U.S. patent application number 12/216078 was filed with the patent office on 2009-12-31 for aft frame with oval-shaped cooling slots and related method.
This patent application is currently assigned to General Electric Company. Invention is credited to Vijay Kumar Turaga.
Application Number | 20090324387 12/216078 |
Document ID | / |
Family ID | 41360901 |
Filed Date | 2009-12-31 |
United States Patent
Application |
20090324387 |
Kind Code |
A1 |
Turaga; Vijay Kumar |
December 31, 2009 |
Aft frame with oval-shaped cooling slots and related method
Abstract
An aft frame adapted to interface between a combustor transition
piece and a first stage turbine nozzle includes: a closed-periphery
frame comprised of a top, bottom and pair of side walls. A
plurality of cooling holes or apertures having elliptical or oval
cross-sectional shapes are provided in one or more of the top,
bottom and pair of side walls, extending axially through the
closed-periphery frame. The cooling holes have major and minor axes
arranged such that the major axes are substantially parallel with
the top and bottom walls.
Inventors: |
Turaga; Vijay Kumar;
(Hyderabad Andhra Pradesh, IN) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
41360901 |
Appl. No.: |
12/216078 |
Filed: |
June 30, 2008 |
Current U.S.
Class: |
415/115 ;
415/182.1 |
Current CPC
Class: |
F01D 9/023 20130101;
F01D 25/14 20130101 |
Class at
Publication: |
415/115 ;
415/182.1 |
International
Class: |
F01D 5/08 20060101
F01D005/08 |
Claims
1. An aft frame adapted to interface between a combustor transition
piece and a first stage turbine nozzle comprising: a
closed-periphery frame comprised of a top, bottom and pair of side
walls; and a plurality of cooling apertures extending through one
or more of said top, bottom and pair of side walls, said plurality
of cooling apertures having an elliptical or oval cross-sectional
shape.
2. The aft frame of claim 1 wherein one or more of said plurality
of cooling apertures are provided in each of said top, bottom and
pair of side walls.
3. The aft frame of claim 1 wherein said plurality of cooling
apertures extend in an axial direction through said
closed-periphery frame.
4. The aft frame of claim 2 wherein said plurality of cooling
apertures extend in an axial direction through said
closed-periphery frame.
5. The aft frame of claim 1 wherein said plurality of cooling
apertures have major and minor axes, arranged with said major axes
substantially parallel with said top and bottom walls.
6. The aft frame of claim 4 wherein said plurality of cooling
apertures have major and minor axes, arranged with said major axes
substantially parallel with said top and bottom walls.
7. An aft frame adapted to interface between a combustor transition
piece and a first stage turbine nozzle comprising: a
closed-periphery frame comprised of a top, bottom and pair of side
walls; and a plurality of cooling apertures having elliptical or
oval cross-sectional shapes provided in each of said top, bottom
and pair of side walls, extending axially through said
closed-periphery frame; and wherein said plurality of cooling
apertures have major and minor axes, arranged such that said major
axes are substantially parallel with said top and bottom walls.
8. A method of forming a turbine aft frame adapted to interface
between a combustor transition piece and a first stage turbine
nozzle comprising: a) providing a closed periphery aft frame having
top and bottom walls and a pair of side walls, and b) forming
elliptically-shaped cooling holes in at least one of said top,
bottom and pair of side walls, extending axially through the aft
frame.
9. The method of claim 8 including providing said
elliptically-shaped cooling holes in all of said top, bottom and
pair of side walls.
10. The method of claim 8 wherein said elliptically-shaped cooling
holes have major and minor axes, and wherein step b) includes
arranging said elliptically-shaped cooling holes with said major
axes substantially parallel to said top and bottom walls.
Description
[0001] This invention relates to turbine cooling technology and,
more specifically, to the cooling of an aft frame component
interfacing between the combustor transition piece and a stage 1
turbine nozzle.
BACKGROUND OF THE INVENTION
[0002] A "transition piece" as understood in the context of a
can-annular combustor for a power generating gas turbine, is a duct
that connects the combustor liner with the first stage nozzle of
the turbine. The aft frame is a component which is located at the
exit end of the transition piece and thus acts as an interface
between the transition piece and the stage 1 nozzle. It is exposed
to hot gases flowing into the stage 1 nozzle and therefore, cooling
of the aft frame component is of concern.
[0003] More specifically, hot gases flowing through the transition
piece recirculate in a groove between the aft frame and the stage 1
nozzle, causing high thermal gradients. Accordingly, effective
cooling needs to be provided on the trailing face of the aft frame,
i.e., that side of the frame facing the stage 1 nozzle. Currently,
typical aft frame configurations incorporate cooling holes with
circular cross sections in order to divert a portion of flow
through an impingement sleeve (which surrounds the transition
piece) into these holes to cool the aft frame.
[0004] There remains a need, however, for more effective cooling of
the aft frame of the transition piece.
BRIEF DESCRIPTION OF THE INVENTION
[0005] In accordance with an exemplary but non-limiting embodiment
of this invention, oval or elliptical-shaped cooling holes are
provided about the periphery of the aft frame. Because oval or
elliptical-shaped holes provide more surface area for effective
convection cooling for a given cross-sectional area, cooling of the
aft frame is improved.
[0006] Accordingly, in one aspect, the invention relates to an aft
frame adapted to interface between a combustor transition piece and
a first stage turbine nozzle comprising: a closed-periphery frame
comprised of a top, bottom and pair of side walls; and a plurality
of cooling apertures extending through one or more of the top,
bottom and pair of side walls, the cooling apertures having an
elliptical or oval cross-sectional shape.
[0007] In another aspect, the invention relates to an aft frame
adapted to interface between a combustor transition piece and a
first stage turbine nozzle comprising: a closed-periphery frame
comprised of a top, bottom and pair of side walls; and a plurality
of cooling apertures having an elliptical or oval cross-sectional
shape provided in each of the top, bottom and pair of side walls,
extending axially through the frame; and wherein the cooling
apertures have major and minor axes, arranged such that the major
axes are substantially parallel with the top and bottom walls.
[0008] In still another aspect, the invention relates to a method
of forming a turbine aft frame adapted to interface between a
combustor transition piece and a first stage turbine nozzle
comprising: a) providing a closed periphery aft frame having top
and bottom and a pair of side walls; and b) forming
elliptical-shaped cooling holes in at least one of said top, bottom
and pair of side walls, extending axially through the aft
frame.
[0009] The invention will now be described in more detail in
connection with the figures identified below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a perspective view of a typical transition piece
aft frame of known construction;
[0011] FIG. 2 is an enlarged detail showing known circular cooling
holes or slots formed in the aft frame; and
[0012] FIG. 3 is an enlarged detail illustrating the oval or
elliptical shape of the cooling holes to be employed in an aft
frame of, for example, the type shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0013] With reference to FIG. 1, an aft frame 10 that serves as an
interface between a conventional transition piece (not shown) and a
first stage turbine nozzle (also not shown) includes top and bottom
walls 12, 14, respectively and a pair of side walls 16, 18 that
complete the closed-periphery frame. Mounting hardware, such as
brackets 20 and 22, facilitate connection of the aft frame to the
first stage turbine nozzle. The exact manner of attachment is not
part of this invention, however, and in any event, any suitable
attachment technique may be employed. It will be appreciated that a
conventional transition piece is attached to the opposite side of
the aft frame, extending between the first stage nozzle and the
combustor liner. Examples of this type of arrangement may be found
in U.S. Pat. Nos. 6,412,268 and 6,547,257.
[0014] With reference now to FIG. 2, circular cooling holes 24 are
typically spaced about the periphery of the aft frame, allowing
cooling air to flow axially into the holes and through the aft
frame, thereby cooling the frame.
[0015] FIG. 3 illustrates a modified cooling hole shape that
provides better and more efficient cooling of the aft frame.
Specifically, some or all of the axially extending cooling holes or
apertures 26 have an elliptical or oval cross-sectional shape, thus
increasing the surface area for more effective convection cooling
for a given cross-sectional area. Elliptical cooling holes or
apertures 26 may be used exclusively or in combination with
circular cooling holes (e.g., holes 24) as determined by specific
cooling requirements. Dimensions for the elliptical holes may also
vary in accordance with cooling requirements. The elliptical
cooling holes 26 may be provided in any one or more (or all) of the
top, bottom and side walls 12, 14, 16 and 18, respectively, of the
aft frame. Preferably, the major axes of the cooling apertures are
substantially parallel to the top and bottom walls of the aft
frame.
[0016] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiment, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
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