U.S. patent application number 10/981466 was filed with the patent office on 2006-05-11 for aspherical dimples for heat transfer surfaces and method.
Invention is credited to Olivier Bibor, Timothy Blaskovich, Michael Leslie Clyde Papple, Toufik Djeridane, Larry Lebel, Phillip Ligrani, Sri Sreekanth, Ricardo Trindade.
Application Number | 20060099073 10/981466 |
Document ID | / |
Family ID | 36316505 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060099073 |
Kind Code |
A1 |
Djeridane; Toufik ; et
al. |
May 11, 2006 |
Aspherical dimples for heat transfer surfaces and method
Abstract
A dimple for use on a heat transfer surface exposed to a flowing
gas, for use for example in a gas turbine engine, the dimple having
an aspherical shape.
Inventors: |
Djeridane; Toufik; (St.
Bruno, CA) ; Blaskovich; Timothy; (Montreal, CA)
; Sreekanth; Sri; (Mississauga, CA) ; Trindade;
Ricardo; (Coventry, CT) ; Clyde Papple; Michael
Leslie; (Ile des Soeurs, CA) ; Bibor; Olivier;
(Montreal, CA) ; Lebel; Larry; (Sherbrooke,
CA) ; Ligrani; Phillip; (Sandy, UT) |
Correspondence
Address: |
BACHMAN & LAPOINTE, P.C. (PWC)
900 CHAPEL STREET
SUITE 1201
NEW HAVEN
CT
06510-2814
US
|
Family ID: |
36316505 |
Appl. No.: |
10/981466 |
Filed: |
November 5, 2004 |
Current U.S.
Class: |
416/97R |
Current CPC
Class: |
F28F 13/12 20130101;
F05D 2260/202 20130101; F05D 2260/2212 20130101; F05D 2260/22141
20130101; F05D 2250/61 20130101; F28F 3/044 20130101; F01D 5/186
20130101; F05D 2250/28 20130101; F05D 2260/2214 20130101 |
Class at
Publication: |
416/097.00R |
International
Class: |
F01D 5/18 20060101
F01D005/18 |
Claims
1. A gas turbine engine component comprising: a turbine portion
exposed, in use, to a hot fluid flow; at least one cooling passage
disposed within the turbine portion, the passage having a surface;
and a plurality of aspherically-shaped dimple provided on the
surface.
2. The gas turbine engine component of claim 1, wherein at least
some of the dimples have a generally circular rim, said rim being
an interface between the dimples and the surface.
3. The gas turbine engine component of claim 1, wherein at least
some of the dimples have a generally acircular rim, said rim being
an interface between the dimples and the surface.
4. The gas turbine engine component of claim 1, wherein at least
some of the dimples have a ratio between a maximum depth and a
maximum diameter of less than 0.2.
5. The gas turbine engine component of claim 4, wherein the ratio
is substantially equal to 0.1.
6. The gas turbine engine component of claim 1, wherein at least
some of the dimples have a substantially flat bottom surface.
7. The gas turbine engine component of claim 1, wherein at least
some of the dimples have a bottom surface substantially shaped as a
segment of torus.
8. The gas turbine engine component of claim 1, wherein at least
some of the dimples have a bottom surface shaped as a double wedge
with a substantially flat bottom surface.
9. An airfoil for use in a gas turbine engine, the airfoil having
at least one internal cooling passage therein adapted to direct a
cooling fluid flow therethrough, the airfoil comprising: a
plurality of aspherical dimples disposed on at least one internal
surface of the passage.
10. The airfoil of claim 9, wherein at least some of the dimples
have a generally circular rim, said rim being an interface between
the dimples and the surface.
11. The airfoil of claim 9, wherein at least some of the dimples
have a generally acircular rim, said rim being an interface between
the dimples and the surface.
12. The airfoil of claim 9, wherein at least some of the dimples
have a ratio between a maximum depth and a maximum diameter of less
than 0.2.
13. The airfoil of claim 12, wherein the ratio is substantially
equal to 0.1.
14. The airfoil of claim 9, wherein at least some of the dimples
have a substantially flat bottom surface.
15. The airfoil of claim 9, wherein at least some of the dimples
have a bottom surface substantially shaped as a segment of
torus.
16. The airfoil of claim 9, wherein at least some of the dimples
have a bottom surface shaped as a double wedge with a substantially
flat bottom surface.
17. A heat transfer dimple for use on a surface exposed, in use, to
a flowing gas, the dimple having an aspherical shape.
18. The heat transfer dimple of claim 17, wherein the dimple has a
generally circular rim, said rim being an interface between the
dimple and the surface.
19. The heat transfer dimple of claim 17, wherein the dimple has a
generally acircular rim, said rim being an interface between the
dimple and the surface.
20. The heat transfer dimple of claim 17, wherein the dimple has a
ratio between a maximum depth and a maximum diameter of less than
0.2.
21. The heat transfer dimple of claim 20, wherein the ratio is
substantially equal to 0.1.
22. The heat transfer dimple of claim 17, wherein the dimple has a
substantially flat bottom surface.
23. The heat transfer dimple of claim 17, wherein the dimple has a
bottom surface substantially shaped as a segment of torus.
24. The heat transfer dimple of claim 17, wherein the dimple has a
bottom surface shaped as a double wedge with a substantially flat
bottom surface.
25. A shaped surface for use in a gas turbine engine to create
turbulences in a gas when the gas flows thereon, the surface
comprising a plurality of aspherical dimples.
26. The surface of claim 25, wherein at least some of the dimples
have a generally circular rim, said rim being an interface between
the dimples and the surface.
27. The surface of claim 25, wherein at least some of the dimples
have a generally acircular rim, said rim being an interface between
the dimples and the surface.
28. The surface of claim 25, wherein at least some of the dimples
have a ratio between a maximum depth and a maximum diameter of less
than 0.2.
29. The surface of claim 28, wherein the ratio is substantially
equal to 0.1.
30. The surface of claim 25, wherein at least some of the dimples
have a substantially flat bottom surface.
31. The surface of claim 25, wherein at least some of the dimples
have a bottom surface substantially shaped as a segment of
torus.
32. The surface of claim 25, wherein at least some of the dimples
have a bottom surface shaped as a double wedge with a substantially
flat bottom surface.
33. A method of promoting heat transfer, the method comprising:
providing a plurality of aspherical dimples on a surface; and
directing a gas over the surface, the gas having a temperature
being different than that of the surface.
34. The method of claim 33, wherein the dimples induce increased
turbulence in the flow and thereby promote heat transfer.
35. A method of inducing turbulence in a gas flowing inside a gas
turbine engine, the method comprising: providing a plurality of
aspherical dimples on a surface; and directing the gas over the
surface.
Description
TECHNICAL FIELD
[0001] The invention relates generally to shaped dimples for use in
heat transfer surfaces such as, for example, those employed in
cooling gas turbine engines.
BACKGROUND OF THE ART
[0002] In heat transfer technologies, dimples are small depressions
provided on a heat transfer surface to create or amplify localised
turbulences in the boundary layer of a gas flowing over the
surface. Many dimples are generally provided on a same surface. One
purpose of this turbulence is to increase the heat transfer between
the gas and the surface on which the dimples are provided. This is
often used, for example, in internal airfoil cooling or combustor
cooling in gas turbine engines. Dimples can also be used for other
purposes, however the purpose affects dimple placement,
arrangement, etc.
[0003] FIG. 3 illustrates a typical heat transfer dimple as found
in the prior art. This dimple is semi-spherical, namely that its
bottom surface is shaped as a segment of a sphere. It comprises a
bottom surface having a radius of curvature r. The ratio between
the maximum depth (.delta.) and the maximum diameter (D) is
generally 0.2 or more.
[0004] As there is a constant need for more efficient and reliable
gas turbine engines, there is consequently a constant need for new
features and methods that allow reaching these goals, such as
improvements in the field of heat transfer.
SUMMARY OF THE INVENTION
[0005] In one aspect, the present invention provides a gas turbine
engine component comprising a turbine portion exposed, in use, to a
hot fluid flow; at least one cooling passage disposed within the
turbine portion, the passage having a surface; and a plurality of
aspherically-shaped dimple provided on the surface.
[0006] In another aspect, the present invention provides an airfoil
for use in a gas turbine engine, the airfoil having at least one
internal cooling passage therein adapted to direct a cooling fluid
flow therethrough, the airfoil comprising a plurality of aspherical
dimples disposed on at least one internal surface of the
passage.
[0007] In another aspect, the present invention provides a heat
transfer dimple for use on a surface exposed, in use, to a flowing
gas, the dimple having an aspherical shape.
[0008] In another aspect, the present invention provides a shaped
surface for use in a gas turbine engine to create turbulences in a
gas when the gas flows thereon, the surface comprising a plurality
of aspherical dimples.
[0009] In another aspect, the present invention provides a method
of promoting heat transfer, the method comprising: providing a
plurality of aspherical dimples on a surface; and directing a gas
over the surface, the gas having a temperature being different than
that of the surface.
[0010] In another aspect, the present invention provides a method
of inducing turbulence in a gas flowing inside a gas turbine
engine, the method comprising: providing a plurality of aspherical
dimples on a surface; and directing the gas over the surface.
[0011] Further details of these and other aspects of the present
invention will be apparent from the detailed description and
figures included below.
DESCRIPTION OF THE DRAWINGS
[0012] Reference is now made to the accompanying figures depicting
aspects of the present invention, in which:
[0013] FIG. 1 shows a generic gas turbine engine to illustrate an
example of a general environment in which the invention can be
used.
[0014] FIG. 2 is a schematic top plan view of a generic heat
transfer surface on which dimples are provided.
[0015] FIG. 3 is a cross-sectional view of a spherical dimple, as
found in the prior art.
[0016] FIGS. 4a, 4b and 4c are schematic views of an aspherical
dimple in accordance with one preferred embodiment of the present
invention.
[0017] FIGS. 5a, 5b and 5c are schematic views of an aspherical
dimple in accordance with another preferred embodiment of the
present invention.
[0018] FIGS. 6a, 6b and 6c are schematic views of an aspherical
dimple in accordance with yet another preferred embodiment of the
present invention.
DETAILED DESCRIPTION
[0019] FIG. 1 illustrates an example of a gas turbine engine 10 of
a type preferably provided for use in subsonic flight, generally
comprising in serial flow communication a fan 12 through which
ambient air is propelled, a multistage compressor 14 for
pressurizing the air, a combustor 16 in which the compressed air is
mixed with fuel and ignited for generating an annular stream of hot
combustion gases, and a turbine section 18 for extracting energy
from the combustion gases. This figure illustrates an example of
the environment in which the present invention can be used.
[0020] FIG. 2 schematically illustrates a generic surface 20 in
which a plurality of dimples 30 are provided. Such surface 20 can
be present in various components of the gas turbine engine 10, for
instance in the internal cooling paths of airfoils or in some areas
of the combustor 16. Although the illustrated surface 20 appears to
be flat, dimples 30 can be provided on surfaces 20 of about any
shape and configuration.
[0021] Dimples 30 are small and usually shallow depressions. They
are usually made directly within the material of the surface 20 in
which they are located. Traditionally, the dimples 30 were shaped
as segments of sphere. FIG. 3 shows an example of a spherical
dimple 30'.
[0022] During operation of the gas turbine engine 10, the gas
flowing on the surface 20 has a boundary layer whose flow will be
disrupted by the presence of the dimples 30. As a result,
turbulences appear in the gas flow but without causing significant
pressure losses. These turbulences increase the swirling of the gas
molecules above the surface 20, thereby increasing the heat
transfer efficiency between the gas and the surface 20.
[0023] It was found by the inventors that aspherically-shaped
dimples 30 can be used to improve the efficiency of the turbulences
compared to spherically-shaped dimples 30' (FIG. 3). These
non-spherical dimples 30 can have many possible embodiments, some
of which are shown in FIGS. 4a through 6c. Each of these preferred
embodiments have some specificities that may attract the attention
of the engineers in the design of their components.
[0024] FIGS. 4a, 4b and 4c schematically illustrate a cross section
of an aspherical dimple 30 in accordance with one preferred
embodiment. FIG. 4a illustrates a "disproportional" dimple in which
the shape has been exaggerated for illustration proposes only. The
real preferred aspect is shown in FIG. 4b. FIG. 4c shows an upper
view of the dimple 30, as shown in FIG. 4b. The dimple 30
preferably comprises a circular rim 32. The bottom surface 34 of
the dimple is preferably flat and inclined. The inclination
preferably begins at the leading side 36 with reference to the gas
flow, although any desired orientation may be used. The bottom
surface 34 intersects a corresponding inclined wall 38 at the
trailing side 40 of the dimple 30. Preferably, the ratio of the
maximum depth (.delta.) versus the maximum diameter (D) of the
dimple is less than 0.2, and more preferably being about 0.1.
[0025] FIGS. 5a, 4b and 4c schematically illustrate a cross section
of an aspherical dimple 30 in accordance with another embodiment.
FIG. 5a illustrates a "disproportional" dimple 30 for illustration
purposes. The real preferred aspect is shown in FIG. 5b. FIG. 5c
shows an upper view of the dimple 30, as shown in FIG. 5b. The
dimple 30 preferably comprises a circular rim 32 and a central
circular raised portion 42 with a flat upper surface 44 which is at
the same level than the main surface 20. The raised portion 42 has
a diameter D' that is preferably about a quarter of the diameter D
of the dimple 30. The bottom surface 34 of the dimple 30 is
substantially shaped as a segment of torus (or donut). Preferably,
the ratio of the maximum depth (.delta.) versus the maximum
diameter (D) of the dimple is less than 0.2, and more preferably
being about 0.1.
[0026] FIGS. 6a, 4b and 4c schematically illustrate a cross section
of an aspherical dimple 30 in accordance with another embodiment.
FIG. 6a illustrates a "disproportional" dimple 30 for illustration
purposes. The real preferred aspect is shown in FIG. 6b. FIG. 6c
shows an upper view of the dimple 30, as shown in FIG. 6b. The
dimple 30 is preferably shaped as a double wedge with a
substantially flat bottom surface 34. The double wedge forms an
arrow-like shape which is preferably pointed towards the upstream
side of the gas flow, although any desired orientation may be used.
The bottom surface 34 of the dimple 30 is substantially flat and
inclined, starting from the leading side 36 with reference to the
gas flow and up to the trailing side 40. Preferably, the ratio of
the maximum depth (.delta.) versus the maximum diameter (D) of an
imaginary circle 50, in which the arrow is positioned, is less than
0.2, and more preferably being about 0.1. This dimple itself
otherwise has an acircular rim.
[0027] As can be appreciated, the aspherical dimples 30 will allow
engineers designing devices in which it is possible to enhance heat
transfer or induce more effective turbulences when exposed to a gas
flowing on a surface having several of these dimples 30.
[0028] The above description is meant to be exemplary only, and one
skilled in the art will recognize that changes may be made to the
embodiments described without department from the scope of the
invention disclosed. For example, other aspherical shapes can be
used, and the ones disclosed herein are exemplary only. The
orientations of the exemplary dimples relative to the direction of
flow thereover may be any desired, and need not be as described.
The ratio between the maximum depth and the maximum diameter of the
dimples can be equal or more than 0.2, although a lesser value is
believed to be more advantageous where pressure losses caused by
the dimple are important, as they are in the filed of gas turbine
cooling. Also, aspherical dimples need not be employed exclusively,
not one type of aspherical dimples employed, but rather a plurality
of types and sizes may be employed, and can be used in conjunction
with spherical dimples 30', if desired. Although the present
invention has been described with respect to its application to gas
turbine engines, the skilled reader will appreciate that the
invention has board application to many different types of heat
transfer environments and applications. Still other modifications
which fall within the scope of the present invention will be
apparent to those skilled in the art, in light of a review of this
disclosure, and such modifications are intended to fall within the
appended claims.
* * * * *