U.S. patent application number 13/174166 was filed with the patent office on 2013-01-03 for system and method for adaptive impingement cooling.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. Invention is credited to James A. Dierberger.
Application Number | 20130000309 13/174166 |
Document ID | / |
Family ID | 46456392 |
Filed Date | 2013-01-03 |
United States Patent
Application |
20130000309 |
Kind Code |
A1 |
Dierberger; James A. |
January 3, 2013 |
SYSTEM AND METHOD FOR ADAPTIVE IMPINGEMENT COOLING
Abstract
An adaptive cooling structure comprises a mounting support, a
liner, and a spacer. The mounting support has a coolant aperture
for directing cooling air through the support. The liner has a
first surface facing away from the mounting support and a second
surface facing towards the support. The liner is coupled to the
mounting support, and the spacer is positioned between the support
and the liner. The positioning of the spacer creates a chamber
between the mounting support and the liner, thus allowing the
cooling air to impinge on the second surface of the liner. The
liner wall is configured to deflect away from the mounting support
to expand the chamber, thus allowing the cooling air to further
impinge on the second surface of the liner.
Inventors: |
Dierberger; James A.;
(Hebron, CT) |
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Hartford
CT
|
Family ID: |
46456392 |
Appl. No.: |
13/174166 |
Filed: |
June 30, 2011 |
Current U.S.
Class: |
60/752 ;
165/67 |
Current CPC
Class: |
F23R 3/04 20130101; F23R
3/007 20130101; F23R 3/002 20130101; F23R 2900/03044 20130101; F23R
2900/03042 20130101 |
Class at
Publication: |
60/752 ;
165/67 |
International
Class: |
F23R 3/42 20060101
F23R003/42; F28F 9/007 20060101 F28F009/007 |
Claims
1. A structure for adaptive cooling comprising: a mounting support
having a coolant aperture for directing cooling air through the
mounting support; a liner coupled to the mounting support,
including a wall having a first surface facing away from the
mounting support and a second surface facing toward the mounting
support; a spacer positioned between the mounting support and the
liner, the spacer creating a chamber between the mounting support
and the liner, thus allowing the cooling air to impinge on the
second surface of the liner; and wherein the liner wall is
configured to deflect away when exposed to hot air from the
mounting support to expand the chamber, thus allowing the cooling
air to further impinge on the second surface of the liner.
2. The structure of claim 1, wherein the spacer positions the liner
a distance away from the mounting support to provide impingement
cooling at a first rate, and wherein the liner is configured to
deflect an amount to increase the distance such that impingement
cooling is provided at a second, greater rate.
3. The structure of claim 1, wherein the liner permits the cooling
air to pass through and exit the first surface, forming a film.
4. The structure of claim 1, wherein the coolant aperture has a
diameter D, the chamber has a distance L between the liner and the
support that is less than three times the value of D, and the liner
wall deflects away from the mounting support when exposed to hot
air, increasing L to approximately three times the value of D.
5. The structure of claim 1, wherein a mounting post with a
threaded stud extends from the second surface of the liner wall and
through the support, the mounting post is surrounded by a washer
acting as the spacer between the support and the liner, and a nut
secures the mounting post to the support.
6. The structure of claim 1, wherein the first surface is a hot
surface with a hot spot location, and the hot spot location causes
the liner wall to deflect away from the mounting support.
7. The structure of claim 1, wherein the liner is an impingement
film cooled panel acting as a heat shield in a gas turbine
combustor.
8. The structure of claim 1, wherein the liner is an impingement
film cooled liner in a gas turbine augmenter.
9. A method of adaptively cooling a liner coupled to a support with
a spacer positioned between the liner and the support, the method
comprising: introducing cooling air into a coolant aperture in the
support; directing the cooling air into a chamber between the
support and the liner and impinging the cooling air against the
liner at a first rate; deflecting the liner away from the mounting
support, expanding the chamber; and directing the cooling air into
the chamber and further impinging the cooling air against the liner
at a second rate.
10. The method of claim 9, wherein the spacer positions the liner a
distance away from the mounting support to provide impingement
cooling at the first rate, and wherein the liner is configured to
deflect an amount to increase the distance such that impingement
cooling is provided at the second rate.
11. The method of claim 10, wherein the second rate is greater than
the first rate.
12. The method of claim 9, wherein the coolant aperture has a
diameter D, the chamber has a distance L between the liner and
support that is less than three times the value of D, and the
deflecting step causes the liner to deflect away from the mounting
support, increasing L to between approximately one to four times
the value of D.
13. The method of claim 10, wherein the deflecting step causes the
liner to deflect away from the mounting support, increasing L to
between approximately two to four times the value of D.
14. The method of claim 10, wherein the deflecting step causes the
liner to deflect away from the mounting support, increasing L to
approximately three times the value of D.
15. The method of claim 10, wherein the chamber has a distance L
between the liner and support that is between approximately two to
three times the value of D, and the deflecting step causes the
liner to deflect away from the mounting support, increasing L to
between approximately two to four times the value of D.
16. The method of claim 13, wherein the deflecting step causes the
liner to deflect away from the mounting support, increasing L to
between approximately 2.5 to 3.5 times the value of D.
17. The method of claim 13, wherein the deflecting step causes the
liner to deflect away from the mounting support, increasing L to
approximately three times the value of D.
18. The method of claim 9, and further comprising: directing the
cooling air to pass through the liner and exit the first surface,
forming a film.
19. The method of claim 9, wherein a hot spot location on the liner
causes the deflecting step.
20. The method of claim 9, wherein the liner is an impingement film
cooled panel acting as a heat shield in a gas turbine combustor and
the liner is exposed directly to hot air.
21. The method of claim 9, wherein the liner is an impingement film
cooled liner in a gas turbine augmenter and the liner is exposed
directly to hot air.
Description
BACKGROUND
[0001] The present invention relates to cooling systems, and in
particular, to a system and method for adaptive impingement cooling
for use in hot environments such as those found in gas turbine
engines.
[0002] Gas turbine engines operate according to a continuous
Brayton cycle where a pressurized air and fuel mixture is ignited
in a combustor to produce a flowing stream of hot gas. The air is
compressed, used for combustion, expands through a turbine, and
finally exits the engine. Some gas turbine engines also include an
augmentation system downstream of the turbine, where fuel is also
introduced and ignited to increase thrust. Most often, the
temperature of the primary air is higher than the melting
temperatures of the materials that form the combustor, turbine, and
augmentation system components. As a result, adequate cooling is
integral to the function of gas turbine engines.
[0003] It is common to combine the benefits of both impingement
cooling and film cooling in gas turbine engines. This combination
of impingement and film cooling is particularly useful in parts
such as combustors and augmentation systems where local hot spots
develop. Current practice is to design impingement cooling
structures neglecting the deformation that occurs in local hot
spots as the temperature in the hot spots increases. As a result,
impingement cooling effectiveness decreases as the deformation
develops, causing hot spots to become even hotter. Cooling
effectiveness should be the highest at local hot spots.
SUMMARY
[0004] An adaptive cooling structure comprises a mounting support,
a liner, and a spacer. The mounting support has a coolant aperture
for directing cooling air through the support. The liner has a
first surface facing away from the mounting support and a second
surface facing towards the support. The liner is coupled to the
mounting support, and the spacer is positioned between the support
and the liner. The positioning of the spacer creates a chamber
between the mounting support and the liner, thus allowing the
cooling air to impinge on the second surface of the liner. The
liner wall is configured to deflect away from the mounting support
to expand the chamber, thus allowing the cooling air to further
impinge on the second surface of the liner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a simplified cross-sectional view of an embodiment
of a gas turbine engine which employs the adaptive impingement
cooling system and method of the present invention.
[0006] FIG. 2 is a partial isometric view of an embodiment of the
adaptive cooling structure of the present invention.
[0007] FIG. 3 is a cross-sectional view of the embodiment of the
adaptive cooling structure in FIG. 2 at a non-hot spot
location.
[0008] FIG. 4 is a cross-sectional view of the embodiment of the
adaptive cooling structure in FIG. 2 at a hot spot location.
[0009] FIG. 5 is a graph showing preferred ranges of impingement
effectiveness for designing the adaptive cooling structure of the
present invention.
DETAILED DESCRIPTION
[0010] FIG. 1 is a simplified cross-sectional view of mixed flow
turbofan engine 10 which can employ the adaptive impingement
cooling system and method of the present invention. Turbofan engine
10 includes augmentation system 12, fan duct 14, drive fan 16, low
pressure compressor 18, high pressure compressor 20, combustor 22,
high pressure turbine 24, low pressure turbine 26, and exhaust
nozzle 28. Drive fan 16 and low pressure compressor 18 are driven
by low pressure turbine 26 with shaft 30. High pressure compressor
20 is driven by high pressure turbine 24 with shaft 32. High
pressure compressor 20, combustor 22, high pressure turbine 24 and
shaft 32 comprise the core of turbofan engine 10. Augmentation
system 12 includes augmenter duct 34 and augmenter liner 36.
[0011] Ambient air A.sub.Ambient enters turbofan engine 10 at inlet
38 through drive fan 16. Drive fan 16 is rotated by low pressure
turbine 26 to accelerate A.sub.Ambient thereby producing a major
portion of the thrust output of turbofan engine 10. Accelerated
A.sub.Ambient is divided into two streams of air: primary air
A.sub.P and secondary air A.sub.S. Secondary air A.sub.S, also
known as bypass air, passes into fan duct 14 where it passes on to
augmentation system 12. Primary air A.sub.P, also known as hot air,
is a stream of air that is directed first into low pressure
compressor 18 and then into high pressure compressor 20.
Pressurized primary air A.sub.P is then passed into combustor 22
where it is mixed with a fuel supply and ignited to produce the
high energy gases used to turn high pressure turbine 24 and low
pressure turbine 26. Combusted primary air A.sub.P and secondary
air A.sub.S are passed through augmentor duct 34 and into
augmentation system 12 where a secondary combustion process can be
carried out. Augmentation liner 36 prevents heat damage to
augmentation system 12 and turbofan engine 10. Exhausted air
A.sub.Ex exits turbofan engine 10 through exhaust nozzle 28. The
adaptive cooling structure of the present invention can be used in
combustor 22 or augmentation system 12.
[0012] Referring now to FIG. 2, adaptive cooling structure 40, such
as augmentation liner 36 in augmentation system 12 or a heat shield
in combustor 22 (FIG. 1), is exposed directly to hot air A.sub.p.
Adaptive cooling structure 40 includes liner 42 and mounting
support 44. Liner 42 is affixed to mounting support 44 by fastening
means 46 such as threaded studs, bolts, rivets, welds, or other
suitable fastening means. Liner 42 includes liner wall 48 with one
or more film apertures 50. Liner wall 48 has first surface 52
facing away from the mounting support 44 and second surface 54
facing towards mounting support 44. Liner wall 48 may be made from
a high temperature, cast, forged or sheet material such as nickel
or cobalt for example. First surface 52 may also include one or
more layers of thermal barrier coating (TBC) 56, such as a metallic
or ceramic material, for improved insulation from hot air A.sub.p.
Thermal gradient lines 58 depict the temperature differential
across first surface 52 and indicate that hot spot location 60 is
present in the area of liner 42. Spallation of TBC layer 56 is also
indicative of the presence of hot spot location 60. Mounting
support 44 includes one or more coolant apertures 62.
[0013] Coolant apertures 62 in mounting support 44 direct cooling
air A.sub.C, such as pressurized air bled from compressor 18 or 20
(FIG. 1), to second surface 54 of liner 42. Coolant apertures 62
are perpendicular to the flow of hot air A.sub.p. In an alternative
embodiment, coolant apertures 62 can be angled to the flow. Cooling
air A.sub.C provides cooling to reduce the operating temperature of
mounting support 44 as it flows through coolant apertures 62.
Cooling air A.sub.C exits coolant apertures 62, flows between
mounting support 44 and liner wall 48, impinging on second surface
54. Cooling air A.sub.C exits liner 42 through film apertures 50 in
liner wall 48, and provides film cooling of first surface 52. In an
alternative embodiment, liner 42 is porous instead of having film
apertures 50, and cooling air A.sub.C exits liner 42 through the
pores.
[0014] The present invention combines the benefits of both
impingement cooling and film cooling and is particularly useful in
parts such as combustor 22 and augmentation system 12 (FIG. 1)
where local hot spots develop. When liner wall 48 of adaptive
cooling structure 40 is exposed to hot air A.sub.p, hot spot
location 60 causes liner wall 48 to deflect away from mounting
support 44 (as seen in FIG. 4). Impingement cooling has parameters
which when engineered can provide an increased impingement rate
upon deflection of liner wall 48. Thus, the present invention
configures these parameters to accommodate such deflections as
ignoring these parameters results in a less efficient cooling
structure.
[0015] FIG. 3 is a cross-sectional view of adaptive cooling
structure 40 taken at a non-hot spot location along line 3-3 of
FIG. 2. Liner 42 of adaptive cooling structure 40 includes mounting
post 64. Mounting post 64 with fastening means 46 is surrounded by
spacer 66 and extends from second surface 54 of liner wall 48
through mounting support 44. Nut 68 secures mounting post 64 to
mounting support 44 via fastening means (threads) 46. Spacer 66,
such as a washer or other suitable spacer, creates chamber 70
between mounting support 44 and liner 42 for impingement cooling.
Chamber 70 has distance L between mounting support 44 and liner 42.
Coolant apertures 62 have a circular cross section with diameter D.
In other embodiments, coolant apertures 62 can have a non-circular
cross section with effective diameter D.
[0016] Adaptive cooling structure 40 is directly exposed to hot air
Ap. Cooling air A.sub.C flows through coolant apertures 62 and
enters chamber 70, impinging on second surface 54. Cooling air
A.sub.C exits first surface 52 through film apertures 50 in liner
wall 48, forming a film. Film apertures 50 have a circular cross
section, but can have a non-circular cross section or can be
flared. Film apertures 50 are angled with the flow of hot air
A.sub.P. In alternative embodiments, film apertures 50 can be at
another angle or can be perpendicular to the flow. The location of
coolant apertures 62 is staggered in relation to film apertures 50.
In alternative embodiments, the location of coolant apertures 62
can be aligned with film apertures 50 or completely independent of
the location of film apertures 50.
[0017] In impingement cooling a ratio L/D of distance L to diameter
D of approximately three provides a preferred impingement heat
transfer coefficient. When hot spot location 60 causes liner wall
48 to deflect away from mounting support 44 (as seen in FIG. 4),
distance L increases and ratio L/D increases as a result. Thus, the
present invention is designed to accommodate the deformation by
configuring adaptive cooling structure 40 with a ratio L/D lower
than three. For adaptive cooling structure 40, employing both
impingement cooling and film cooling, the preferred as-fabricated
ratio L/D is in the range between approximately two and three, and
more specifically 2.5. The configuration of the present invention
thus results in increased impingement cooling effectiveness upon
deformation in the hot spot, where it is most needed.
[0018] FIG. 4 is a cross-sectional view of adaptive cooling
structure 40 taken at a hot spot location along line 4-4 of FIG. 2.
Liner wall 48 is deflected away from mounting support 44 due to
extreme heat caused by hot spot location 60. Hot spot location 60
is exacerbated by an area of spalled TBC layer 56. The deflection
of liner wall 48 expanded chamber 70, increasing distance L to
L+.DELTA.L at hot spot location 60 and in turn increasing ratio L/D
of distance L to diameter D of coolant apertures 62.
[0019] Cooling air A.sub.C flows through coolant apertures 62 and
enters chamber 70, impinging on second surface 54. Cooling air
A.sub.C exits first surface 52 through film apertures 50 in liner
wall 48, forming a film. Impingement effectiveness is increased at
hot spot location 60 as a result of the deflection of liner 48 away
from mounting support 44. As discussed in relation to FIG. 3, the
fabrication of adaptive cooling structure 40 with a ratio L/D lower
than the preferred ratio of three provides for increased
impingement effectiveness when the deflection of liner wall 48 at
hot spot location 60 increases distance L to L+.DELTA.L. Thus, the
preferred increased ratio L/D resulting from the deflection of
liner wall 48 is between three and 3.5, which results in a
preferred impingement heat transfer coefficient. In alternative
embodiments, the increased ratio L/D ratio can be between
approximately one and four or between two and four.
[0020] FIG. 5 is a graph of ratio L/D versus impingement
effectiveness H including preferred impingement effectiveness range
72. If as-fabricated adaptive cooling structure 40 has ratio L/D in
range 74, less than approximately three, the deflection of liner
wall 48 in hot spot location 60 will increase the impingement
effectiveness to range 72. If as-fabricated adaptive cooling
structure 40 were to have ratio L/D equal to or greater than three,
the deflection of liner wall 48 in hot spot location 60 would
result in decreased impingement effectiveness range 76. Thus, the
present invention is specifically designed so the deflection of
liner wall 48 results in ratio L/D in preferred impingement
effectiveness range 72. Impingement effectiveness range 72 can have
L/D of between one and four, between two and four, or between 2.5
and 3.5. As discussed in relation to FIG. 3, the preferred
as-fabricated range 74 has ratio L/D of between approximately two
and three, but can be anything less than three. In one embodiment,
decreased impingement effectiveness range 76 has ratio L/D of
anything above four.
[0021] While the invention has been described with reference to an
exemplary embodiment(s), it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
* * * * *