U.S. patent application number 11/529113 was filed with the patent office on 2010-12-09 for impingement cooling of a turbine airfoil with large platform to airfoil fillet radius.
This patent application is currently assigned to United Technologies Corporation. Invention is credited to Joseph W. Bridges, JR., Matthew A. Devore, Corneil S. Paauwe.
Application Number | 20100310367 11/529113 |
Document ID | / |
Family ID | 38657961 |
Filed Date | 2010-12-09 |
United States Patent
Application |
20100310367 |
Kind Code |
A1 |
Devore; Matthew A. ; et
al. |
December 9, 2010 |
Impingement cooling of a turbine airfoil with large platform to
airfoil fillet radius
Abstract
A method of impingement cooling a turbine airfoil with a large
platform to airfoil fillet radius which includes coring the airfoil
fillet such that the fillet wall is maintained at a minimum
thickness. An impingement tube is used which follows the fillet
contour as it transitions from airfoil to platform and supplies
impingement air to the airfoil walls. The air subsequently flows
across the airfoil internal wall and finally exits the airfoil
through airfoil holes to provide film cooling to the airfoil
fillet.
Inventors: |
Devore; Matthew A.;
(Manchester, CT) ; Bridges, JR.; Joseph W.;
(Durham, CT) ; Paauwe; Corneil S.; (Manchester,
CT) |
Correspondence
Address: |
MARJAMA MULDOON BLASIAK & SULLIVAN LLP
250 SOUTH CLINTON STREET, SUITE 300
SYRACUSE
NY
13202
US
|
Assignee: |
United Technologies
Corporation
|
Family ID: |
38657961 |
Appl. No.: |
11/529113 |
Filed: |
September 28, 2006 |
Current U.S.
Class: |
416/1 ;
416/97R |
Current CPC
Class: |
Y02T 50/60 20130101;
F01D 5/189 20130101; F05D 2260/202 20130101; F05D 2260/201
20130101; F05D 2240/81 20130101; Y02T 50/676 20130101; F01D 9/041
20130101 |
Class at
Publication: |
416/1 ;
416/97.R |
International
Class: |
F01D 5/18 20060101
F01D005/18 |
Goverment Interests
STATEMENT OF GOVERNMENT INTEREST
[0001] The United States Government has certain rights in this
invention pursuant to Contract No. N00019-02-N-3003 between the
United States Navy and United Technologies Corporation.
Claims
1. A method of impingement cooling a turbine airfoil with a large
platform to airfoil fillet radius which contains a plurality of
cooling holes through the airfoil wall which comprises: (a) coring
the airfoil fillet such that the fillet wall is maintained at a
minimum thickness; (b) inserting into the airfoil an impingement
tube which follows the fillet contour to platform transition; (c)
applying impingent air through the impingement tube to the airfoil
walls and (d) using the impinged air to subsequently flow through
airfoil and fillet holes to provide film cooling to the airfoil
fillet.
2. The method of claim 1 in which the fillet has been cored such
that the backwall of the fillet substantially follows the exterior
contour of the fillet surface.
3. A system for impingement cooling a turbine airfoil with a large
platform to airfoil fillet radius which contains a plurality of
cooling holes through the airfoil wall which comprises: (a) an
airfoil having an airfoil fillet which exhibits a fillet wall
thickness similar to the wall thickness of the airfoil wall; and
(b) said airfoil having an impingement tube inserted internally
therein said tube being configured to follow the fillet contour to
platform transition and having holes for delivery of impingement
air to said airfoil fillet.
4. (canceled)
5. A method of impingement cooling a turbine airfoil with a large
platform to airfoil fillet radius which comprises: (a) providing an
airfoil having an airfoil fillet having a defined contour and a
minimum fillet wall thickness with said airfoil having a plurality
of cooling holes through the airfoil wall; (b) inserting into said
airfoil an impingement tube positioned to follow the fillet
contour; (c) applying impingent air through said tube to the
airfoil and fillet walls; (d) with said impinged air thereby
providing film cooling to the airfoil fillet.
6. A turbine airfoil which includes: (a) an airfoil fillet having a
fillet wall maintained at a thickness similar to that of the
airfoil side walls, with said airfoil containing a plurality of
cooling holes through the airfoil wall; (b) an impingement tube
inserted into said airfoil and positioned adjacent said fillet
which follows the fillet contour; (c) whereby impingent air is
passed through said tube to the airfoil and fillet walls to provide
film cooling to the airfoil fillet.
7. The airfoil of claim 6 in which the airfoil fillet backwall is
contoured to follow the contour of the exterior fillet surface.
Description
FIELD OF THE INVENTION
[0002] This invention relates generally to airfoils, and more
specifically to the impingement cooling of a large platform to
airfoil fillet radius on a turbine airfoil.
BACKGROUND OF THE INVENTION
[0003] In a conventional turbine airfoil, cooling air is supplied
to the airfoil through an impingement tube which has been inserted
into and is located adjacent the internal wall of a hollow or cored
airfoil. The air travels through the impingement tube and exits
through small holes toward the airfoil wall. The air exiting the
impingement tube is at a high velocity and provides impingement
cooling on the airfoil wall. The air then flows along the wall of
the airfoil until it exits through cooling holes in the airfoil
surface, where the air finally functions to film cool the airfoil.
The fillet between the airfoil and platform external surfaces is
typically uncooled due to its small radius size (typically
0.045-0.150).
[0004] As the size of the airfoil fillet increases from 0.150 to
upwards of an inch or greater, it becomes difficult to continue to
ignore cooling of the filleted region of the airfoil. The large
fillet increases the area and volume of material exposed to high
temperatures such that it becomes necessary to provide a method of
cooling to prevent part durability shortfalls such as oxidation and
or thermal mechanical fatigue. It can therefore been seen that
there is a need for an effective method of cooling large filleted
airfoils which is not currently available to the field.
SUMMARY OF THE INVENTION
[0005] It is therefore an object of the present invention to
provide a system for impingement cooling of a turbine airfoil with
a large platform to airfoil fillet which overcomes the problems of
the prior art described above.
[0006] It is another object of the present invention to provide for
a method of producing an airfoil fillet with wall thicknesses
similar to that of the adjacent airfoil wall.
[0007] It is a further object of the present invention to provide
an impingement tube which follows the contour of both the airfoil
and airfoil fillet.
[0008] It is yet another object of the invention to provide a
combination of a thin walled airfoil fillet and impingement tube
design which provides for optimum impingement cooling of an airfoil
with a large platform to airfoil fillet radius.
[0009] The invention is directed to impingement cooling of turbine
airfoils with large fillets by initially within the casting process
allowing the ceramic airfoil core to follow the exterior shape of
the airfoil as it transitions from the airfoil to fillet to
platform. After casting of the airfoil and removing the ceramic
core to produce hollow features within the airfoil, the described
process provides the airfoil and fillet with similar wall
thicknesses. This concept allows the fillet wall thickness to be
maintained to a minimum to allow for effective cooling. A thin
sheet metal impingement tube is then positioned within the hollow
airfoil and is configured to follow the airfoil to fillet to
platform contour at a prescribed distance from the internal wall
(typically 0.02-0.100). Utilizing the thin walled fillet and
impingement tube as described, it is then possible to effectively
cool the fillet area. In operation, cooling air enters the turbine
airfoil through the impingement tube and impinges against the
internal airfoil and fillet wall as it exits through multiple holes
in the impingement tube. The air then travels across the internal
surface of the fillet until it turns and exits the airfoil or
fillet through multiple cooling holes. The cooling air after
exiting the airfoil functions to film cool the surface of the
airfoil or fillet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] For a better understanding of these and other objects of the
invention, reference will be made to the following detailed
description of the invention, which is to be read in association
with the following drawings, wherein:
[0011] FIG. 1 is a side elevation in section illustrating the
component parts of a jet engine;
[0012] FIG. 2 is an enlarged partial view showing a turbine vane
located in the first stage of the turbine section of the
engine;
[0013] FIG. 3 is a partial side sectional view of a conventional
airfoil with a typical fillet and associated impingement tube.
[0014] FIG. 4 is a partial side sectional view of a conventional
airfoil with a large fillet.
[0015] FIG. 5 is a sectional view of a conventional airfoil with a
ceramic core.
[0016] FIG. 6 is a sectional view of a cored airfoil of the present
invention.
[0017] FIG. 7 is a partial section view of the airfoil of FIG. 6
with an impingement tube in place.
DETAILED DESCRIPTION OF THE INVENTION
[0018] The incorporation of large fillets into turbine airfoils
requires a special method of cooling the filleted region of the
airfoil. The present invention provides impingement cooling to the
airfoil fillet using a uniquely designed airfoil cooling tube. In
the present invention the airfoil fillet is hollowed out by coring
the airfoil fillet region in the casting process such that the
fillet wall does not become too thick to cool. The present
invention then incorporates an impingement tube designed to follow
the airfoil to fillet to platform transition at a prescribed
distance, and apply impingent air through holes in the impingement
tube to the internal airfoil and fillet wall. The impinged air
subsequently flows through airfoil and fillet holes to the airfoil
external surface and provides film cooling to the airfoil
fillet.
[0019] Referring initially to FIG. 1, there is shown the main
components of a jet engine, generally referenced 10 in schematic
outline. The engine includes a diffuser section 12 having a conical
inlet 13 in which RAM air is initially compressed and then passed
on to an axial compressor 14 by means of a fan 16 located at the
entrance to the compressor. Compressed air from the last stage of
the compressor is fed into a series of combustion chambers, one or
which is depicted as 17, where the compressed air is mixed with
fuel and is ignited. Gases from the combustors are passed on to the
turbine section of the engine 18 where the hot gases are expanded.
The turbine section of the engine is coupled directly to the
compressor by a common shaft 19. The power developed in the turbine
18 is thus utilized to drive the compressor and other auxiliary
engine components. Gases leaving the turbine 18 are further
expanded in the exhaust nozzle 20 of the engine and are ejected at
a velocity greater than the flight velocity to produce thrust. FIG.
2 is an enlarged view of an airfoil 23 located in the first stage
of the turbine 18, which is exposed to gases from the combustion
chamber that are at relatively high temperatures and pressures.
Accordingly, airfoil cooling which is supplied to the airfoil from
areas 24 and 25 is at a premium. FIG. 3 is a section taken through
airfoil 23 further illustrating the internal construction of the
airfoil.
[0020] FIG. 3 shows a section of a hollow airfoil 30, having an
airfoil wall 32, small fillet 36 and platform 38. The airfoil wall
32 consists of an external wall surface 31 and an internal wall
surface 33 as well as a plurality of cooling holes 34. A thin sheet
metal impingement tube 40 is positioned adjacent internal wall 33
at a typical distance of 0.020 to 0.100. The impingement tube 40
also contains a plurality of cooling holes 41. In this arrangement
cooling air is supplied to the hollow airfoil through the
impingement tube. Air exits the impingement tube by impinging onto
the internal airfoil surface 33 through holes 41 in the impingement
tube. The air then flows along the internal wall of the airfoil
until its exits through cooling holes 34 in the airfoil surface,
where it is finally used to film cool the external airfoil surface
31. The fillet 36 remains uncooled in this typical airfoil
section
[0021] As the size of the airfoil fillet increases, it becomes
difficult to ignore cooling this region of the airfoil and airfoil
fillet. Eventually the external fillet area exposed to hot gas
temperatures and the increased material contained within the fillet
require that it be cooled in order to maintain part life.
[0022] In FIG. 4, airfoil 50 shows the effect on fillet area of
increasing the fillet radius by conventional means. In order to
cool a big fillet it first becomes necessary to hollow out the
fillet at the casting stage. In airfoil manufacture the internal
cavities of the airfoil are produced using ceramic cores. In the
typical airfoil shown in FIG. 5, the airfoil ceramic core 48
extends radially outward of the airfoil 30.
[0023] In order to allow proper cooling of a fillet similar to that
of FIG. 4 it is necessary first to hollow the fillet region of the
airfoil. It has been found that this can be accomplished by
allowing the ceramic core 70 (FIG. 6) to follow the exterior shape
of the airfoil as it transitions from airfoil 60 to fillet 64 to
platform 66. This arrangement is shown in FIG. 6. Note that the
airfoil wall 62 increases in thickness as the fillet transitions
from the airfoil to the platform. This is done in order to allow
the core to shift radially with casting process variation without
creating a minimum wall condition in the platform or fillet.
[0024] With the airfoil and fillet hollowed, it now becomes
necessary to insert an impingement tube 72 (FIG. 7) into the
airfoil which follows the airfoil to fillet 62 to platform 66
contour. FIG. 7 shows the big fillet airfoil 60 with an impingement
tube 72 in place.
[0025] With a hollow airfoil fillet with impingement tube inserted
it now becomes possible to adequately cool big fillets. Cooling air
will enter into the impingement tube 72 and impinge onto the
internal airfoil and fillet wall surface 74 as it exits through
holes 73 in the impingement tube 72. The air will then travel
across the surface of the airfoil and fillet until it turns and
exits the airfoil fillet through cooling holes 68 which acts to
film cool the external surface of the fillet.
[0026] While the present invention has been particularly shown and
described with reference to the preferred mode as illustrated in
the drawing, it will be understood by one skilled in the art that
various changes in detail may be effected therein without departing
from the spirit and scope of the invention as defined by the
claims.
* * * * *