Title:
INTERNAL COOLING SYSTEM WITH CORRUGATED INSERT FORMING NEARWALL COOLING CHANNELS FOR AIRFOIL USABLE IN A GAS TURBINE ENGINE
Kind Code:
A1


Abstract:
An airfoil for a gas turbine engine in which the airfoil includes an internal cooling system formed from one or more midchord cooling channels with a corrugated insert positioned therein and creating nearwall leading edge, pressure side and suction side nearwall cooling channels. The corrugated insert may be formed from a wall that oscillates in a repeating pattern between peaks and valleys, such that the peaks are closer to an inner surface of the outer wall forming the generally elongated hollow airfoil The corrugated insert may work in concert with the rows of partition walls to create periodic impingement on the inner surface of the outer wall Such cooling system provides adequate cooling for use in environments in which few, if any, cooling holes are desired, such as in crude oil engine applications



Inventors:
Lee, Ching-pang (Cincinnati, OH, US)
Um, Jae Y. (Winter Garden, FL, US)
Hillier, Gerald L. (Charlottesville, VA, US)
Schroeder, Eric (Loveland, OH, US)
Abdullah, Mohamed (Cincinnati, OH, US)
Application Number:
14/155422
Publication Date:
07/16/2015
Filing Date:
01/15/2014
Assignee:
Siemens Energy, Inc. (Orlando, FL, US)
Primary Class:
Other Classes:
415/175
International Classes:
F01D9/02; F01D5/18
View Patent Images:
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Primary Examiner:
YOUNGER, SEAN JERRARD
Attorney, Agent or Firm:
SIEMENS CORPORATION (Orlando, FL, US)
Claims:
We claim:

1. A turbine airfoil, comprising: a generally elongated hollow airfoil formed from an outer wall, and having a leading edge, a trailing edge, a pressure side, a suction side, and a cooling system positioned within interior aspects of the generally elongated hollow airfoil; at least one midchord cooling channel with at least one corrugated insert positioned therein and creating a leading edge nearwall cooling channel between the leading edge and the corrugated insert, a suction side nearwall cooling channel between the suction side and the corrugated insert and a pressure side nearwall cooling channel between the pressure side and the corrugated insert; wherein the corrugated insert is formed from a wall that oscillates in a repeating pattern between peaks and valleys, such that the peaks are closer to an inner surface of the outer wall forming the generally elongated hollow airfoil; a plurality of rows of partition walls extending from the inner surface forming the outer wall and into the midchord cooling channel, wherein the partition walls include gaps therein and wherein the rows of partition walls are generally aligned with a direction of cooling fluid flow from the leading edge chordwise toward the trailing edge; and wherein at least a portion of the peaks in the corrugated insert extending radially outward are aligned with the gaps within at least a portion of at least one partition wall

2. The turbine airfoil of claim 1, wherein at least one partition wall includes gaps therein that extend an entire length of the at least one partition wall

3. The turbine airfoil of claim 1, wherein at least one partition wall is linear.

4. The turbine airfoil of claim 1, wherein each of the partition walls is linear and each of the partition walls are parallel with each other.

5. The turbine airfoil of claim 1, wherein at least one partition wall is formed from a first and second subpartition walls, wherein the second subpartition wall is offset laterally from first subpartition wall and wherein the first and second subpartition walls are staggered in an alternating manner moving in a direction from the leading edge toward the trailing edge.

6. The turbine airfoil of claim 1, wherein each partition wall is formed from a first and second subpartition walls, wherein the second subpartition wall is offset laterally from first subpartition wall and wherein the first and second subpartition walls are staggered in an alternating manner moving in a direction from the leading edge toward the trailing edge.

7. The turbine airfoil of claim 6, wherein a second subpartition wall is positioned along an axis that is equidistant from a first subpartition wall within a same partition wall as the second subpartition wall and a first subpartition wall within an adjacent partition wall.

8. The turbine airfoil of claim 1, further comprising a plurality of miniribs extend from the inner surface forming the outer wall and extending between adjacent partition walls, wherein the miniribs are nonparallel with the partition walls and are shorter in height extending from the inner surface than adjacent partition walls

9. The turbine airfoil of claim 8, wherein the plurality of miniribs are aligned with each other and are orthogonal to the adjacent partition walls

10. The turbine airfoil of claim 1, further comprising at least one trailing edge cooling channel positioned between the at least one midchord cooling channel and the trailing edge of the generally elongated hollow airfoil, wherein the at least one trailing edge cooling channel includes a plurality of pin fins extending from the outer wall forming the pressure side to the suction side and forming zigzag cooling flow channels within the at least one trailing edge cooling channel

11. The turbine airfoil of claim 10, wherein at least a portion of the pin fins have cross-sectional areas with a leading edge, a trailing edge that is positioned on a downstream corner and separated from the leading edge by a concave side surface and a convex side surface

12. The turbine airfoil of claim 11, wherein at least one of the zigzag cooling flow channels is formed from a plurality of pin fins aligned such that the concave and convex side surfaces alternate moving towards the trailing edge.

13. The turbine airfoil of claim 11, wherein a first upstream pin fin has a cross-sectional area formed from an upstream section and a downstream section, wherein the upstream section is generally linear with a constant width, and the downstream section is generally linear with a tapered width that reduces in width moving towards the trailing edge, wherein the upstream and downstream sections are nonlinear and nonorthogonal with each other

14. A turbine airfoil, comprising: a generally elongated hollow airfoil formed from an outer wall, and having a leading edge, a trailing edge, a pressure side, a suction side, and a cooling system positioned within interior aspects of the generally elongated hollow airfoil; at least one midchord cooling channel with at least one corrugated insert positioned therein and creating a leading edge nearwall cooling channel between the leading edge and the corrugated insert, a suction side nearwall cooling channel between the suction side and the corrugated insert and a pressure side nearwall cooling channel between the pressure side and the corrugated insert; wherein the corrugated insert is formed from a wall that oscillates in a repeating pattern between peaks and valleys, such that the peaks are closer to an inner surface of the outer wall forming the generally elongated hollow airfoil; a plurality of rows of partition walls extending from the inner surface forming the outer wall and into the midchord cooling channel, wherein the partition walls include gaps therein and wherein the rows of partition walls are generally aligned with a direction of cooling fluid flow from the leading edge chordwise toward the trailing edge; wherein at least a portion of the peaks in the corrugated insert extending radially outward are aligned with the gaps within at least a portion of at least one partition wall; a plurality of miniribs extending from the inner surface forming the outer wall and extending between adjacent partition walls, wherein the miniribs are nonparallel with the partition walls and are shorter in height extending from the inner surface than adjacent partition walls; at least one trailing edge cooling channel positioned between the at least one midchord cooling channel and the trailing edge of the generally elongated hollow airfoil, wherein the at least one trailing edge cooling channel includes a plurality of pin fins extending from the outer wall forming the pressure side to the suction side and forming zigzag cooling flow channels within the at least one trailing edge cooling channel; and wherein at least a portion of the pin fins have cross-sectional areas with a leading edge, a trailing edge that is positioned on a downstream corner and separated from the leading edge by a concave side surface and a convex side surface

15. The turbine airfoil of claim 14, wherein each of the partition walls is linear and each of the partition walls is parallel with each other.

16. The turbine airfoil of claim 14, wherein each partition wall is formed from a first and second subpartition walls, wherein the second subpartition wall is offset laterally from first subpartition wall and wherein the first and second subpartition walls are staggered in an alternating manner moving in a direction from the leading edge toward the trailing edge.

17. The turbine airfoil of claim 16, wherein a second subpartition wall is positioned along an axis that is equidistant from a first subpartition wall within a same partition wall as the second subpartition wall and a first subpartition wall within an adjacent partition wall

18. The turbine airfoil of claim 14, wherein the miniribs are aligned with each other and are orthogonal to the adjacent partition walls.

19. The turbine airfoil of claim 14, wherein a first upstream pin fin has a cross-sectional area formed from an upstream section and a downstream section, wherein the upstream section is generally linear with a constant width, and the downstream section is generally linear with a tapered width that reduces in width moving towards the trailing edge, wherein the upstream and downstream sections are nonlinear and nonorthogonal with each other and wherein at least one of the zigzag cooling flow channels is formed from a plurality of pin fins aligned such that the concave and convex side surfaces alternate moving towards the trailing edge.

20. A turbine airfoil, comprising: a generally elongated hollow airfoil formed from an outer wall, and having a leading edge, a trailing edge, a pressure side, a suction side, and a cooling system positioned within interior aspects of the generally elongated hollow airfoil; at least one midchord cooling channel with at least one corrugated insert positioned therein and creating a leading edge nearwall cooling channel between the leading edge and the corrugated insert, a suction side nearwall cooling channel between the suction side and the corrugated insert and a pressure side nearwall cooling channel between the pressure side and the corrugated insert; wherein the corrugated insert is formed from a wall that oscillates in a repeating pattern between peaks and valleys, such that the peaks are closer to an inner surface of the outer wall forming the generally elongated hollow airfoil; a plurality of rows of partition walls extending from the inner surface forming the outer wall and into the midchord cooling channel, wherein the partition walls include gaps therein and wherein the rows of partition walls are generally aligned with a direction of cooling fluid flow from the leading edge chordwise toward the trailing edge; wherein at least a portion of the peaks in the corrugated insert extending radially outward are aligned with the gaps within at least a portion of at least one partition wall; wherein each partition wall is formed from a first and second subpartition walls, wherein the second subpartition wall is offset laterally from first subpartition wall and wherein the first and second subpartition walls are staggered in an alternating manner moving in a direction from the leading edge toward the trailing edge; a plurality of miniribs extending from the inner surface forming the outer wall and extending between adjacent partition walls, wherein the miniribs are nonparallel with the partition walls and are shorter in height extending from the inner surface than adjacent partition walls; at least one trailing edge cooling channel positioned between the at least one midchord cooling channel and the trailing edge of the generally elongated hollow airfoil, wherein the at least one trailing edge cooling channel includes a plurality of pin fins extending from the outer wall forming the pressure side to the suction side and forming zigzag cooling flow channels within the at least one trailing edge cooling channel; wherein at least a portion of the pin fins have cross-sectional areas with a leading edge, a trailing edge that is positioned on a downstream corner and separated from the leading edge by a concave side surface and a convex side surface; and wherein the upstream and downstream sections are nonlinear and nonorthogonal with each other and wherein at least one of the zigzag cooling flow channels is formed from a plurality of pin fins aligned such that the concave and convex side surfaces alternate moving towards the trailing edge.

Description:

FIELD OF THE INVENTION

This invention is directed generally to gas turbine engines, and more particularly to internal cooling systems for airfoils in gas turbine engines

BACKGROUND

Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit Typical turbine combustor configurations expose turbine vane and blade assemblies to high temperatures As a result, turbine vanes and blades must be made of materials capable of withstanding such high temperatures, or must include cooling features to enable the component to survive in an environment which exceeds the capability of the material Turbine engines typically include a plurality of rows of stationary turbine vanes extending radially inward from a shell and include a plurality of rows of rotatable turbine blades attached to a rotor assembly for turning the rotor

Typically, the turbine vanes are exposed to high temperature combustor gases that heat the airfoil. The airfoils include internal cooling systems for reducing the temperature of the airfoils. While there exist many configurations of cooling systems, there exists a need for improved cooling of gas turbine airfoils.

SUMMARY OF THE INVENTION

An airfoil for a gas turbine engine in which the airfoil includes an internal cooling system formed from one or more midchord cooling channels with a corrugated insert positioned therein and creating nearwall leading edge, pressure side and suction side nearwall cooling channels is disclosed. The corrugated insert may be formed from a wall that oscillates in a repeating pattern between peaks and valleys, such that the peaks are closer to an inner surface of an outer wall forming a generally elongated hollow airfoil of the airfoil. The corrugated insert may work in concert with the rows of partition walls to create periodic impingement on the inner surface of the outer wall, specifically the surfaces leading from the valleys to the peaks moving toward a trailing edge of the generally elongated hollow airfoil direct the fluids toward the outer wall. Such cooling system may provide adequate cooling for use in environments in which few, if any, cooling holes are desired, such as in crude oil engine applications

The turbine airfoil may be formed from a generally elongated hollow airfoil formed from an outer wall, and having a leading edge, a trailing edge, a pressure side, a suction side, and a cooling system positioned within interior aspects of the generally elongated hollow airfoil The cooling system may include one or more midchord cooling channels with one or more corrugated inserts positioned therein and creating a leading edge nearwall cooling channel between the leading edge and the corrugated insert, a suction side nearwall cooling channel between the suction side and the corrugated insert and a pressure side nearwall cooling channel between the pressure side and the corrugated insert. The corrugated insert may be formed from a wall that oscillates in a repeating pattern between peaks and valleys, such that the peaks are closer to an inner surface of the outer wall forming the generally elongated hollow airfoil. A plurality of rows of partition walls may extend from the inner surface forming the outer wall and into the midchord cooling channel. The partition walls may include gaps therein, and the rows of partition walls may be generally aligned with a direction of cooling fluid flow from the leading edge chordwise toward the trailing edge. At least a portion of the peaks in the corrugated insert extending radially outward may be aligned with the gaps within at least a portion of at least one partition wall.

In at least one embodiment, one or more partition walls may include gaps therein that extend for a portion of or in a repeating pattern for an entire length of the at least one partition wall In one embodiment, one or more partition walls may be linear In another embodiment, each of the partition walls may be linear and each of the partition walls may be parallel with each other. In yet another embodiment, one or more partition walls may be formed from first and second subpartition walls, whereby the second subpartition wall may be offset laterally from first subpartition wall, and the first and second subpartition walls may be staggered in an alternating manner moving downstream in a direction from the leading edge toward the trailing edge. In another embodiment, each partition wall may be formed from a first and second subpartition walls, whereby the second subpartition wall may be offset laterally from first subpartition wall, and the first and second subpartition walls may be staggered in an alternating manner moving in a direction from the leading edge toward the trailing edge. A second subpartition wall may be positioned along an axis that is equidistant from a first subpartition wall within a same partition wall as the second subpartition wall and from a first subpartition wall within an adjacent partition wall

The turbine airfoil may also include a plurality of miniribs extending from the inner surface forming the outer wall and extending between adjacent partition walls. The miniribs may be nonparallel with the partition walls and may be shorter in height extending from the inner surface than adjacent partition ribs. In at least one embodiment, the plurality of miniribs may be aligned with each other and may be orthogonal to the adjacent partition walls

The cooling system may also include one or more trailing edge cooling channels positioned between the midchord cooling channel and the trailing edge of the generally elongated hollow airfoil. The trailing edge cooling channel may include a plurality of pin fins extending from the outer wall forming the pressure side to the suction side and forming zigzag cooling flow channels within the trailing edge cooling channel At least a portion of the pin fins may have cross-sectional areas with a leading edge and a trailing edge that is positioned on a downstream corner and separated from the leading edge by a concave side surface and a convex side surface. At least one of the zigzag cooling flow channels may be formed from a plurality of pin fins aligned such that the concave and convex side surfaces alternate moving towards the trailing edge. In at least one embodiment, a first upstream pin fin may have a cross-sectional area formed from an upstream section and a downstream section. The upstream section may be generally linear with a constant width, and the downstream section may be generally linear with a tapered width that reduces in width moving towards the trailing edge. The upstream and downstream sections may be nonlinear and nonorthogonal with each other.

During use, cooling fluids are supplied from a compressor or other such source to the inner aspect of the corrugated insert of the internal cooling system Cooling fluids are passed through the inlets into the leading edge nearwall cooling channel where the fluids separate with a portion flowing into the pressure side nearwall cooling channel and a portion flowing into the suction side nearwall cooling channel. The peaks and valleys of the corrugated insert create periodic impingement on the inner surface of the outer wall The partition walls also direct the cooling fluids towards the trailing edge, and in at least come embodiments, create a nonlinear flow path toward the trailing edge to increase convection of heat from the outer wall to the cooling fluid The cooling fluid may be exhausted through film cooling holes at downstream ends of the pressure and suction side nearwall cooling channels.

Cooling fluids may also be passed to the trailing edge cooling channel via one or more trailing edge supply channels The cooling fluids may be metered through metering holes into the trailing edge cooling channel. The cooling fluids may flow into the zigzag cooling flow channels where the pin fins direct the cooling fluids in a nonlinear motion to the trailing edge, where the cooling fluids are exhausted. The cooling fluids in the trailing edge cooling channel receive heat from the outer wall forming the pressure and suction sides and from the pin fins.

An advantage of the internal cooling system is that the corrugated insert creates periodic impingement and sufficient cooling fluid mixing to cool the airfoil

These and other embodiments are described in more detail below

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the presently disclosed invention and, together with the description, disclose the principles of the invention

FIG. 1 is a perspective view of a turbine vane with aspects of this invention

FIG. 2 is a cross-sectional view of the turbine vane taken at section line 2-2 in FIG. 1.

FIG. 3 is a detailed view of the pressure side nearwall cooling channel.

FIG. 4 is a detailed view of the trailing edge cooling channel of the cooling system shown in FIG. 2.

FIG. 5 is a detailed view of the midchord cooling channel of the cooling system shown in FIG. 2

FIG. 6 is a side view of a three dimensional model of the cooling system within the turbine vane in FIG. 1.

FIG. 7 is a perspective view of the three dimensional model of the cooling system shown in FIG. 6.

FIG. 8 is schematic, cross-sectional diagram of a portion of the cooling system of FIG. 2.

FIG. 9 is a detail view of a portion of the cooling system taken at the detail line in FIG. 8.

FIG. 10 is a perspective view of a portion of the cooling system of FIG. 2.

FIG. 11 is a detail view of a portion of the cooling system taken at detail line 11-11 in FIG. 10.

FIG. 12 is a cross-sectional view of an alternative embodiment of the turbine vane taken at section line 2-2 in FIG. 1

FIG. 13 is a detailed view of an alternative embodiment of the pressure side nearwall cooling channel.

FIG. 14 is a detailed view of an alternative embodiment of the trailing edge cooling channel of the cooling system shown in FIG. 2.

FIG. 15 is a detailed view of an alternative embodiment of the midchord cooling channel of the cooling system shown in FIG. 2.

FIG. 16 is a perspective view of a turbine blade with aspects of this invention.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1-16, an airfoil 10 for a gas turbine engine in which the airfoil 10 includes an internal cooling system 14 formed from one or more midchord cooling channels 16 with a corrugated insert 18 positioned therein and creating nearwall leading edge, pressure side and suction side nearwall cooling channels 20, 22, 24 is disclosed The corrugated insert 18 may be formed from a wall 26 that oscillates in a repeating pattern between peaks 28 and valleys 30, such that the peaks 28 are closer to an inner surface 50 of an outer wall 32 forming a generally elongated hollow airfoil 34 of the airfoil 10 The corrugated insert 18 may work in concert with the rows 36 of partition walls 38 to create periodic impingement on the inner surface 50 of the outer wall 32, specifically the surfaces 40 leading from the valleys 30 to the peaks 28 moving toward a trailing edge 42 of the generally elongated hollow airfoil 34 direct the fluids toward the outer wall 32 Such cooling system 14 may provide adequate cooling for use in environments in which few, if any, cooling holes are desired, such as in crude oil engine applications.

In at least one embodiment, the turbine airfoil 10 may be formed from a generally elongated hollow airfoil 34 formed from an outer wall 32, and having a leading edge 44, a trailing edge 42, a pressure side 46, a suction side 48, and the internal cooling system 14 positioned within interior aspects of the generally elongated hollow airfoil 34 In one embodiment, the turbine airfoil 10 may be a stationary vane, as shown in FIG. 1, such as a turbine vane, with inner and outer endwalls. In another embodiment, the turbine airfoil 10 may be a rotary blade, as shown in FIG. 16, such as a turbine blade As shown in FIGS. 2, 6, 7 and 12, the turbine airfoil 10 may include one or more midchord cooling channels 16 with one or more corrugated inserts 18 positioned therein and creating a leading edge nearwall cooling channel 20 between the leading edge 44 and the corrugated insert 18, a suction side nearwall cooling channel 24 between the suction side 48 and the corrugated insert 18 and a pressure side nearwall cooling channel 22 between the pressure side 46 and the corrugated insert 18. The corrugated insert 18 may be formed from a wall 26 that oscillates in a repeating pattern between peaks 28 and valleys 30, such that the peaks 28 are closer to an inner surface 50 of the outer wall 32 forming the generally elongated hollow airfoil 34. In at feast one embodiment, the peaks 28 and valleys 30 may be generally curved. Portions of the corrugated insert 18 extending between the peaks 28 and valleys 30 may be generally linear.

The turbine airfoil 10 may also include a plurality of rows 36 of partition walls 38 extending from the inner surface 50 forming the outer wall 32 and into the midchord cooling channel 16 On or more partition walls 38 may include gaps 52 therein. The gaps 52 maybe shorter in length than the individual sections of the partition walls 38. The rows 36 of partition walls 38 may be generally aligned with a direction 54 of cooling fluid flow from the leading edge 44 chordwise toward the trailing edge 42. In at least one embodiment, the partition walls 38 may be orthogonal with the leading edge 44 In at least one embodiment, the partition walls 38 may be orthogonal with the leading edge 44 or the trailing edge 42, or both At least a portion of the peaks 28 in the corrugated insert 18 extending radially outward may be aligned with the gaps 52 within at least a portion of at least one partition wall 38 Such alignment of the gaps 52 with the peaks 28 creates periodic impingement upon the impingement surfaces 40 and partial lateral, spanwise movement and mixing of the cooling fluids In particular, the corrugated insert 18 functions in concert with the rows 36 of partition walls 38 to create periodic impingement on the corrugated insert 18, specifically on those surfaces 40 leading from the valleys 30 to the peaks 28 moving toward the trailing edge 42.

As shown in FIGS. 2, 5 and 9-11, the plurality of rows 36 of partition walls 38 may extend from the inner surface 50 into the pressure side nearwall cooling channel 22 Similarly, the plurality of rows 36 of partition walls 38 may extend from the inner surface 50 into the suction side nearwall cooling channel 24 The rows of partition walls 38 may extend in a direction from the leading edge 44 chordwise toward the trailing edge 42. As shown in FIGS. 2 and 12, the leading edge nearwall cooling channel 20 may not include partition walls 38 or other components. In another embodiment, the leading edge nearwall cooling channel 20 may include partition walls 38 or other impingement components One or more inlets 56 may be positioned in the corrugated insert 18 at the leading edge nearwall cooling channel 20 to pass cooling fluid from interior aspects of the corrugated insert 18 to the leading edge nearwall cooling channel 20 The inlets 56 may function as an impingement holes as the compressed air flows from inner aspects of the corrugated insert 18 through the inlets 56 and impinges on a backside, inner surface of the outer wall 32 forming the leading edge 44

In at least one embodiment, as shown in FIGS. 5-10 and 15, the partition wall gaps 52 may extend for a partial length or an entire length of the partition wall 38. One or more of the partition walls 38 may be linear. In at least one embodiment, each of the partition walls 38 may be linear and each of the partition walls 38 may be parallel with each other. The partition walls 38 may have a cross-sectional area with one or more of the following shapes: square, rectangular and trapezoidal, or other appropriate shape.

In another embodiment, as shown in FIG. 15, one or more partition walls 38 may be formed from first and second subpartition walls 58, 60. The second subpartition wall 60 may be offset laterally from first subpartition wall 58, and the first and second subpartition walls 58, 60 may be staggered in an alternating manner moving in a direction from the leading edge 44 toward the trailing edge 42. In another embodiment, each partition wall 38 may be formed from the first and second subpartition walls 58, 60 with the same configuration set forth immediately above Adjacent partition walls 38 may be spaced from each other equidistant, randomly, in a pattern or in another manner. In at least one embodiment, a second subpartition wall 60 may be positioned along an axis 62 that is equidistant from the first subpartition wall 58 within a same partition wall 64 as the second subpartition wall 60 and a first subpartition wall 58 within an adjacent partition wall 66.

The cooling system 14 may also include one or more miniribs 68, as shown in FIGS. 3, 5, 9-11, 13 and 15, extending from the inner surface 50 forming the outer wall 32 and extending between adjacent partition walls 38. The miniribs 68 may be nonparallel with the partition walls 38 and may be shorter in height extending from the inner surface 50 than adjacent partition ribs 38 The miniribs 68 may have a cross-sectional area with one or more of the following shapes: square, rectangular, and trapezoidal, or other appropriate shape. A cross-sectional area of a minirib 68 may be less than a cross-sectional area of the partition wall 38. In at least one embodiment, the cross-sectional area of a minirib 68 may be less than one quarter of the cross-sectional area of the partition wall 38. In yet another embodiment, the cross-sectional area of a minirib 68 may be less than one eight of the cross-sectional area of the partition wall 38 The plurality of miniribs 68 may be aligned with each other and may be orthogonal to the adjacent partition walls 38 The miniribs 68 may extend from a partition wall 38 to an adjacent partition wall 38. In another embodiment, neither end of the miniribs 68 contacts the partition walls 38, as shown in FIGS. 5 and 15 In at least one embodiment, a plurality of miniribs 68 may extend between each adjacent partition walls 38 between gaps 52 In at least one embodiment, at least four miniribs 68 extend between adjacent partition walls 38 between gaps 52. In addition, there may exist one or more miniribs 68 positioned within a gap 52 between two portions of a partition wall 38 within a single partition wall 38

The cooling system 14 may also include one or more trailing edge cooling channels 70, as shown in FIGS. 4 and 14, positioned between the midchord cooling channel 16 and the trailing edge 42 of the generally elongated hollow airfoil 34. The trailing edge cooling channel 70 may include a plurality of pin fins 72 extending from the outer wall 32 forming the pressure side 46 to the suction side 48 and forming zigzag cooling flow channels 74 within the trailing edge cooling channel 70 At least a portion of the pin fins 72 may have cross-sectional areas with a leading edge 76 and a trailing edge 78 that is positioned on a downstream corner 80 and separated from the leading edge 76 by a concave side surface 82 and a convex side surface 84 on an opposite side of the pin fin 72 from the concave side 82. One or more of the zigzag cooling flow channels 74 may be formed from a plurality of pin fins 72 aligned such that the concave and convex side surfaces 82, 84 alternate moving towards the trailing edge 42 As shown in FIGS. 4 and 14, a first upstream pin fin 86 may have a cross-sectional area formed from an upstream section 88 and a downstream section 90. The upstream section 88 may be generally linear with a constant width, and the downstream section 90 may be generally linear with a tapered width that reduces in width moving towards the trailing edge 42 The upstream and downstream sections 88, 90 may be nonlinear and nonorthogonal with each other.

During use, cooling fluids may be supplied from a compressor or other such source to the inner aspect of the corrugated insert 18 of the internal cooling system 14. Cooling fluids are passed through the inlets 56 into the leading edge nearwall cooling channel 20 where the fluids separate with a portion flowing into the pressure side nearwall cooling channel 22 and a portion flowing into the suction side nearwall cooling channel 24. The peaks 28 and valleys 30 of the corrugated insert 18 create periodic impingement on the inner surface 50 of the outer wall 32. The partition walls 38 also direct the cooling fluids towards the trailing edge 42, and in at least some embodiments, create a nonlinear flow path toward the trailing edge to increase convection of heat from the outer wall to the cooling fluid. The cooling fluid may be exhausted through film cooling holes 92 at downstream ends of the pressure and suction side nearwall cooling channels 22, 24.

Cooling fluids may also be passed to the trailing edge cooling channel 70 via one or more trailing edge supply channels 94. The cooling fluids may be metered through metering holes 96 into the trailing edge cooling channel 70. The cooling fluids may flow into the zigzag cooling flow channels 74 where the pin fins 72 direct the cooling fluids in a nonlinear, back and forth motion to the trailing edge 42, where the cooling fluids are exhausted. The cooling fluids in the trailing edge cooling channel 70 receive heat from the outer wall 32 forming the pressure and suction sides 46, 48 and from the pin fins 72

The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of this invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of this invention.