WO2015156816A1

WO2015156816A1 - Turbine airfoil with an internal cooling system having turbulators with anti-vortex ribs

Info

Publication number: WO2015156816A1
Application number: PCT/US2014/033741
Authority: WO
Inventors: Matthew J. GOLSEN; Jose L. Rodriguez
Original assignee: Siemens AG; Siemens Corp; Siemens Energy Inc
Current assignee: Siemens AG; Siemens Corp; Siemens Energy Inc
Priority date: 2014-04-11
Filing date: 2014-04-11
Publication date: 2015-10-15
Anticipated expiration: 2016-10-11

Abstract

A turbine airfoil usable in a turbine engine and having at least one cooling system with one or more turbulators having one or more downstream anti-vortex ribs is disclosed. At least a portion of the cooling system may include one or more cooling channels having one or more turbulators protruding from an inner surface forming the cooling channel. The turbulator may have improved operating characteristics including enhanced heat transfer capabilities and a substantial reduction in pressure drop typically associated with conventional trip strips. In at least one embodiment, one or more anti-vortex ribs may be positioned immediately downstream of the turbulator with descending heights moving downstream. The anti-vortex ribs may be positioned relative to the turbulator and to each other to increase the efficiency of the cooling system by increasing the heat transfer or reducing the pressure drop, or both.

Description

TURBINE AIRFOIL WITH AN INTERNAL COOLING SYSTEM HAVING TURBULATORS WITH ANTI-VORTEX RIBS

FIELD OF THE INVENTION

This invention is directed generally to turbine airfoils, and more particularly to hollow turbine airfoils having cooling channels for passing fluids, such as air, to cool the airfoils.

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 these high

temperatures. As a result, turbine vanes and blades must be made of materials capable of withstanding such high temperatures. In addition, turbine vanes and blades often contain cooling systems for prolonging the life of the vanes and blades and reducing the likelihood of failure as a result of excessive temperatures.

Typically, turbine blades are formed from an elongated portion forming a blade having one end configured to be coupled to a turbine blade carrier and an opposite end configured to form a blade tip. The blade is ordinarily composed of a leading edge, a trailing edge, a suction side, and a pressure side. The inner aspects of most turbine blades typically contain an intricate maze of cooling circuits forming a cooling system. The cooling circuits in the blades receive air from the compressor of the turbine engine and pass the air through the ends of the blade adapted to be coupled to the blade carrier. The cooling circuits often include multiple flow paths that are designed to maintain all aspects of the turbine blade at a relatively uniform temperature. At least some of the air passing through these cooling circuits is exhausted through orifices in the leading edge, trailing edge, suction side, and pressure side of the blade. Cooling fluids pass over trip strips, which increase the heat transfer of the cooling system. While advances have been made in the cooling systems in turbine blades, a need still exists for a turbine blade having increased cooling efficiency for dissipating heat and passing a sufficient amount of cooling air through the blade with as little pressure loss as possible.

SUMMARY OF THE INVENTION

A turbine airfoil usable in a turbine engine and having at least one cooling system with one or more turbulators having one or more downstream anti-vortex ribs is disclosed. At least a portion of the cooling system may include one or more cooling channels having one or more turbulators protruding from an inner surface forming the cooling channel. The turbulator may have improved operating

characteristics including enhanced heat transfer capabilities and a substantial reduction in pressure drop typically associated with conventional trip strips. In at least one embodiment, one or more anti-vortex ribs may be positioned immediately downstream of the turbulator with descending heights moving downstream. The anti-vortex ribs may be positioned relative to the turbulator and to each other to increase the efficiency of the cooling system by increasing the heat transfer or reducing the pressure drop, or both.

In at least one embodiment, 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, a root at a first end of the airfoil and a tip at a second end opposite to the first end, and a cooling system positioned within interior aspects of the generally elongated hollow airfoil. One or more turbulators may protrude from an inner surface defining a cooling channel of the cooling system, wherein the turbulator protrudes inwardly into the channel. One or more anti-vortex ribs may be positioned downstream from the turbulator, whereby a height of the anti- vortex rib may be less than the turbulator and at least one anti-vortex rib may be positioned within a distance downstream of the anti-vortex rib equal to six times a height of the turbulator.

In at least one embodiment, the turbulator may have a cross-sectional shape with a distance between a tip and a base of the turbulator being at least two times larger than a distance between an upstream side and a downstream side of the turbulator. An outer tip of the turbulator may be orthogonal to an upstream side of the at least one turbulator. In at least one embodiment, the turbulator may be positioned nonorthogonal and nonparallel to a longitudinal axis of the cooling channel in which the turbulator resides. As such, the turbulator may be positioned at an angle of between 30 degrees and about 60 degrees relative to a longitudinal axis of the cooling channel. In at least one embodiment, the turbulator may be positioned at an angle of about 45 degrees relative to a longitudinal axis of the cooling channel.

In at least one embodiment, the anti-vortex rib may be aligned with the turbulator. The anti-vortex rib may have a cross-sectional shape with a distance between a tip and a base of the anti-vortex rib being at least two times larger than a distance between an upstream side and a downstream side of the anti-vortex rib. Downstream spacing of the anti-vortex rib from the turbulator may be less than a height of the anti-vortex rib closest to the turbulator. An outer tip of the anti-vortex rib may be orthogonal to an upstream side of the anti-vortex rib. In another

embodiment, the outer tip of the anti-vortex rib may be nonorthogonal to an upstream side of the anti-vortex rib such that a leading edge corner is positioned farther from the inner surface defining the cooling channel of the cooling system than a trailing edge corner. In at least one embodiment, a thickness of the anti-vortex rib between an upstream side and a downstream side of the anti-vortex rib may be less than one half of a thickness of the turbulator between an upstream side and a downstream side of the turbulator. In another embodiment, a thickness of the anti- vortex rib between an upstream side and a downstream side of the anti-vortex rib may be less than one eighth of a thickness of the turbulator between an upstream side and a downstream side of the turbulator.

In at least one embodiment, the cooling system may include a plurality of anti- vortex ribs, whereby a height of each anti-vortex rib decreases moving downstream from the at least one turbulator. Each of the plurality of anti-vortex ribs may be aligned with the at least one turbulator. Each of the plurality of anti-vortex ribs may have a cross-sectional shape with a distance between each tip and each base of each anti-vortex rib being at least two times larger than a distance between an upstream side and a downstream side of each anti-vortex rib. In at least one embodiment, the plurality of anti-vortex ribs may be formed from two anti-vortex ribs. In at least one embodiment, a distance between a first downstream anti-vortex rib and the turbulator may be less than a distance between a second downstream anti- vortex rib and the first downstream anti-vortex rib.

During use, cooling fluid is passed into the cooling system, including the cooling channel. At least a portion of the cooling fluid contacts the turbulator. In particular, at least a portion of the cooling fluid contacts the upstream side of the turbulator. The cooling fluid passes the tip of the turbulator and flows downstream of the turbulator. The presence of one or more anti-vortex ribs substantially disrupts formation of one or more vortices downstream of the turbulator. The flow of cooling fluids downstream of the turbulator substantially with limited formation of vortices, which increases heat transfer and reducing the pressure drop and therefore positively affecting the heat transfer efficiency of the turbulator. This uniquely shaped turbulator and downstream anti-vortex ribs create higher internal convective cooling potential for the turbine blade cooling channel, thus generating a high rate of internal convective heat transfer and efficient overall cooling system performance. This performance equates to a reduction in cooling demand and better turbine engine performance.

An advantage of the turbine airfoil cooling system is that the system is configured to reduce heat within cooling channels and because of its configuration is particularly well suited to reduce heat within cooling channels in industrial gas turbine engines.

Another advantage of the cooling system is that the configuration of the cross- sectional area of the turbulator reduces the amount of pressure drop typically associated with turbulators.

Yet another advantage of the cooling system is that the cooling system can reduce the pressure drop by up to 10 percent and increase the total heat transfer by greater than five percent relative to a comparable gas turbine engine cooling system with turbulators but without anti-vortex ribs, as described herein.

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.

Figure 1 is cross-sectional view of a turbine blade usable in a gas turbine engine and including a cooling system with turbulators having anti-vortex ribs.

Figure 2 is a fillet view of the turbine blade showing the cooling system with turbulators having anti-vortex ribs taken at section line 2-2 in Figure 1 .

Figure 3 is a detailed view of the cooling system with turbulators having anti- vortex ribs taken at section line 3-3 in Figure 2.

Figure 4 is a detailed view of an alternative embodiment of the cooling system with turbulators having anti-vortex ribs taken at section line 4-4 in Figure 2.

Figure 5 is a graph of simulations of the cooling system with turbulators having anti-vortex ribs compared with a turbulator without anti-vortex ribs.

DETAILED DESCRIPTION OF THE INVENTION

As shown in Figures 1 -5, a turbine airfoil 12 usable in a turbine engine and having at least one cooling system 16 with one or more turbulators 18 having one or more downstream anti-vortex ribs 20 is disclosed. At least a portion of the cooling system 16 may include one or more cooling channels 22 having one or more turbulators 18 protruding from an inner surface 24 forming the cooling channel 22. The turbulator 18 may have improved operating characteristics including enhanced heat transfer capabilities and a substantial reduction in pressure drop typically associated with conventional trip strips. In at least one embodiment, one or more anti-vortex ribs 20 may be positioned immediately downstream of the turbulator 18 with descending heights moving downstream. The anti-vortex ribs 20 may be positioned relative to the turbulator 18 and to each other to increase the efficiency of the cooling system 16 by increasing the heat transfer or reducing the pressure drop, or both.

In at least one embodiment, as shown in Figure 1 , the turbine airfoil 12 may be formed from a generally elongated hollow airfoil 26 formed from an outer wall 28, and having a leading edge 30, a trailing edge 32, a pressure side 34, a suction side 36, a root 38 at a first end 40 of the airfoil 26 and a tip 42 at a second end 44 opposite to the first end 40, and a cooling system 16, as shown in Figures 2-4, positioned within interior aspects 46 of the generally elongated hollow airfoil 26. The cooling system 16 may include one or more turbulators 18 protruding from the inner surface 24 defining the cooling channel 22 of the cooling system 16, whereby the turbulator 18 may protrude inwardly into the cooling channel 22. An upstream side 56 of the turbulator 18 may be orthogonal and nonorthogonal relative to the inner surface 24. In at least one embodiment, the turbulator 18 may extend from at least a portion of a distance between walls 48 forming the cooling channel 22, as shown in Figure 2. In another embodiment, as shown in other aspects of Figure 2, the turbulator 18 may extend completely across the cooling channel 22 to contact adjacent walls 48. The turbulator 18 may be positioned nonorthogonal and nonparallel to a longitudinal axis 50 of the cooling channel 22 in which the turbulator 18 resides. The turbulator 18 may be positioned at an angle of between 30 degrees and about 60 degrees relative to the longitudinal axis 50 of the cooling channel 22. In at least one embodiment, the turbulator 18 may be positioned at an angle of about 45 degrees relative to the longitudinal axis 50 of the cooling channel 22. In another embodiment, the tubulator 18 may be positioned orthogonal to the longitudinal axis 50.

The turbulator 18 may have a cross-sectional shape with a distance between a tip 52 and a base 54 of the turbulator 18 being larger than a distance between an upstream side 56 and a downstream side 58 of the turbulator 18. As such, the turbulator 18 may have a generally rectangular cross-sectional shape. In other embodiments, the turbulator 18 may have other cross-sectional shapes. In another embodiment, the turbulator 18 may have a cross-sectional shape with a distance between a tip 52 and a base 54 of the turbulator 18 being at least two times larger than a distance between an upstream side 56 and a downstream side 58 of the turbulator 18. In at least one embodiment, the turbulator 18 may have an outer tip 52 with a surface 51 that is orthogonal to an upstream side 56 of the turbulator 18. In other embodiments, the surface 51 of the outer tip 52 may be nonorthogonal to the upstream side 56 of the turbulator 18. The cooling system 16 may also include one or more anti-vortex ribs 20 positioned downstream from the turbulator 18. In at least one embodiment, the cooling system may include a plurality of anti-vortex ribs 20. In yet another embodiment, two anti-vortex ribs 20 may be positioned downstream from the anti- vortex ribs 20 may have cascading heights in a downstream direction from the turbulator 18. As such, a height of the anti-vortex rib 20 may be less than the turbulator 18. The anti-vortex rib 20 may also be positioned within a distance downstream of turbulator 18 equal to six times a height of the turbulator 18. As such, the distance between the turbulator 18 and the anti-vortex rib 20 may be less than the distance downstream of turbulator 18 equal to six times a height of the turbulator 18. The anti-vortex rib 20 may have a cross-section with a rectangular shape or any other appropriate shape.

In at least one embodiment, the anti-vortex rib 20 may have a cross-sectional shape with a distance between a tip 60 and a base 62 of the anti-vortex rib 20 being larger than a distance between an upstream side 64 and a downstream side 66 of the anti-vortex rib 20. As such, the anti-vortex rib 20 may have a generally rectangular cross-sectional shape. In other embodiments, the anti-vortex rib 20 may have other cross-sectional shapes. In at least one embodiment, the anti-vortex rib 20 may have a cross-sectional shape with a distance between a tip 60 and a base 62 of the anti-vortex rib 20 being at least two times larger than a distance between an upstream side 64 and a downstream side 66 of the anti-vortex rib 20.

Additionally, the anti-vortex rib 20 may be smaller than the turbulator 18 immediately upstream from the anti-vortex rib 20. For example, a thickness of the anti-vortex rib 20 between an upstream side 64 and a downstream side 68 may be less than one half of a thickness of the turbulator 18 between an upstream side 56 and a downstream side 58 of the turbulator 18. In yet another embodiment, the thickness of the anti-vortex rib 20 between an upstream side 64 and a downstream side 66 may be less than one eighth of a thickness of the turbulator 18 between an upstream side 56 and a downstream side 58 of the turbulator 18.

In at least one embodiment, one or more of the anti-vortex ribs 20 may be aligned with the turbulator 18 immediately upstream from the anti-vortex rib 20. In yet another embodiment, each of the anti-vortex ribs 20 may be aligned with the turbulator 18 immediately upstream from the anti-vortex rib 20. The downstream spacing of an anti-vortex rib 20 from the turbulator 18 may be less than a height of the anti-vortex rib 20 closest to the turbulator 18. In at least one embodiment, the distance between adjacent anti-vortex ribs 20 or between an anti-vortex rib 20 and the turbulator 18 may be equal. In other embodiments, the distance between adjacent anti-vortex ribs 20 or between an anti-vortex rib 20 and the turbulator 18 may be different. In particular, a distance between a first downstream anti-vortex rib 68 and the turbulator 18 may be less than a distance between a second downstream anti-vortex rib 70 and the first downstream anti-vortex rib 68.

In at least one embodiment, as shown in Figure 3, a surface 61 of an outer tip

60 of the anti-vortex rib 20 may be orthogonal to an upstream side 64 of the anti- vortex rib 20. In another embodiment, the surface 61 of the outer tip 60 of the anti- vortex rib 20 may be orthogonal to the inner surface 24 forming the cooling channel 22. In yet another embodiment, the surface 61 of the outer tip 60 of the anti-vortex rib 20 may be nonorthogonal to the upstream side 64 of the anti-vortex rib 20 such that a leading edge corner 72 is positioned farther from the inner surface 24 defining the cooling channel 22 of the cooling system 16 than a trailing edge corner 74, as shown in Figure 4.

In at least one embodiment, a turbulator 18 may have a plurality of anti-vortex ribs 20 positioned downstream of the turbulator 18, whereby a height of each anti- vortex rib 20 decreases moving downstream from the turbulator 18. In such embodiment, one or more, and in at least one embodiment, each of the plurality of anti-vortex ribs 20 may be aligned with the turbulator 18. One or more, and in at least one embodiment, each of the plurality of anti-vortex ribs 20 may have rectangular cross-sectional areas. For example, one or more, and in at least one embodiment, each of the plurality of anti-vortex ribs 20 may have a cross-sectional shape with a distance between each tip 52 and each base 54 of each anti-vortex rib 20 being at least two times larger than a distance between an upstream side 64 and a downstream side 66 of each anti-vortex rib 20. In at least one embodiment, the plurality of anti-vortex ribs 20 may be two anti-vortex ribs 20 position downstream from a turbulator 18. During use, cooling fluid is passed into the cooling system 16, including the cooling channel 22. At least a portion of the cooling fluid contacts the turbulator 18. In particular, at least a portion of the cooling fluid contacts the upstream side 56 of the turbulator 18. The cooling fluid passes the tip 52 of the turbulator 18 and flows downstream of the turbulator 18. The presence of one or more anti-vortex ribs 20 substantially disrupts formation of vortices downstream of the turbulator 18. The flow of cooling fluids downstream of the turbulator 18 substantially without formation of any vortices increases heat transfer and reduces the pressure drop. This uniquely shaped turbulator 18 and downstream anti-vortex ribs 20 create higher internal convective cooling potential for the turbine blade cooling channel 22, thus generating a high rate of internal convective heat transfer and efficient overall cooling system performance, as shown in Figure 5. This performance equates to a reduction in cooling demand and better turbine engine performance.

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.

Claims

CLAIMS I 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, a root at a first end of the airfoil and a tip at a second end opposite to the first end, and a cooling system positioned within interior aspects of the generally elongated hollow airfoil;

at least one turbulator protruding from an inner surface defining a cooling channel of the cooling system, wherein the at least one turbulator protrudes inwardly into the channel; and

at least one anti-vortex rib positioned downstream from the at least one turbulator, whereby a height of the at least one anti-vortex rib is less than the at least one turbulator and wherein the at least one anti-vortex rib is within a distance downstream of the at least one anti-vortex rib equal to six times a height of the at least one turbulator.

2. The turbine airfoil of claim 1 , wherein the at least one turbulator has a cross-sectional shape with a distance between a tip and a base of the at least one turbulator being at least two times larger than a distance between an upstream side and a downstream side of the at least one turbulator.

3. The turbine airfoil of claim 1 , wherein a surface of an outer tip of the at least one turbulator is orthogonal to an upstream side of the at least one turbulator.

4. The turbine airfoil of claim 1 , wherein the at least one turbulator is positioned nonorthogonal and nonparallel to a longitudinal axis of the cooling channel in which the at least one turbulator resides.

5. The turbine airfoil of claim 1 , wherein the at least one turbulator is positioned at an angle of between 30 degrees and about 60 degrees relative to a longitudinal axis of the cooling channel.

6. The turbine airfoil of claim 1 , wherein the at least one anti-vortex rib is aligned with the at least one turbulator.

7. The turbine airfoil of claim 1 , wherein the at least one anti-vortex rib has a cross-sectional shape with a distance between a tip and a base of the at least one anti-vortex rib being at least two times larger than a distance between an upstream side and a downstream side of the at least one anti-vortex rib.

8. The turbine airfoil of claim 1 , wherein a surface of an outer tip of the at least one anti-vortex rib is orthogonal to an upstream side of the at least one anti- vortex rib.

9. The turbine airfoil of claim 1 , wherein a surface of an outer tip of the at least one anti-vortex rib is nonorthogonal to an upstream side of the at least one anti- vortex rib such that a leading edge corner is positioned farther from the inner surface defining the cooling channel of the cooling system.

10. The turbine airfoil of claim 1 , wherein a thickness of the at least one anti-vortex rib between an upstream side and a downstream side is less than one half of a thickness of the at least one turbulator between an upstream side and a downstream side.

1 1 . The turbine airfoil of claim 1 , wherein a thickness of the at least one anti-vortex rib between an upstream side and a downstream side is less than one eighth of a thickness of the at least one turbulator between an upstream side and a downstream side.

12. The turbine airfoil of claim 1 , wherein the at least one anti-vortex rib comprises a plurality of anti-vortex ribs, whereby a height of each anti-vortex rib decreases moving downstream from the at least one turbulator.

13. The turbine airfoil of claim 12, wherein each of the plurality of anti- vortex ribs is aligned with the at least one turbulator.

14. The turbine airfoil of claim 12, wherein each of the plurality of anti- vortex ribs has a cross-sectional shape with a distance between each tip and each base of each anti-vortex rib being at least two times larger than a distance between an upstream side and a downstream side of each anti-vortex rib.

15. The turbine airfoil of claim 12, wherein a distance between a first downstream anti-vortex rib and the at least one turbulator is less than a distance between a second downstream anti-vortex rib and the first downstream anti-vortex rib.

16. A turbine airfoil, comprising:

at least one turbulator protruding from an inner surface defining a cooling channel of the cooling system, wherein the at least one turbulator protrudes inwardly into the channel;

a plurality of anti-vortex ribs positioned downstream from the at least one turbulator, whereby a height of each anti-vortex rib decreases moving downstream from the at least one turbulator and wherein the plurality of ribs are within a distance downstream of the at least one turbulator equal to six times a height of the at least one turbulator; and

wherein the at least one turbulator has a cross-sectional shape with a distance between a tip and a base of the at least one turbulator being at least two times larger than a distance between an upstream side and a downstream side of the at least one turbulator.

17. The turbine airfoil of claim 16, wherein a surface of an outer tip of the at least one turbulator is orthogonal to an upstream side of the at least one turbulator and wherein the at least one turbulator is positioned nonorthogonal and nonparallel to a longitudinal axis of the cooling channel in which the at least one turbulator resides.

18. The turbine airfoil of claim 16, wherein at least one anti-vortex rib is aligned with the at least one turbulator, and wherein at least one of the plurality of anti-vortex ribs has a cross-sectional shape with a distance between a tip and a base of the plurality of anti-vortex ribs being at least two times larger than a distance between an upstream side and a downstream side of the plurality of anti-vortex ribs.

19. The turbine airfoil of claim 16, wherein a surface of an outer tip of the at least one turbulator is nonorthogonal to an upstream side of the at least one turbulator such that a leading edge corner is positioned farther from the inner surface defining the cooling channel of the cooling system.

20. A turbine airfoil, comprising:

a plurality of anti-vortex ribs positioned downstream from the at least one turbulator, whereby a height of each anti-vortex rib decreases moving downstream from the at least one turbulator and wherein the plurality of ribs are within a distance downstream of the at least one turbulator equal to six times a height of the at least one turbulator;

wherein at least one anti-vortex rib is aligned with the at least one turbulator; wherein at least one of the plurality of anti-vortex ribs has a cross-sectional shape with a distance between a tip and a base of the plurality of anti-vortex ribs being at least two times larger than a distance between an upstream side and a downstream side of the plurality of anti-vortex ribs; and

wherein a thickness of the at least one anti-vortex rib between an upstream side and a downstream side is less than one half of a thickness of the at least one turbulator between an upstream side and a downstream side.