10. The airfoil of claim 9, wherein the at least one cooling
passage is in fluid communication with at least one cooling channel
formed in the base material of the main portion.
11. A turbine system comprising: an airfoil; a main portion of the
airfoil extending from a leading edge to a trailing edge and formed
of a base material; a trailing edge supplement structure comprising
a first PSP material and a second PSP material, the first PSP
material and the second PSP material joined to the base material of
the main portion proximate the trailing edge; and at least one
cooling passage within the trailing edge supplement structure.
12. The turbine system of claim 11, wherein at least one of the
first PSP material and the second PSP material includes a slot,
wherein operative coupling of the first PSP material and the second
PSP material forms the at least one cooling passage.
13. The turbine system of claim 11, wherein the at least one
cooling passage is in fluid communication with at least one cooling
channel formed in the base material of the main portion.
14. The turbine system of claim 11, further comprising a trailing
edge supplement structure aft width and a trailing edge region aft
width, wherein the trailing edge supplement structure aft width is
less than the trailing edge region aft width.
15. The turbine system of claim 11, wherein each of the first PSP
material and the second PSP material comprises a first alloy and a
second alloy.
16. The turbine system of claim 15, wherein the first alloy and the
second alloy are mixed together at a weight ratio of about
30:70.
17. A method of repairing a trailing edge region of an airfoil
comprising: removing material proximate the trailing edge region of
the airfoil; exposing a base material of the trailing edge region;
joining at least one PSP material to the base material; and forming
a trailing edge supplement structure upon joining of the at least
one PSP material to the base material.
18. The method of claim 17, further comprising forming at least one
cooling passage within the at least one PSP material prior to
joining the at least one PSP material to the base material.
19. The method of claim 17, further comprising forming at least one
cooling passage within the at least one PSP material after joining
the at least one PSP material to the base material.
20. The method of claim 17, wherein the trailing edge supplement
structure comprises a first PSP material and a second PSP material,
the method further comprising forming at least one cooling passage
within the trailing edge supplement structure by aligning a first
slot of the first PSP material and a second slot of the second PSP
material.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to airfoils, and
more particularly to a trailing edge supplement structure for
airfoils, particularly those in turbine systems.
[0002] Airfoils employed in various turbine systems are formed as
buckets and nozzles. A working fluid such as hot gas or steam is
typically forced across the airfoils, with the buckets coupled to a
rotor of the turbine system. The force of the working fluid on the
buckets causes the buckets, and therefore the coupled body of the
rotor to rotate. As such, aerodynamic geometry of the airfoils
impacts the overall system performance of the turbine system.
Various manufacturing processes, such as casting, may be employed
to form the airfoils, but such processes are limiting in certain
respects, with one limitation relating to the aerodynamic
characteristics of the manufactured airfoils.
[0003] The airfoils are typically formed of nickel, cobalt or
iron-based superalloys with desirable mechanical and environmental
properties for withstanding turbine operating temperatures and
conditions. Because the efficiency of a turbine system is dependent
on its operating temperatures, there is a demand for the airfoils
to be capable of withstanding increasingly higher temperatures. As
the maximum local temperature of a superalloy component approaches
the melting temperature of the superalloy, forced air cooling
becomes necessary. For this reason, airfoils of gas turbine buckets
and nozzles often require complex cooling schemes in which steam or
air, typically bleed air, is forced through internal cooling
passages within the airfoil and then discharged through cooling
holes at the airfoil surface to transfer heat from the component.
As noted above, the processes used to manufacture airfoils is
somewhat limiting and this impacts the cooling passage precision,
with respect to both location and dimension.
BRIEF DESCRIPTION OF THE INVENTION
[0004] According to one aspect of the invention, an airfoil
includes a main portion formed of a base material. Also included is
a trailing edge region of the main portion. Further included is a
trailing edge supplement structure comprising at least one
pre-sintered preform (PSP) material operatively coupled to the base
material proximate the trailing edge region.
[0005] According to another aspect of the invention, a turbine
system includes an airfoil. Also included is a main portion of the
airfoil extending from a leading edge to a trailing edge region and
formed of a base material. Further included is a trailing edge
supplement structure comprising a first PSP material and a second
PSP material, the first PSP material and the second PSP material
joined to the base material of the main portion proximate the
trailing edge region. Yet further included is at least one cooling
passage within the trailing edge supplement structure.
[0006] According to yet another aspect of the invention, a method
of repairing a trailing edge region of an airfoil is provided. The
method includes removing material proximate the trailing edge
region of the airfoil. The method also includes exposing a base
material of the trailing edge region. The method further includes
joining at least one PSP material to the base material. The method
yet further includes forming a trailing edge supplement structure
upon joining of the at least one PSP material to the base
material.
[0007] These and other advantages and features will become more
apparent from the following description taken in conjunction with
the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The subject matter, which is regarded as the invention, is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0009] FIG. 1 is a schematic illustration of a turbine system;
[0010] FIG. 2 is a top plan view of an airfoil;
[0011] FIG. 3 is a cross-sectional view of a trailing edge region
of the airfoil;
[0012] FIG. 4 is a perspective view of a trailing edge supplement
structure; and
[0013] FIG. 5 is a flow diagram illustrating a method of repairing
the trailing edge region of the airfoil.
[0014] The detailed description explains embodiments of the
invention, together with advantages and features, by way of example
with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Referring to FIG. 1, a turbine system 10 constructed in
accordance with an exemplary embodiment of the invention, is
schematically illustrated. The turbine system 10 illustrated
comprises a gas turbine engine, but it is to be appreciated that
embodiments described herein may be employed in alternative
systems, such as a steam turbine, for example. For purposes of
illustration and discussion, the gas turbine engine is
referenced.
[0016] The gas turbine engine 10 includes a compressor section 12
and a plurality of combustor assemblies arranged in a can annular
array, one of which is indicated at 14 and includes a combustion
section 18. It should be appreciated that this invention is
independent of the details of the combustion system, and the can
annular system is referenced for purposes of discussion. Fuel and
compressed air are passed into the combustion section 18 and
ignited to form a high temperature, high pressure combustion
product or air stream that is used to drive a turbine section 24.
The turbine section 24 includes a plurality of stages 26-28 that
are operationally connected to the compressor section 12 through a
rotor 30. In particular, each of the plurality of stages 26-28
includes a nozzle 32 and a bucket 34, with the bucket 34
operatively coupled to the rotor 30. The nozzle 32 and the bucket
34 of each of the plurality of stages 26-28 are airfoils that that
working fluid (e.g., air-fuel mixture) passes over. Although three
stages are identified, one can appreciate that more or less stages
may be present.
[0017] Referring now to FIG. 2, an airfoil 36 representing either
the nozzle 32 or the bucket 34 is illustrated in greater detail.
The airfoil 36 includes a main portion 38 that extends from a
leading edge 40 to a trailing edge region 42. The main portion 38
is formed of a base material that may vary depending on the
particular application. In some embodiments, the base material
comprises a nickel-, cobalt-, or iron-based superalloy. The main
portion 38 may be formed as an equiaxed, directionally solidified
(DS), or single crystal (SX) casting to withstand the high
temperatures and stresses to which it is subjected, such as within
a gas turbine engine, for example. The trailing edge region 42 is
relatively rounded and includes a trailing edge region aft width
44.
[0018] The airfoil 36 also includes a trailing edge supplement
structure 46 that is operatively coupled to the main portion 38
proximate a surface of the trailing edge region 42. As shown,
relative to the main portion 38, the trailing edge supplement
structure 46 tapers to a thinner, more acute end portion, the
dimension referred to herein as a trailing edge supplement
structure aft width 48.
[0019] Referring to FIGS. 3 and 4, the trailing edge region 42 of
the main portion 38 and the trailing edge supplement structure 46
are illustrated in greater detail. In the illustrated embodiment,
the trailing edge supplement structure 46 includes a first PSP
material, referred to herein as a PSP sheet 50 and a second PSP
material, referred to herein as a PSP sheet 52 that are each
pre-sintered preform (PSP) structures. The PSP sheets, namely the
first PSP sheet 50 and the second PSP sheet 52, each comprise a
mixture of particles comprising a first alloy and a second alloy
that have been sintered together at a temperature below their
melting points to form an agglomerate and somewhat porous mass.
Suitable particle size ranges for the powder particles include 150
mesh, or even 325 mesh or smaller to promote rapid sintering of the
particles and reduce porosity in the PSP sheets to about 10 volume
percent or less.
[0020] The first alloy of the first PSP sheet 50 and the second PSP
sheet 52 comprises any composition such as one similar to the base
material of the main portion 38 to promote common physical
properties between the PSP sheets and the main portion 38. For
example, in some embodiments, the first alloy and the base material
share a common composition (i.e., they are the same type of
material). In some embodiments, the first alloy comprises a
nickel-based superalloy or a cobalt-based superalloy. In some
embodiments, the properties for the first alloy include chemical
and metallurgical compatibility with the base material, such as
high fatigue strength, low tendency for cracking, oxidation
resistance and/or machinability.
[0021] The second alloy may also have a composition similar to the
base material of the main portion 38, but further contains a
melting point depressant to promote sintering of the first alloy
and the second alloy particles and enable bonding of the PSP sheets
to the trailing edge region 42 of the main portion 38 at
temperatures below the melting point of the base material. For
example, in some embodiments the melting point depressant comprises
boron and/or silicon.
[0022] The PSP sheets comprise any relative amounts of the first
alloy and the second alloy that are sufficient to provide enough
melting point depressant to ensure wetting and bonding (e.g.,
diffusion/brazing bonding) of the particles of the first alloy and
the second alloy to each other and to the trailing edge region 42
of the main portion 38 of the airfoil 36. For example, in some
embodiments the second alloy comprises at least about 10 weight
percent of each of the first PSP sheet 50 and the second PSP sheet
52. In one embodiment, the second alloy comprises about 70 weight
percent of each of the PSP sheets, with the first alloy comprising
about 30 weight percent of each of the PSP sheets, thereby
resulting in a mixed weight ratio of the first alloy to the second
alloy of about 30:70. In another embodiment, a mixed weight ratio
of the first alloy to the second alloy of about 40:60 is
employed.
[0023] The above-described embodiments of the trailing edge
supplement structure 46 are illustrated and described as having two
PSP sheets. However, it is to be understood that a single PSP sheet
may be employed and operatively coupled to the trailing edge region
42 of the main portion 38. Furthermore, more than two PSP sheets
may be employed to form the trailing edge supplement structure
46.
[0024] Irrespective of the precise number of PSP sheets employed,
the sheet(s) are operatively coupled to the trailing edge region 42
of the main portion 38. In one embodiment, the PSP sheets are
brazed to the trailing edge region 42. The PSP sheets are formed of
materials configured to be brazed to the trailing edge region 42
without the need for application of a braze paste. In this way, the
PSP sheets, such as the first PSP sheet 50 and the second PSP sheet
52, are positioned in a desirable location in an abutting manner
with the trailing edge region 42 within a furnace and heated to a
necessary temperature to facilitate brazing of the PSP sheets to
the main portion 38. In addition to brazing, it is contemplated
that alternative coupling techniques may be employed, including,
but not limited to, welding, diffusion bonding or mechanical
fastening.
[0025] Formation of the PSP sheets as the trailing edge supplement
structure 46 enables thinner trailing edge portions of the airfoil
36, which effectively reduces aerodynamic blockage, thereby
improving overall turbine system performance.
[0026] To provide effective cooling of the airfoil 36, a cooling
arrangement 54 is implemented within the trailing edge region 42 of
the main portion 38 and throughout the trailing edge supplement
structure 46. The trailing edge region 42 of the main portion 38
includes at least one cooling channel 56 that is in fluid
communication with at least one, but typically a plurality of
cooling passages 58 disposed in the trailing edge supplement
structure 46. The plurality of cooling passages 58 may be formed in
a variety of manners and at a variety of times throughout the
manufacturing process. Specifically, the plurality of cooling
passages 58 may be formed prior to coupling of the trailing edge
supplement structure 46 to the main portion 38 or subsequent to
coupling.
[0027] Formation of the plurality of cooling passages 58 prior to
coupling of the trailing edge supplement structure 46 to the main
portion 38 may include formation of negative grooves, slots or the
like into at least one of the PSP sheets during formation of the
PSP sheets themselves, such that the PSP sheets are still in their
pliable green state before initial sintering. The grooves, slots or
the like may be formed in both of the first PSP sheet 50 and the
second PSP sheet 52, such that alignment of the grooves, slots,
etc. is necessary to form the plurality of cooling passages 58.
Alternatively, the plurality of cooling passages 58 may be machined
(i.e., removal of some material from the PSP sheet(s)) via any
suitable material removal operation, including, but not limited to,
milling, grinding, wire electrical discharge machining (EDM),
milled EDM, plunge EDM, electro-chemical machining (ECM), water-jet
trenching, laser trenching, or combinations thereof. It is
contemplated that the material removal process may occur prior to
coupling of the trailing edge supplement structure 46 to the main
portion or after such coupling. Regardless of the time of formation
of the plurality of cooling passages 58, the plurality of cooling
passages 58 are in fluid communication with the at least one
cooling channel 56. It is contemplated that the above-described
embodiments may be incorporated into new or existing airfoils of
various turbine systems.
[0028] As illustrated in the flow diagram of FIG. 5, and with
reference to FIGS. 1-4, a method of repairing a trailing edge
region of an airfoil 100 is also provided. The turbine system 10
and the trailing edge supplement structure 46 of the airfoil 36
have all been previously described and specific structural
components need not be described in further detail. The method of
repairing a trailing edge region of an airfoil 100 includes
removing material proximate the trailing edge region of the airfoil
102. A base material of the trailing edge region is exposed 104 and
at least one PSP sheet is joined to the base material 106. A
trailing edge supplement structure is formed upon joining of the at
least one PSP sheet to the base material 108. The method of
repairing a trailing edge region of an airfoil 100 also includes
forming at least one cooling passage that is in fluid communication
with the at least one cooling channel 56 of the main portion 38, as
described in detail above.
[0029] While the invention has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the invention is not limited to such
disclosed embodiments. Rather, the invention can be modified to
incorporate any number of variations, alterations, substitutions or
equivalent arrangements not heretofore described, but which are
commensurate with the spirit and scope of the invention.
Additionally, while various embodiments of the invention have been
described, it is to be understood that aspects of the invention may
include only some of the described embodiments. Accordingly, the
invention is not to be seen as limited by the foregoing
description, but is only limited by the scope of the appended
claims.
* * * * *