U.S. patent application number 13/600717 was filed with the patent office on 2014-03-06 for airfoil and method for manufacturing an airfoil.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is Mark Andrew Jones, Harika Senem Kahveci, Aaron Ezekiel Smith. Invention is credited to Mark Andrew Jones, Harika Senem Kahveci, Aaron Ezekiel Smith.
Application Number | 20140064983 13/600717 |
Document ID | / |
Family ID | 50098559 |
Filed Date | 2014-03-06 |
United States Patent
Application |
20140064983 |
Kind Code |
A1 |
Jones; Mark Andrew ; et
al. |
March 6, 2014 |
AIRFOIL AND METHOD FOR MANUFACTURING AN AIRFOIL
Abstract
An airfoil includes a pressure side, a suction side opposed to
the pressure side, a cavity inside the airfoil between the pressure
and suction sides, and a trailing edge downstream from the cavity
between the pressure and suction sides. A first set of cooling
passages through the trailing edge provide fluid communication from
the cavity through the trailing edge. A first divider across each
cooling passage in the first set of cooling passages extends from
the pressure side to the suction side at the trailing edge.
Inventors: |
Jones; Mark Andrew; (Greer,
SC) ; Smith; Aaron Ezekiel; (Simpsonville, SC)
; Kahveci; Harika Senem; (Greenville, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Jones; Mark Andrew
Smith; Aaron Ezekiel
Kahveci; Harika Senem |
Greer
Simpsonville
Greenville |
SC
SC
SC |
US
US
US |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
50098559 |
Appl. No.: |
13/600717 |
Filed: |
August 31, 2012 |
Current U.S.
Class: |
416/97R |
Current CPC
Class: |
F01D 9/041 20130101;
F05D 2240/304 20130101; F05D 2260/202 20130101; F01D 25/12
20130101; F05D 2220/32 20130101; F01D 5/187 20130101 |
Class at
Publication: |
416/97.R |
International
Class: |
F01D 5/18 20060101
F01D005/18 |
Claims
1. An airfoil, comprising: a. a pressure side; b. a suction side
opposed to the pressure side; c. a cavity inside the airfoil
between the pressure and suction sides; d. a trailing edge
downstream from the cavity between the pressure and suction sides;
e. a first set of cooling passages through the trailing edge,
wherein the first set of cooling passages provide fluid
communication from the cavity through the trailing edge; and f. a
first divider across each cooling passage in the first set of
cooling passages, wherein each first divider extends from the
pressure side to the suction side at the trailing edge.
2. The airfoil as in claim 1, further comprising a plurality of
first dividers across each cooling passage in the first set of
cooling passages.
3. The airfoil as in claim 1, further comprising a second set of
cooling passages through the trailing edge, wherein the second set
of cooling passages provide fluid communication from the cavity
through the trailing edge, and the first set of cooling passages
are wider than the second set of cooling passages.
4. The airfoil as in claim 3, further comprising a third set of
cooling passages through the trailing edge, wherein the third set
of cooling passages provide fluid communication from the cavity
through the trailing edge, and the second set of cooling passages
are wider than the third set of cooling passages.
5. The airfoil as in claim 3, further comprising a second set of
pins that extend across each cooling passage in the second set of
cooling passages upstream from the trailing edge.
6. The airfoil as in claim 5, wherein the second set of pins are
axially staggered inside each cooling passage in the second set of
cooling passages.
7. The airfoil as in claim 3, further comprising a second divider
across each cooling passage in the second set of cooling passages,
wherein each second divider extends from the pressure side to the
suction side at the trailing edge.
8. The airfoil as in claim 7, wherein each first divider is wider
than each second divider.
9. The airfoil as in claim 1, wherein the first set of cooling
passages are axially tapered.
10. An airfoil, comprising: a. a pressure side; b. a suction side
opposed to the pressure side; c. a cavity inside the airfoil
between the pressure and suction sides; d. a trailing edge
downstream from the cavity between the pressure and suction sides;
e. a first set of cooling passages through the trailing edge,
wherein the first set of cooling passages provide fluid
communication from the cavity through the trailing edge; and f. a
first set of pins that extend across each cooling passage in the
first set of cooling passages upstream from the trailing edge.
11. The airfoil as in claim 10, wherein the first set of pins are
axially staggered inside each cooling passage in the first set of
cooling passages.
12. The airfoil as in claim 10, further comprising a second set of
cooling passages through the trailing edge, wherein the second set
of cooling passages provide fluid communication from the cavity
through the trailing edge, and the first set of cooling passages
are wider than the second set of cooling passages.
13. The airfoil as in claim 12, further comprising a third set of
cooling passages through the trailing edge, wherein the third set
of cooling passages provide fluid communication from the cavity
through the trailing edge, and the second set of cooling passages
are wider than the third set of cooling passages.
14. The airfoil as in claim 12, further comprising a second set of
pins that extend across each cooling passage in the second set of
cooling passages upstream from the trailing edge.
15. The airfoil as in claim 12, further comprising a second divider
across each cooling passage in the second set of cooling passages,
wherein each second divider extends from the pressure side to the
suction side at the trailing edge.
16. The airfoil as in claim 10, wherein the first set of cooling
passages are axially tapered.
17. An airfoil, comprising: a. a pressure side; b. a suction side
opposed to the pressure side; c. a cavity inside the airfoil
between the pressure and suction sides; d. a trailing edge
downstream from the cavity between the pressure and suction sides;
e. a first set of cooling passages through the trailing edge,
wherein the first set of cooling passages provide fluid
communication from the cavity through the trailing edge; f. a
second set of cooling passages through the trailing edge, wherein
the second set of cooling passages provide fluid communication from
the cavity through the trailing edge, and the first set of cooling
passages are wider than the second set of cooling passages; and g.
first means for reducing flow through the first set of cooling
passages.
18. The airfoil as in claim 17, further comprising second means for
reducing flow through the second set of cooling passages.
19. The airfoil as in claim 17, further comprising a third set of
cooling passages through the trailing edge, wherein the third set
of cooling passages provide fluid communication from the cavity
through the trailing edge, and the second set of cooling passages
are wider than the third set of cooling passages.
20. The airfoil as in claim 17, wherein the first set of cooling
passages are axially tapered.
Description
FIELD OF THE INVENTION
[0001] The present invention generally involves an airfoil and a
method for manufacturing an airfoil.
BACKGROUND OF THE INVENTION
[0002] Turbines are widely used in industrial and commercial
operations. A typical commercial steam or gas turbine used to
generate electrical power includes alternating stages of stationary
and rotating airfoils. For example, stationary vanes may be
attached to a stationary component such as a casing that surrounds
the turbine, and rotating blades may be attached to a rotor located
along an axial centerline of the turbine. A compressed working
fluid, such as but not limited to steam, combustion gases, or air,
flows through the turbine, and the stationary 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 or generating thrust.
[0003] The efficiency of the turbine generally increases with
increased temperatures of the compressed working fluid. However,
excessive temperatures within the turbine may reduce the longevity
of the airfoils in the turbine and thus increase repairs,
maintenance, and outages associated with the turbine. As a result,
various designs and methods have been developed to provide cooling
to the airfoils. For example, a cooling media may be supplied to a
cavity inside the airfoil to convectively and/or conductively
remove heat from the airfoil. In particular embodiments, the
cooling media may flow out of the cavity through cooling passages
in the airfoil to provide film cooling over the outer surface of
the airfoil.
[0004] The cavity and cooling passages in the airfoil may be
manufactured using an investment casting process commonly referred
to as a lost wax process. The lost wax process uses a ceramic core
to define the cavity inside the airfoil. A wax is applied over the
ceramic core, and the wax surface is shaped into the desired
curvature for the airfoil. The wax-covered ceramic core is then
repeatedly dipped into a liquid ceramic solution to create a
ceramic shell over the wax surface. The wax may then be heated to
remove the wax from between the ceramic core and the ceramic shell,
creating a void between the ceramic core and the ceramic shell that
serves as a mold for the airfoil. Molten metal may then be poured
into the mold to form the airfoil. After the metal cools and
solidifies, the ceramic shell may be broken and removed, exposing
the metal that has taken the shape of the void created by the
removal of the wax. The ceramic core may then be dissolved to
produce the airfoil with the cavity and cooling passages.
[0005] Various efforts have been attempted to reduce the amount of
cooling media flowing through the airfoil. For example, reducing
the size and/or width of the cooling passages may enhance heat
transfer to the cooling media while also reducing the amount of
cooling media flowing through the airfoil. However, the smaller
cooling passages require correspondingly smaller projections from
the ceramic core that are sensitive to damage during the casting
process. In particular, the projections from the ceramic core near
either end of the ceramic core are susceptible to breaking off
during casting. In an effort to strengthen the ceramic core while
still providing smaller cooling passages, the projections from the
ceramic core may be larger at either end and narrower in the
middle. However, the larger projections may result in uneven
cooling media flow through the correspondingly larger cooling
passages, depriving the smaller cooling passages in the middle of
the airfoil of sufficient cooling media flow. Accordingly, an
airfoil and method for manufacturing an airfoil that produces a
desired cooling media flow profile through cooling passages in the
airfoil would be useful.
BRIEF DESCRIPTION OF THE INVENTION
[0006] 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.
[0007] One embodiment of the present invention is an airfoil that
includes a pressure side, a suction side opposed to the pressure
side, a cavity inside the airfoil between the pressure and suction
sides, and a trailing edge downstream from the cavity between the
pressure and suction sides. A first set of cooling passages through
the trailing edge provide fluid communication from the cavity
through the trailing edge. A first divider across each cooling
passage in the first set of cooling passages extends from the
pressure side to the suction side at the trailing edge.
[0008] Another embodiment of the present invention is an airfoil
that includes a pressure side, a suction side opposed to the
pressure side, a cavity inside the airfoil between the pressure and
suction sides, and a trailing edge downstream from the cavity
between the pressure and suction sides. A first set of cooling
passages through the trailing edge provide fluid communication from
the cavity through the trailing edge. A first set of pins extend
across each cooling passage in the first set of cooling passages
upstream from the trailing edge.
[0009] The present invention may also include an airfoil having a
pressure side, a suction side opposed to the pressure side, a
cavity inside the airfoil between the pressure and suction sides,
and a trailing edge downstream from the cavity between the pressure
and suction sides. A first set of cooling passages through the
trailing edge provide fluid communication from the cavity through
the trailing edge. A second set of cooling passages through the
trailing edge provide fluid communication from the cavity through
the trailing edge, and the first set of cooling passages are wider
than the second set of cooling passages. The airfoil further
includes first means for reducing flow through the first set of
cooling passages.
[0010] 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
[0011] 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:
[0012] FIG. 1 is a perspective view of an airfoil according to a
first embodiment of the present invention;
[0013] FIG. 2 is a plan view of a core for manufacturing the
airfoil shown in FIG. 1;
[0014] FIG. 3 is a perspective view of an airfoil according to a
second embodiment of the present invention;
[0015] FIG. 4 is a plan view of a core for manufacturing the
airfoil shown in FIG. 3;
[0016] FIG. 5 is a perspective view of an airfoil according to a
third embodiment of the present invention;
[0017] FIG. 6 is a plan view of a core for manufacturing the
airfoil shown in FIG. 5;
[0018] FIG. 7 is a perspective view of an airfoil according to a
fourth embodiment of the present invention;
[0019] FIG. 8 is a plan view of a core for manufacturing the
airfoil shown in FIG. 7; and
[0020] FIG. 9 is an exemplary graph of stresses in the core shown
in FIG. 8.
DETAILED DESCRIPTION OF THE INVENTION
[0021] 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. In addition, the terms "upstream" and "downstream"
refer to the relative location of components in a fluid pathway.
For example, component A is upstream from component B if a fluid
flows from component A to component B. Conversely, component B is
downstream from component A if component B receives a fluid flow
from component A.
[0022] 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.
[0023] Various embodiments of the present invention include an
airfoil and a method for manufacturing an airfoil. The airfoil
generally includes a pressure side having a concave curvature, a
suction side having a convex curvature and opposed to the pressure
side, a cavity inside the airfoil between the pressure and suction
sides, and a trailing edge downstream from the cavity between the
pressure and suction sides. The airfoil further includes one or
more sets of cooling passages through the trailing edge that
provide fluid communication from the cavity through the trailing
edge. One or more of the sets of cooling passages may include
various means for reducing flow through the cooling passages. In
particular embodiments, for example, the means may include one or
more dividers across some of the cooling passages at the trailing
edge. In other particular embodiments, the means may include a set
of pins that extend across some of the cooling passages. Although
exemplary embodiments of the present invention will be described
generally in the context of an airfoil incorporated into a turbine,
one of ordinary skill in the art will readily appreciate from the
teachings herein that embodiments of the present invention are not
limited to a turbine unless specifically recited in the claims.
[0024] Referring now to the drawings, wherein identical numerals
indicate the same elements throughout the figures, FIG. 1 provides
a perspective view of an airfoil 10 according to a first embodiment
of the present invention. As shown in FIG. 1, the airfoil 10
generally includes a pressure side 12 having a concave curvature
and a suction side 14 having a convex curvature and opposed to the
pressure side 12. The pressure and suction sides 12, 14 are
separated from one another to define a cavity 16 inside the airfoil
10 between the pressure and suction sides 12, 14. The cavity 16 may
provide a serpentine or tortuous path for a cooling media to flow
inside the airfoil 10 to remove heat from the airfoil 10. The
airfoil 10 further includes a trailing edge 18 downstream from the
cavity 16 between the pressure and suction sides 12, 14, and a
plurality of cooling passages 20 through the trailing edge 18
provide fluid communication from the cavity 16 through the trailing
edge 18. As used herein, the term "trailing edge" is not limited to
the most downstream portion of the airfoil 10 and may instead also
include portions of the airfoil 10 on the pressure and/or suction
sides 12, 14 that are downstream from the cavity 16.
[0025] The cooling passages 20 may be arranged in multiple sets,
with each set of cooling passages 20 having a different size,
shape, and/or width. For example, a first set of cooling passages
22 located at the top and bottom of the trailing edge 18 may have a
larger size and/or width than a second set of cooling passages 24
located in the middle of the trailing edge 18. In the particular
embodiment shown in FIG. 1, for example, the first set of cooling
passages 22 may include three cooling passages 20 at the top and
three cooling passages 20 at the bottom of the trailing edge 18. As
shown in FIG. 1, each cooling passage 20 may be tapered axially,
and each cooling passage 20 in the first set of cooling passages 22
may have a size and/or width that is approximately three times as
large as each cooling passage 20 in the second set of cooling
passages 24. One of ordinary skill in the art will readily
appreciate from the teachings herein that the number of cooling
passages 20 in the first set of cooling passages 22 may vary
between 1 and 10 or more, and the present invention is not limited
to any particular number of cooling passages 20 in any set of
cooling passages 22, 24 unless specifically recited in the claims.
Similarly, the difference in size, and/or width between the sets of
cooling passages 20 may vary between approximately 1.1 times and 10
times or more, depending on the size of the airfoil 10 and number
of different sets of cooling passages 22, 24 in the airfoil 10, and
the present invention is not limited to any particular difference
in size and/or width of cooling passages 20 unless specifically
recited in the claims.
[0026] The difference in size, shape, and/or width between the
first and second sets of cooling passages 22, 24 would ordinarily
create an undesirable disparity in cooling media flow along the
length of the trailing edge 18. Specifically, the larger size
and/or width of the first set of cooling passages 22 would result
in more cooling media flowing through the first set of cooling
passages 22, possibly resulting in insufficient cooling media flow
through the second set of cooling passages 24. To reduce this
disparity, the first set of cooling passages 22 may further include
means for reducing flow through the first set of cooling passages
22. In the particular embodiment shown in FIG. 1, for example, the
structure associated with the means may include a first divider 30
across each cooling passage 20 in the first set of cooling passages
22. Each first divider 30 is essentially a post, tab, stub, pin, or
similar structure that may extend from the pressure side 12 to the
suction side 14 at the trailing edge 18. As a result, each first
divider 30 may partially obstruct cooling media flow through each
cooling passage 20 in the first set of cooling passages 22 to
reduce any disparity in cooling media flow along the length of the
trailing edge 18. Additionally, the first set of cooling passages
22 may be tapered more than the other cooling passages 20 to reduce
this disparity even further.
[0027] FIG. 2 provides a plan view of a core 40 that may be used to
manufacture the airfoil 10 shown in FIG. 1. As shown in FIG. 2, the
core 40 may include a serpentine portion 42 with a number of long,
thin branches or projections 44 that extend from the serpentine
portion 42. The serpentine portion 42 generally corresponds to the
size and location for the cavity 16 in the airfoil 10, and the
projections 44 generally correspond to the size and location of the
cooling passages 20 through the trailing edge 18. For example, as
shown in FIG. 2, the projections 44 may be grouped into a first set
of projections 46 at the top and bottom of the core 40 that are
approximately three times the size and/or width of the remaining
projections 44 in a second set of projections 48 in the middle of
the core 40. In addition, the first set of projections 46 include
tabs or notches 50 that generally correspond to the location of the
first dividers 30 in the first set of cooling passages 22 described
with respect to FIG. 1. The increased size and/or width of the
first set of projections 46 enhances the durability and resistance
to damage of the projections 44 during the subsequent casting
operations.
[0028] The core 40 may be manufactured from any material having
sufficient strength to withstand the high temperatures associated
with the casting material (e.g., a high alloy metal) while
maintaining tight positioning required for the core 40 during
casting. For example, the core 40 may be cast from ceramic
material, ceramic composite material, or other suitable materials.
Once cast or otherwise manufactured, a laser, electron discharge
machine, drill, water jet, or other suitable device may be used to
refine or form the serpentine portion 42, projections 44, and/or
notches 50 shown in FIG. 2. The core 40 may then be utilized in a
lost wax process as is known in the art. For example, the core 40
may be coated with a wax or other suitable material readily shaped
to the desired thickness and curvature for the airfoil 10. The wax
covered core 40 may then be repeatedly dipped into a liquid ceramic
solution to create a ceramic shell over the wax surface. The wax
may then be heated to remove the wax from between the core 40 and
the ceramic shell, creating a void between the core 40 and the
ceramic shell that serves as a mold for the airfoil 10. Molten
metal may then be poured into the mold to form the airfoil 10.
After the metal cools and solidifies, the ceramic shell may be
broken and removed, exposing the metal that has taken the shape of
the void created by the removal of the wax. The core 40 may then be
dissolved to produce the airfoil 10 with the cavity 16, cooling
passages 20, and first dividers 30 shown in FIG. 1.
[0029] FIG. 3 provides a perspective view of the airfoil 10
according to a second embodiment of the present invention. As shown
in FIG. 3, the airfoil 10 generally includes the pressure side 12,
suction side 14, cavity 16, trailing edge 18, and cooling passages
20 as previously discussed with respect to FIG. 1. In this
particular embodiment, the cooling passages 20 are arranged in
first, second, and third sets of cooling passages 22, 24, 26, with
each set of cooling passages 20 having a different size and/or
width. As shown in FIG. 3, for example, the first set of cooling
passages 22 includes a single cooling passage 20 located at the top
and bottom of the trailing edge 18, the second set of cooling
passages 24 includes a single cooling passage 20 located next to
each cooling passage 20 in the first set of cooling passages 22,
and the third set of cooling passages 26 includes the remaining
cooling passages 20 located in the middle of the trailing edge 18.
In the particular embodiment shown in FIG. 3, each cooling passage
20 may be tapered axially. Each cooling passage 20 in the first set
of cooling passages 22 may have a size and/or width that is
approximately five times as large as each cooling passage 20 in the
third set of cooling passages 26, and each cooling passage 20 in
the second set of cooling passages 24 may have a size and/or width
that is approximately three times as large as each cooling passage
20 in the third set of cooling passages 26. One of ordinary skill
in the art will readily appreciate from the teachings herein that
the number of cooling passages 20 in the first and second sets of
cooling passages 22, 24 may vary between 1 and 10 or more, and the
present invention is not limited to any particular number of
cooling passages 20 in any set of cooling passages 22, 24, 26
unless specifically recited in the claims. Similarly, the
difference in size and/or width between the sets of cooling
passages 22, 24, 26 may vary between approximately 1.1 times and 10
times or more, depending on the size of the airfoil 10 and number
of different sets of cooling passages 22, 24, 26 in the airfoil 10,
and the present invention is not limited to any particular
difference in size, shape, and/or width of cooling passages 20
unless specifically recited in the claims.
[0030] The difference in size, shape, and/or width between the
first, second, and third sets of cooling passages 22, 24, 26 would
ordinarily create an undesirable disparity in cooling media flow
along the length of the trailing edge 18. Specifically, the larger
size and/or width of the first and second sets of cooling passages
22, 24 would result in more cooling media flowing through the first
and second sets of cooling passages 22, 24, possibly resulting in
insufficient cooling media flow through the third set of cooling
passages 26. To reduce this disparity, the first and/or second sets
of cooling passages 22, 24 may further include means for reducing
flow through the respective cooling passages 20. In the particular
embodiment shown in FIG. 3, for example, the structure associated
with the means in the first set of cooling passages 22 may include
multiple first dividers 30 across each cooling passage 20 in the
first set of cooling passages 22. Each first divider 30 is
essentially a post, tab, stub, pin, or similar structure that may
extend from the pressure side 12 to the suction side 14 at the
trailing edge 18. As a result, the multiple first dividers 30 may
partially obstruct cooling media flow through each cooling passage
20 in the first set of cooling passages 22. The structure
associated with the means in the second set of cooling passages 24
may similarly include one or more second dividers 32 across each
cooling passage 20 in the second set of cooling passages 24. The
combination of the means for reducing flow through the first and
second sets of cooling passages 22, 24 reduces any disparity in
cooling media flow along the length of the trailing edge 18.
Additionally, the first and/or second set of cooling passages 22,
24 may be tapered more than the third set of cooling passages 26 to
reduce this disparity even further.
[0031] FIG. 4 provides a plan view of the core 40 that may be used
to manufacture the airfoil 10 shown in FIG. 3. As shown in FIG. 4,
the core 40 may again include the serpentine portion 42,
projections 44, and notches 50 as previously described with respect
to FIG. 2. In the particular embodiment shown in FIG. 4, the
projections 44 are arranged in first, second, and third sets of
projections 46, 48, 49 that correspond to the location and sizes of
the cooling passages 20 in the first, second, and third sets of
cooling passages 22, 24, 26, respectively. Specifically, the first
set of projections 46 include the projections 44 at the top and
bottom of the core 40 that are approximately five times the size
and/or width of the projections 44 in the third set of projections
49. Similarly, the second set of projections 48 include the
projections 44 adjacent to the first set of projections 46 that are
approximately three times the size and/or width of the projections
44 in the third set of projections 49. Lastly, the third set of
projections 49 are located in the middle of the core 40. In
addition, the first and second sets of projections 46, 48 include
the tabs or notches 50 that generally correspond to the location of
the first and second dividers 30, 32 in the first and second sets
of cooling passages 22, 24 described with respect to FIG. 3. The
increased size and/or width of the first and second sets of
projections 46, 48 enhances the durability and resistance to damage
of the projections 44 during the subsequent casting operations.
[0032] FIG. 5 provides a perspective view of the airfoil 10
according to a third embodiment of the present invention, and FIG.
6 provides a plan view of the core 40 for manufacturing the airfoil
10 shown in FIG. 5. As shown in FIGS. 5 and 6, the airfoil 10 and
core 40 generally include the same components as previously
described with respect to the embodiments shown in FIGS. 1-4. In
this particular embodiment, each cooling passage 20 may be tapered
axially. Each cooling passage 20 in the first set of cooling
passages 22 may have a size and/or width that is approximately four
times as large as each cooling passage 20 in the third set of
cooling passages 26, and each cooling passage 20 in the second set
of cooling passages 24 may have a size and/or width that is
approximately three times as large as each cooling passage 20 in
the third set of cooling passages 26. The structure associated with
the means for reducing flow through the cooling passages 20 in the
first and second sets of cooling passages 22, 24 again includes
first and second dividers 30, 32, as previously described with
respect to FIG. 3. However, in the particular embodiment shown in
FIG. 5, each first divider 30 is wider than each second divider 32.
Specifically, each first divider 30 may be wider than each second
divider 32 by approximately 1.1 to 5 times or more, depending on
the particular embodiment. As a result, the wider first dividers 30
may combine with the wider cooling passages 20 in the first set of
cooling passages 22 to reduce any disparity in cooling media flow
along the length of the trailing edge 18. Additionally, the first
and/or second set of cooling passages 22, 24 may be tapered more
than the third set of cooling passages 26 to reduce this disparity
even further.
[0033] As shown most clearly in FIG. 6, the first set of
projections 46 include the projections 44 at the top and bottom of
the core 40 that are approximately four times the size and/or width
of the projections 44 in the third set of projections 49, and the
second set of projections 48 include the projections 44 adjacent to
the first set of projections 46 that are approximately three times
the size and/or width of the projections 44 in the third set of
projections 49. The increased size and/or width of the first and
second sets of projections 46, 48 enhances the durability and
resistance to damage of the projections 44 during the subsequent
casting operations.
[0034] FIG. 7 provides a perspective view of the airfoil 10
according to a fourth embodiment of the present invention, and FIG.
8 provides a plan view of the core 40 for manufacturing the airfoil
10 shown in FIG. 7. Specifically, the airfoil 10 generally includes
the pressure side 12, suction side 14, cavity 16, trailing edge 18,
and cooling passages 20 as previously discussed with respect to
FIG. 1. In this particular embodiment, the first set of cooling
passages 22 includes two cooling passages 20 at the top and bottom
of the trailing edge 18, and the second set of cooling passages 24
includes the cooling passages 20 located in the middle of the
trailing edge 18. Each cooling passage 20 may be tapered axially,
and each cooling passage 20 in the first set of cooling passages 22
may have a size and/or width that is approximately three times as
large as each cooling passage 20 in the second set of cooling
passages 24. The structure associated with the means for reducing
flow through the cooling passages 20 in the first set of cooling
passages 22 may include a first set of pins 60 that extend across
each cooling passage 20 in the first set of cooling passages 22
upstream from the trailing edge 18. The pins 60 may disrupt the
cooling media flow through the cooling passages 20 to reduce the
amount of cooling media flowing through the first set of cooling
passages 22 while also enhancing heat exchange between the airfoil
10 and the cooling media. As shown in the particular embodiment
shown in FIG. 7, one or more of the pins 60 may be axially
staggered inside the cooling passages 20 to further enhance heat
exchange and control cooling media flow through the cooling
passages 20. As a result, the first set of pins 60 may combine with
the wider cooling passages 20 in the first set of cooling passages
22 to reduce any disparity in cooling media flow along the length
of the trailing edge 18. Additionally, the first set of cooling
passages 22 may be tapered more than the second set of cooling
passages 24 to reduce this disparity even further. One of ordinary
skill in the art will readily appreciate from the teachings herein
that in still further embodiments, the means for reducing flow
through the second set of cooling passages 24 shown in FIGS. 3 and
5 may include a second set of pins in each cooling passage 20 in
the second set of cooling passages 24 upstream from the trailing
edge 18, and further illustration of this alternate structure is
not necessary.
[0035] As shown most clearly in FIG. 8, the core 40 may again
include the serpentine portion 42 and projections 44 as previously
described with respect to FIG. 2. In the particular embodiment
shown in FIG. 8, the projections 44 are arranged in first and
second sets of projections 46, 48 that correspond to the location
and sizes of the cooling passages 20 in the first and second sets
of cooling passages 22, 24, respectively. Specifically, the first
set of projections 46 include the two projections 44 at the top and
bottom of the core 40 that are approximately three times the size
and/or width of the projections 44 in the second set of projections
48. In addition, the first set of projections 46 include multiple
holes 62 that generally correspond to the location of the first set
of pins 60 in the first set of cooling passages 22 described with
respect to FIG. 7. The increased size and/or width of the first set
of projections 46 enhances the durability and resistance to damage
of the projections 44 during the subsequent casting operations.
[0036] FIG. 9 provides an exemplary graph of stresses in the core
40 shown in FIG. 8. Specifically, the horizontal axis represents
the ratio of the width of the projections 44 with and without the
pins 60, and the vertical axis represents the ratio of the stress
on the projections with and without pins 60. As shown in FIG. 9,
doubling the width of the projections 44 and adding pins 60 to the
projections reduces the stress across by projections 44 by more
than 50%. For the particular embodiment shown in FIG. 8 in which
the projections 44 in the first set of projections 46 are
approximately three times larger and/or wider than the projections
44 in the second set of projections 48, the stress across the
projections 44 in the first set of projections 46 are calculated to
be less than 20% of the stress across the projections 44 in the
second set of projections 48.
[0037] 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 language of the claims.
* * * * *