U.S. patent application number 13/359691 was filed with the patent office on 2013-08-01 for gas turbine pattern swirl film cooling.
The applicant listed for this patent is Adebukola O. Benson, Gary Michael Itzel, Xiuzhang James Zhang. Invention is credited to Adebukola O. Benson, Gary Michael Itzel, Xiuzhang James Zhang.
Application Number | 20130195650 13/359691 |
Document ID | / |
Family ID | 47631309 |
Filed Date | 2013-08-01 |
United States Patent
Application |
20130195650 |
Kind Code |
A1 |
Benson; Adebukola O. ; et
al. |
August 1, 2013 |
Gas Turbine Pattern Swirl Film Cooling
Abstract
A turbine airfoil includes a blade having a leading and trailing
edges and an internal cooling circuit, and a plurality of film
holes extending between the internal cooling circuit and an
exterior of the blade. The plurality of film holes are shaped to
generate a swirling flow exiting the film holes adjacent the
leading edge to thereby enhance local convection and provide an
insulating barrier to gaspath flow.
Inventors: |
Benson; Adebukola O.;
(Greenville, SC) ; Zhang; Xiuzhang James;
(Greenville, SC) ; Itzel; Gary Michael;
(Greenville, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Benson; Adebukola O.
Zhang; Xiuzhang James
Itzel; Gary Michael |
Greenville
Greenville
Greenville |
SC
SC
SC |
US
US
US |
|
|
Family ID: |
47631309 |
Appl. No.: |
13/359691 |
Filed: |
January 27, 2012 |
Current U.S.
Class: |
416/1 ;
416/97R |
Current CPC
Class: |
F05D 2250/25 20130101;
F05D 2260/202 20130101; F05D 2240/303 20130101; F01D 5/187
20130101 |
Class at
Publication: |
416/1 ;
416/97.R |
International
Class: |
F01D 5/18 20060101
F01D005/18 |
Claims
1. A turbine airfoil comprising: a blade including a pressure
sidewall and a suction sidewall joined together at chordally
opposite leading and trailing edges; at least one cooling hole
disposed between the pressure sidewall and the suction sidewall
adjacent the leading edge; and a plurality of curved film holes
extending between the at least one cooling hole and an exterior of
the blade.
2. A turbine airfoil according to claim 1, wherein the curved film
holes are helical.
3. A turbine airfoil according to claim 2, wherein the plurality of
helical film holes are oriented in clockwise and counter-clockwise
directions.
4. A turbine airfoil according to claim 2, wherein adjacent ones of
the plurality of helical film holes are oriented in opposite
directions.
5. A turbine airfoil according to claim 2, wherein first groups of
the helical film holes are oriented in one direction and second
groups of the helical film holes are oriented in an opposite
direction.
6. A turbine airfoil according to claim 5, wherein the first groups
and second groups alternate along a length of the blade.
7. A turbine airfoil according to claim 5, wherein each of the
first and second groups comprises three helical film holes.
8. A turbine airfoil according to claim 2, wherein at least one of
the plurality of helical film holes comprises a double helical film
hole.
9. A turbine airfoil comprising: a blade having a leading edge and
a trailing edge and including an internal cooling circuit; and a
plurality of film holes extending between the internal cooling
circuit and an exterior of the blade, the plurality of film holes
being shaped to generate a swirling flow exiting the film holes
adjacent the leading edge to thereby enhance local convection and
provide an insulating barrier to gaspath flow.
10. A turbine airfoil according to claim 9, wherein the plurality
of film holes are helical film holes.
11. A turbine airfoil according to claim 10, wherein the helical
film holes are oriented in clockwise and counter-clockwise
directions.
12. A turbine airfoil according to claim 10, wherein adjacent ones
of the helical film holes are oriented in opposite directions.
13. A turbine airfoil according to claim 10, wherein first groups
of the helical film holes are oriented in one direction and second
groups of the helical film holes are oriented in an opposite
direction.
14. A turbine airfoil according to claim 13, wherein the first
groups and second groups alternate along a length of the blade.
15. A turbine airfoil according to claim 13, wherein each of the
first and second groups comprises three helical film holes.
16. A turbine airfoil according to claim 9, wherein at least one of
the helical film holes comprises a double helical film hole.
17. A method of film cooling a turbine airfoil including a blade
with a leading edge and a trailing edge and having an internal
cooling circuit, the method comprising: delivering cooling air to
the internal cooling circuit; and flowing the cooling air from the
internal cooling circuit through a plurality of film holes
extending between the internal cooling circuit and an exterior of
the blade, the flowing step comprising swirling the cooling air in
the film holes and thereby providing an insulating barrier to
gaspath flow.
18. A method according to claim 17, wherein the plurality of film
holes comprise helical film holes, and wherein the flowing step is
practiced by flowing the cooling air from the internal cooling
circuit through the helical film holes.
Description
BACKGROUND OF THE INVENTION
[0001] This application relates generally to gas turbine engines
and, more particularly, to methods and apparatus for film cooling
airfoils used within gas turbine engines.
[0002] Gas turbine engines typically include a compressor, a
combustor, and a turbine. Airflow entering the compressor is
compressed and directed to the combustor where it is mixed with
fuel and ignited, producing hot combustion gases used to drive the
turbine. Blades and vanes used in the turbine section of a gas
turbine engine each have an airfoil section that extends radially
across an engine flowpath. During engine operation, the turbine
blades and vanes are exposed to elevated temperatures that can lead
to mechanical failure and corrosion. Therefore, it is common
practice to make the blades and vanes from a temperature tolerant
alloy and to apply corrosion resistant and thermally insulating
coatings to the airfoil and other flowpath exposed surfaces. It is
also widespread practice to cool the airfoils by flowing a coolant
through the interior of the airfoils.
[0003] For example, a turbine vane or rotor blade typically
includes a hollow airfoil, the outside of which is exposed to the
hot combustion gases, and the inside of which is supplied with
cooling fluid, which is typically compressed air. The airfoil
includes leading and trailing edges, a pressure side, and a suction
side. The pressure and suction sides connect at the airfoil leading
and trailing edges, and span radially between an airfoil root and
an airfoil tip. Film cooling holes extend between an internal
cooling circuit defined within the airfoil and an outer surface of
the airfoil. The film cooling holes route cooling fluid from the
internal cooling circuit to the outside of the airfoil for film
cooling the airfoil.
[0004] Helical ribs in cooling holes have been used to generate a
secondary flow pair of longitudinal vortices in the same direction
as the turn of the rib. It may be desirable to utilize this known
behavior in film holes to improve film cooling, increase coverage
for film cooling and augment cooling efficiency.
BRIEF DESCRIPTION OF THE INVENTION
[0005] In an exemplary embodiment, a turbine airfoil includes a
blade with a pressure sidewall and a suction sidewall joined
together at chordally opposite leading and trailing edges, and at
least one cooling hole disposed between the pressure sidewall and
the suction sidewall adjacent the leading edge. A plurality of
curved film holes extend between the at least one cooling hole and
an exterior of the blade.
[0006] In another exemplary embodiment, a turbine airfoil includes
a blade having a leading and trailing edges and an internal cooling
circuit, and a plurality of film holes extending between the
internal cooling circuit and an exterior of the blade. The
plurality of film holes are shaped to generate a swirling flow
exiting the film holes adjacent the leading edge to thereby enhance
local convection and provide an insulating barrier to gaspath
flow.
[0007] In yet another exemplary embodiment, a method of film
cooling a turbine airfoil includes the steps of delivering cooling
air to the internal cooling circuit, and flowing the cooling air
from the internal cooling circuit through a plurality of film holes
extending between the internal cooling circuit and an exterior of
the blade. The flowing step comprises swirling the cooling air in
the film holes and thereby providing an insulating barrier to
gaspath flow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of a blade portion of a turbine
airfoil;
[0009] FIG. 2 shows an exemplary arrangement of helical film holes;
and
[0010] FIG. 3 shows a double helical film hole.
DETAILED DESCRIPTION OF THE INVENTION
[0011] Film-cooling holes or film holes are widely used in modern
gas turbines to cool the turbine airfoils that are exposed to hot
combustion gases during operation of the turbine. The film-cooling
holes provide cooling of the airfoil in several ways. Firstly, they
provide film-cooling of the airfoil surface. Film-cooling is the
cooling of a body or surface by maintaining a thin fluid layer over
the affected area of a fluid that has a lower temperature than the
operating environment. The fluid film insulates the film-cooled
surface from the external operating environment, thereby reducing
convective heat transfer from the external operating environment
into the airfoil. Further, the film of the cooling fluid also
removes heat from the airfoil surface. Secondly, film-cooling also
provides convective heat transfer from and cooling of the airfoil
sidewall surrounding the film-cooling hole as the cooling air flows
through it along the length of the hole. Thirdly, the film-cooling
holes remove heat by providing an exhaust path for the cooling air
that has been heated as it in turn cools the airfoil by passage
through the airfoil cooling circuit.
[0012] FIG. 1 shows a blade section 10 of a turbine airfoil. The
blade includes a pressure sidewall 12 and a suction sidewall 14
joined together at chordally opposite leading 16 and trailing 18
edges. A cooling circuit is defined by a plurality of cooling
passages or holes 20 that are disposed between the pressure
sidewall 12 and the suction sidewall 14. At least one cooling hole
21 is positioned adjacent the leading edge 16.
[0013] Film holes or film cooling holes are known that extend from
one or more of the cooling holes 20 to an exterior of the blade.
The film cooling holes are typically straight and direct cooling
air from the cooling holes 20 to the blade exterior. With continued
reference to FIG. 1, and with reference to FIG. 2, the airfoil
according to preferred embodiments includes a plurality of curved
film holes 22 that extend between the cooling hole 21 and the
exterior of the blade 10. That is, a passage between the cooling
hole 21 and the exterior of the blade 10 comprises a curved or
twisted groove or the like such that air flowing through and
exiting the film holes 22 is turning. An exemplary shape for the
film holes may be helical, although other shapes may be
contemplated, and the invention is not necessarily meant to be
limited to the arrangement shown in the drawings. With the helical
or other curved or twisted shaped film holes 22, the film flow
coming out of the holes no longer has a direct path, but rather
exits in a swirling pattern, resulting in enhanced local convection
with the holes as well as providing an insulating barrier to the
gas path flow.
[0014] Preferably, the helical film holes 22 are oriented in both
clockwise and counter-clockwise directions. Adjacent ones of the
plurality of helical film holes 22 may thus be oriented in opposite
directions. As a consequence of such structure, the exiting flow
swirls in opposite vortices, further enhancing the advantageous
effects of the design. As shown in FIG. 2, in an exemplary
embodiment, a first group 24 of the helical film holes 22 may be
oriented in one direction, while a second group 26 is oriented in
an opposite direction. As shown, the first groups 24 and second
groups 26 may alternate along a length of the blade 10. In the
embodiment shown in FIG. 2, each of the first and second groups 24,
26 comprises three helical film holes 22.
[0015] In yet another exemplary construction, with reference to
FIG. 3, at least one of the helical film holes may comprise a
double helical film hole 220. That is, the film hole 220 may
comprise two (or more) interlaced helical grooves or passageways
through which cooling air is passed.
[0016] The cooling circuit with helical film holes serves to
improve film cooling, increase coverage for film cooling and
generally augment cooling efficiency. The swirling flow provides
for enhanced local convection within the holes and also provides an
insulating barrier to the gaspath flow.
[0017] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiments, it is to be understood that the invention is not to be
limited to the disclosed embodiments, but on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims.
* * * * *