U.S. patent application number 10/743516 was filed with the patent office on 2005-06-23 for cooled vane cluster.
Invention is credited to Coons, Todd, Pietraszkiewicz, Edward.
Application Number | 20050135923 10/743516 |
Document ID | / |
Family ID | 34552829 |
Filed Date | 2005-06-23 |
United States Patent
Application |
20050135923 |
Kind Code |
A1 |
Coons, Todd ; et
al. |
June 23, 2005 |
Cooled vane cluster
Abstract
A cast vane cluster with enhanced cooling contains an inner and
an outer platform and at least two airfoils for directing a primary
fluid stream axially rearward. A duct is bounded by inner, an outer
endwall surfaces, and adjacent airfoil fluid directing surfaces.
One or more cooling holes in the duct are drilled using an
electrodischarge machine (EDM) method without a line of sight from
the drilling equipment to the cooling hole location. One or more
cooling holes, located in portions of the duct, may not be visible
when viewed from an external location. Additionally, one or more
cooling holes may only have an outlet cross sectional area visible
when viewed along a longitudinal axis from an external
location.
Inventors: |
Coons, Todd; (Casa Grande,
AZ) ; Pietraszkiewicz, Edward; (Southington,
CT) |
Correspondence
Address: |
PRATT & WHITNEY
400 MAIN STREET
MAIL STOP: 132-13
EAST HARTFORD
CT
06108
US
|
Family ID: |
34552829 |
Appl. No.: |
10/743516 |
Filed: |
December 22, 2003 |
Current U.S.
Class: |
415/115 |
Current CPC
Class: |
F01D 9/041 20130101;
F01D 5/18 20130101; F05D 2230/12 20130101; F05D 2260/202 20130101;
F05D 2230/21 20130101 |
Class at
Publication: |
415/115 |
International
Class: |
F01D 005/14 |
Goverment Interests
[0002] This invention was made with Government support under
N00019-02-C-3003 awarded by the United States Navy. The Government
has certain rights in this invention.
Claims
What is claimed is:
1. A vane cluster comprising: An inner platform including an inner
endwall surface and an inboard cavity; An outer platform including
an outer endwall surface and an outer cavity wherein said outer
platform is spaced radially outboard of said inner platform and
said outer endwall surface faces said inner endwall surface; At
least two airfoils spanning between said inner and outer endwall
surfaces, each including a concave surface, a convex surface, a
leading edge and a trailing edge located axially rearward of said
leading edge, wherein said concave and convex surfaces of adjacent
airfoils face each other; A duct bounded by said adjacent concave
and convex surfaces and said inner and outer endwall surfaces; At
least one hole including an inlet cross sectional area and an
outlet cross sectional area; and wherein said at least one hole
outlet cross sectional area is located on said duct boundary.
2. A vane cluster comprising: An inner platform including an inner
endwall surface and an inboard cavity; An outer platform including
an outer endwall surface and an outer cavity wherein said outer
platform is spaced radially outboard of said inner platform and
said outer endwall surface faces said inner endwall surface; At
least two airfoils spanning between said inner and outer endwall
surfaces, each including a concave surface, a convex surface, a
leading edge and a trailing edge located axially rearward of said
leading edge, wherein said concave and convex surfaces of adjacent
airfoils face each other; A duct bounded by said adjacent concave
and convex surfaces and said inner and outer endwall surfaces; At
least one hole including an inlet cross sectional area and an
outlet cross sectional area; and wherein said at least one hole is
not visible when viewed from a location external of said duct
region.
3. The vane cluster of claim 2 wherein said external location is
axially rearward of said trailing edges.
4. The vane cluster of claim 2 wherein said external location is
axially forward of said leading edges.
5. A vane cluster comprising: An inner platform including an inner
endwall surface and an inboard cavity; An outer platform including
an outer endwall surface and an outer cavity wherein said outer
platform is spaced radially outboard of said inner platform and
said outer endwall surface faces said inner endwall surface; At
least two airfoils spanning between said inner and outer endwall
surfaces, each including a concave surface, a convex surface, a
leading edge and a trailing edge located axially rearward of said
leading edge, wherein said concave and convex surfaces of adjacent
airfoils face each other; A duct bounded by said adjacent concave
and convex surfaces and said inner and outer endwall surfaces; A
duct inlet area bounded by said at least two airfoil leading edges,
said inner endwall surface and said outer endwall surface; A duct
outlet area bounded by said at least two airfoil trailing edges,
said inner endwall surface and said outer endwall surface; At least
one hole including an inlet cross sectional area, an outlet cross
sectional area, a bore extending between said inlet and said outlet
areas wherein said bore has a central, longitudinal axis; and
Wherein said at least one outlet cross sectional area is located on
said duct boundary and said at least one inlet cross sectional area
is not visible when viewed along said longitudinal axis from an
external location.
6. The vane cluster of claim 5 wherein said external location is
located forward of said duct inlet area.
7. The vane cluster of claim 5 wherein said external location is
located rearward of said duct outlet area.
8. The vane cluster of claim 5 further comprising at least one
hollow passage, extending through an airfoil, said at least one
hollow passage, communicating with said inboard and outboard
cavities and forming an internal airfoil surface.
9. The vane cluster of claim 8 wherein said at least one hole inlet
cross sectional area is located on said internal airfoil
surface.
10. The vane cluster of claim 9 wherein said at least one hole is
formed using an electrodischarge machine method.
11. The vane cluster of claim 10 wherein said at least one hole
outlet cross sectional area is circular shaped.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application discloses subject matter related to
co-pending U.S. application "HOLE-DRILLING GUIDE AND METHOD"
(APPLICANT REFERENCE NUMBER EH-10851). The disclosure of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0003] (1) Field of the Invention
[0004] The invention relates to gas turbine engine components, and
more particularly to a cast vane cluster with enhanced cooling.
[0005] (2) Description of the Related Art
[0006] A gas turbine engine includes a compressor for directing a
primary fluid stream axially rearward, through a combustor and into
a turbine. The turbine extracts power from a primary fluid stream
and transmits the power through a shaft to rotate the
forward-mounted compressor. A portion of the primary fluid stream
is also directed to one or more secondary fluid streams for use in
cooling components of the gas turbine engine. Disposed within the
turbine section are alternating, annular stages of rotating blades
and stationary vanes. The blades and vanes are disposed
circumferentially about a central, longitudinal axis of the gas
turbine engine.
[0007] Individual turbine vanes are comprised of an inner platform,
an outer platform and an airfoil spanning radially outward from the
inner platform to the outer platform. The airfoil contains a
forward facing leading edge and a rearward facing trailing edge.
The airfoil is staggered on the platforms in relation to the
primary fluid stream direction, with the airfoil trailing edges of
adjacent vanes forming an overlapping array. Together, the
platforms and airfoils of adjacent vanes bound a duct for directing
the primary fluid stream rearward. An inlet to the duct is bounded
by adjacent airfoil leading edges and inner and outer endwall
surfaces. An outlet to the duct is bounded by adjacent airfoil
trailing edges and inner and outer endwall surfaces. The duct area
generally converges in the axially rearward direction.
[0008] Vanes are typically investment cast of high-strength Nickel
or Cobalt alloys and may contain multiple airfoils within a single
casting. Vane castings with multiple airfoils are referred to as
cast vane clusters and have the advantage of reducing the number of
inter-platform interfaces in a turbine stage. Inter-platform
interfaces are costly to manufacture and are a source of primary
fluid stream leakage, which is detrimental to the operating
efficiency of the gas turbine engine.
[0009] In cast vane clusters requiring cooling, one or more hollow
passages extend through the interior of the airfoils forming a
series of internal airfoil surfaces. The hollow passages direct a
secondary fluid stream into the interior of the cast vane cluster.
A multitude of cooling holes pass through the airfoil walls and
into the hollow passages, allowing the secondary fluid stream to
discharge into the primary fluid stream. Each hole comprises an
inlet, an outlet and a bore extending from the inlet to the outlet
along a central, longitudinal axis. Preferably, the multitude of
cooling holes are drilled from the direction of the airfoil
trailing edge and at an acute angle to the cast vane cluster
surfaces. The drilling direction and angle are necessary to ensure
that the secondary fluid stream is discharged in a substantially
rearward direction. This optimizes the cooling effectiveness of the
secondary fluid stream and reduces aerodynamic losses in the
primary fluid stream.
[0010] Typically, cooling holes are drilled after a vane cluster
casting is made. The standard methods used for drilling cooling
holes in cast articles are laser and electrodischarge machining
(EDM). Laser drilling methods utilize short pulses of a high-energy
beam, an example is shown in U.S. Pat. No. 5,037,183.
Electrodischarge machining (EDM) drilling methods pass an
electrical charge through a gap between an electrode and a surface,
an example is shown in U.S. Pat. No. 6,403,910. Both the laser and
the EDM drilling methods require a line of sight from the drilling
equipment to the hole location, limiting the surfaces that may be
drilled.
[0011] Due to the stagger of the airfoils on the platforms of a
cast vane cluster, portions of the duct surfaces are obstructed by
the airfoil trailing edges and cannot be drilled using conventional
laser or EDM drilling methods. The durability of cast vane clusters
would be vastly improved if cooling holes could be placed wherever
needed on the duct surfaces. What is needed is a cast vane cluster
with cooling holes drilled into portions of the duct without a line
of sight from the drilling equipment to the hole location.
BRIEF SUMMARY OF THE INVENTION
[0012] Provided is a cast vane cluster with cooling holes drilled
into surfaces without a line of sight from the drilling equipment
to the hole location.
[0013] In accordance with an exemplary embodiment, a cast vane
cluster with enhanced cooling contains an inner and an outer
platform and at least two airfoils for directing a primary fluid
stream axially rearward. A duct is bounded by inner, an outer
endwall surfaces, and adjacent airfoil fluid directing surfaces.
The duct boundary contains at least one cooling hole for directing
a secondary fluid stream to enhance cooling and extend the life of
the cast vane cluster.
[0014] Other features and advantages will be apparent from the
following more detailed descriptions, taken in conjunction with the
accompanying drawings, which illustrate, by way of example, a
preferred embodiment cast vane cluster with enhanced cooling.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0015] FIG. 1 is a simplified schematic of a gas turbine engine
along a longitudinal axis.
[0016] FIG. 2 is an isometric view of a cast vane cluster of the
type used in the gas turbine engine of FIG. 1.
[0017] FIG. 3 is a sectional top view of a cast vane cluster of
FIG. 2 showing an obstructed surface area.
[0018] FIG. 4 is an isometric view of an embodiment of a hole
drilling guide for use in drilling holes into an obstructed surface
area of a cast vane cluster.
[0019] FIG. 5 is an isometric view of an alternate embodiment of a
hole drilling guide for use in drilling holes into an obstructed
surface area of a cast vane cluster.
[0020] FIG. 6 is a sectional top view of a cast vane cluster of
FIG. 2 showing a hole-drilling guide of FIG. 4 in place.
[0021] FIG. 7 is a sectional side view of a cast vane cluster of
FIG. 2 showing a hole-drilling guide of FIG. 4 in place.
[0022] FIG. 8 is a sectional side view of a vane cluster of FIG. 2
showing a hole-drilling guide of FIG. 5 in place.
[0023] FIG. 9 is a partial sectional view of a cooling hole of a
cast vane cluster of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[0024] A gas turbine engine 10 with a central, longitudinal axis 12
is shown in FIG. 1. The gas turbine engine contains a compressor
section 14, a combustor section 16 and a turbine section 18. A
primary fluid stream 20 is directed axially rearward from the
compressor section 14, through the combustor section 16 and into
the turbine section 18. Within the compressor section 14, a portion
of the primary fluid stream 20 is directed to one or more secondary
fluid streams 22, which bypass the combustor section 16, for use in
cooling components within the gas turbine engine 10. The turbine
section 18 typically comprises multiple, alternating stages of
rotating blades 24 and stationary vanes 26. Multiple vanes may be
cast as a single piece, which is typically called a cast vane
cluster 32 (shown in FIG. 2).
[0025] A cast vane cluster 32 comprises an inner platform 34, an
outer platform 36 and at least two airfoils 38 spanning radially
outward from the inner platform 34 to the outer platform 36. The
inner platform 34 has an inner endwall surface 40 facing the
airfoils and one or more inboard cavities 42 (shown in FIGS. 7 and
8) opposite the airfoils. The outer platform 36 has an outer
endwall surface 44 facing the airfoils and one or more outboard
cavities 46 opposite the airfoils. As shown in FIG. 3, each of the
airfoils 38 are comprised of a concave fluid directing surface 48,
a convex fluid directing surface 50, a forward facing leading edge
52 and a rearward facing trailing edge 54. Collectively, the
platform endwall surfaces 40, 44 and airfoil fluid directing
surfaces 48, 50 delineate a duct 56, as shown in FIG. 2, for
directing the primary fluid stream 20 rearward. One or more hollow
passages 58 extend through the interior of the airfoils 38,
connecting the inboard 42 and outboard cavities 46, (shown in FIG.
8). In surfaces that have a line of sight from a drilling equipment
direction 60, a multitude of cooling holes 62 may be drilled using
conventional laser or electrodischarge machining EDM drilling
methods.
[0026] A typical cooling hole 62, as shown in FIG. 9, is comprised
of an inlet cross sectional area 65, an outlet cross sectional area
66 and a bore 67. The bore 67 extends through an airfoil wall 94,
from the inlet cross sectional area 65 to the outlet cross
sectional area 66, along a central, longitudinal axis 68. Although
this example shows a cooling hole 62 with circular inlet and outlet
cross sectional areas 65, 66, it is to be understood that any shape
may be used. In addition, a cooling hole 62 may pass through an
inner platform 34 or an outer platform 36 as well as an airfoil
wall 94.
[0027] Each of FIGS. 6,7 and 8, shows an exemplary embodiment cast
vane cluster including one or more cooling holes 62 located in an
obstructed area 64 (shown in FIG. 3) of duct 56 (shown in FIG. 2).
Duct 56, extends axially across portions of the platform endwall
surfaces 40, 44, and radially across portions of the airfoil fluid
directing surfaces 48, 50. One or more cooling holes 62, located in
portions of the duct 56, may not be visible when viewed from an
external location. Additionally, one or more cooling holes 62, may
only have an outlet cross sectional area 66 visible when viewed
along a longitudinal axis 68 from an external location. An
exemplary cast vane cluster, with enhanced cooling as described
above, may be made using one or more of the hole-drilling guides
and methods described below.
[0028] FIG. 4 shows an embodiment of a hole-drilling guide 70 for
guiding a flexible, hole-drilling instrument 72 to a surface
without a line of sight from the hole drilling equipment to a
required hole location. The hole-drilling guide 70 comprises a body
74, one or more inlet apertures 76, one or more exit apertures 78
and a hollow, nonlinear raceway 80 connecting each corresponding
inlet 76 and exit 78 apertures. Shown in this example are three
raceways; however, any number may be used. An inlet aperture 76 may
contain a conical, bell-shaped or a similar shaped entrance 82 to
simplify insertion of the flexible, hole-drilling instrument 72.
The raceways 80 are a similar cross sectional shape as the
flexible, hole-drilling instrument 72 and are slightly larger in
sectional area. The clearance required between the flexible,
hole-drilling instrument 72 and the nonlinear raceway 80 depends on
the material of the hole-drilling guide 70 and the degree of
curvature of the nonlinear raceway 80. In this example, a radial
clearance of approximately 0.004 inch is used. Each of the exit
apertures 78 penetrates a substantially conforming face 84 of the
hole-drilling guide 70. The position of an exit aperture 78 in
relation to an obstructed surface of an article is controlled by
the substantially conforming faces 84, and by other locating
features such as rolls, pins, tabs, balls, bumps 86. A clamping lug
88 allows the hole-drilling guide 70 to be rigidly secured to the
article, once positioned.
[0029] FIG. 5 shows an alternate embodiment of a hole-drilling
guide 70. In the embodiment shown, the hole-drilling guide 70
comprises a body 74 and faces 84, which substantially conform to an
internal cavity or passage of an article. A clamping lug 88 allows
the hole-drilling guide 70 to be rigidly secured to the article,
once positioned, and contains one or more inlet apertures 76. One
or more exit apertures 78 penetrate the substantially corresponding
surfaces 84 and are connected to the inlet apertures 76 by one or
more nonlinear raceways 80. Shown in this example are three
nonlinear raceways; however, any number may be used.
[0030] In each of the above-described embodiments, the flexible,
hole-drilling instrument 72 is an EDM electrode. The EDM electrode
is formed of a flexible, electrically conductive wire with a
diameter of between approximately (0.009-0.016) inches. For
noncircular shaped holes, a flexible, electrically conductive foil
strip of a comparable dimension may be used. The body 74 of the
hole-drilling guide 70 is preferably made of an electrically
insulating material using solid freeform fabrication, casting,
molding, machining or any other suitable technique. Alternately,
the body 74 may be formed of an electrically conductive material
and the nonlinear raceways 80 may be coated with an electrically
insulating material.
[0031] In one aspect of a hole-drilling method, shown in FIG. 6, a
hole-drilling guide 70 is used to guide an EDM electrode 72 to a
portion of an obstructed surface area 64 (shown in FIG. 3) of a
cast vane cluster 32. In this example, the obstructed surface area
is located on an airfoil convex fluid directing surface 50. A cast
vane cluster 32 is loaded in a single or multiple axis EDM station
using a conventional tooling fixture 90. In this example, an AMCHEM
model HSD6-11, high-speed EDM station was used. A hole-drilling
guide 70 is placed into a duct 56 (shown in FIG. 2) of the cast
vane cluster 32 and accurately positioned in relation to the cast
vane cluster 32 by conforming surfaces 84 and a locating feature
86. The hole-drilling guide 70 is rigidly secured by a clamp 92
contacting a clamping lug 88. An EDM electrode 72 is inserted into
an inlet aperture 76 and advanced along a nonlinear raceway 80,
until the electrode contacts the airfoil convex fluid directing
surface 50. Once loaded into the raceway 80, the EDM electrode 72
is secured to the EDM station and plunged through an airfoil wall
94 into a hollow passage 58, forming a hole 62. Upon completion of
the hole 62, the EDM electrode 72 is retracted and the process is
repeated as required.
[0032] In another aspect of a hole-drilling method, shown in FIG.
7, a hole-drilling guide 70 is used to guide an EDM electrode 72 to
a portion of an obstructed surface area 64 (shown in FIG. 3) of a
cast vane cluster 32. In this example, the obstructed surface area
is located on an inner endwall surface 40. A cast vane cluster 32
is loaded in a single or multiple axis EDM station using a
conventional tooling fixture 90. In this example an AMCHEM model
HSD6-11, high-speed EDM station or equivalent may be used. A
hole-drilling guide 70 is placed into a duct 56 (shown in FIG. 2)
of the cast vane cluster 32 and accurately positioned in relation
to the cast vane cluster 32 by a conforming surface 84. The
hole-drilling guide 70 is rigidly secured by a clamp 92 contacting
a clamping lug 88. An EDM electrode 72 is inserted into an inlet
aperture 76 and advanced along a nonlinear raceway 80, until the
electrode contacts the inner endwall surface 40. Once loaded into
the raceway 80, the EDM electrode 72 is secured to the EDM station
and plunged through an inner platform 34 into an inner cavity 42 of
the vane cluster 32, forming a hole 62. Upon completion of the hole
62, the EDM electrode 72 is retracted and the process is repeated
as required.
[0033] In yet another aspect of a hole-drilling method, shown in
FIG. 8, a hole-drilling guide 70 guides an EDM electrode 72 to a
portion of an obstructed surface area 64 (shown in FIG. 3) of a
cast vane cluster 32. In this example, the obstructed surface area
is located on an airfoil concave fluid directing surface 48, and is
accessed via a hollow passage 58. A cast vane cluster 32 is loaded
in a single or multiple axis EDM station using a conventional
tooling fixture 90. In this example, an AMCHEM model HSD6-11,
high-speed EDM station or equivalent may be used. A hole-drilling
guide 70 is inserted into the hollow passage 58 of the vane cluster
32 and accurately positioned in relation to the hollow passage 58
by conforming surfaces 84 and locating features 86. The
hole-drilling guide 70 is rigidly secured by a clamp 92 contacting
a clamping lug 88. An EDM electrode 72 is inserted into an inlet
aperture 76 and advanced along a nonlinear raceway 80, until the
electrode contacts the surface of the hollow passage 58. Once
loaded into the raceway 80, the EDM electrode 72 is secured to the
EDM station and plunged through the airfoil wall 94, forming a hole
62 (not shown. Upon completion of the hole 62, the EDM electrode 72
is retracted and the process is repeated as required.
[0034] The foregoing has described a cast vane cluster with
enhanced cooling and its method of manufacture. It will be apparent
to those skilled in the art that various modifications thereto can
be made without departing from the spirit and scope of the
invention as described in the appended claims.
* * * * *