Aspherical dimples for heat transfer surfaces and method
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.
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 ARTIn 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.
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 INVENTIONIn 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.
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.
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.
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.
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.
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.
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 DRAWINGSReference is now made to the accompanying figures depicting aspects of the present invention, in which:
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.
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.
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′ (
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.
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.
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.
Type: Application
Filed: Nov 5, 2004
Publication Date: May 11, 2006
Inventors: Toufik Djeridane (St. Bruno), Timothy Blaskovich (Montreal), Sri Sreekanth (Mississauga), Ricardo Trindade (Coventry, CT), Michael Clyde Papple (Ile des Soeurs), Olivier Bibor (Montreal), Larry Lebel (Sherbrooke), Phillip Ligrani (Sandy, UT)
Application Number: 10/981,466
International Classification: F01D 5/18 (20060101);