WO2017023327A1

WO2017023327A1 - Trailing edge duct for combustors with cooling features

Info

Publication number: WO2017023327A1
Application number: PCT/US2015/043959
Authority: WO
Inventors: Timothy A. Fox; Brede Kolsrud; Jacob William HARDES
Original assignee: Siemens Aktiengesellschaft; Siemens Energy, Inc.
Priority date: 2015-08-06
Filing date: 2015-08-06
Publication date: 2017-02-09

Abstract

A combustor has a trailing edge duct (110) that has cooling features located at various locations. The cooling features comprise pockets (125) that have pocket channels (127) which extend from the pockets (125) to seam locations on the main duct portion (112). Additional cooling features comprise slots (132) located proximate to the pockets (125) and the trim line (131) at a distal end of the main duct portion (112). In other embodiments, cooling channels (136a, 136b, 136c) are formed on the mating surfaces (135) of the extension flange (115). Further in other embodiments, cooling features may be found in the trailing edge (120) of the trailing edge duct (110).

Description

TRAILING EDGE DUCT FOR COMBUSTORS WITH COOLING FEATURES

BACKGROUND

1. Field [0001] Disclosed embodiments are generally related to gas turbine combustors and, more particularly to the structure of cooling components for the combustors.

2. Description of the Related Art [0002] Previously annular gas turbine engines included several individual combustor cans disposed radially outside of and axially aligned with a rotor shaft. Combustion gases produced in these combustor cans were guided radially inward and then transitioned to axial movement by a transition duct. Turning vanes then received the combustion gases, accelerated the gases and directed the gases for delivery into a first stage of turbine blades .

[0003] In these gas turbine combustors an integrated exit piece (IEP) design had been used. In the IEP design, the transition ducts would merge to form a converging flow junction (CFJ). Fig. 1 shows a CFJ transition duct 10 that had been used to form the CFJ junction. The CFJ transition duct 10 has a primary opening 1 1 located at the main casting duct portion 12 and a secondary opening 17 located at the top sheet duct portion 14. The CFJ transition duct 10 was constructed by being cast as a unitary piece. Additionally shown in Fig. 1 is the flange 16 and circular flange 19 which have bolt holes 13 formed therein. The bolt holes 13 are used to interconnect the IEPs of the combustors.

[0004] CFJ transition duct 10 has been cooled via a pattern of ribs 18 supported on the outside surface of the main casting duct portion 12 and the top sheet duct portion 14. The manner in which the ribs 18 cooled the CFJ transition duct 10 created stress challenges in the connection between the main casting duct portion 12 and the top sheet duct portion 14. Furthermore, high stresses would occur at the central notch 15. [0005] The stress challenges created by the geometry of the CFJ duct 10 and the manner in which the CFJ transition ducts 10 were connected resulted in limitations with respect to the structural integrity of the ducts themselves and the connection of the main casting duct portions 12 around the gas turbine engines.

[0006] To overcome this problem trailing edge ducts were developed. However, in order to maximize the efficacy of the trailing edge ducts at several locations, additional cooling approaches may be needed. SUMMARY

[0007] Briefly described, aspects of the present disclosure relate to trailing edge ducts used with gas turbine combustors.

[0008] An aspect of the disclosure is a trailing edge duct having a main duct portion. The trailing edge duct also has an extension flange connected to the main duct portion, wherein the main duct portion and the extension flange form a trailing edge wherein the main duct portion further comprises a surface, wherein the surface comprises a plurality of pockets formed therein. Also the main duct portion further comprises a cooling feature formed proximate to at least one of the pockets.

[0009] Another aspect of the disclosure is a trailing edge duct having a main duct portion. The trailing edge duct also has an extension flange connected to the main duct portion, wherein the main duct portion and the extension flange form a trailing edge; wherein the extension flange has a first open face portion, wherein the first open face portion has cooling channels formed therein that are adapted to be mated with a second open face portion located on another trailing edge duct. [0010] Still yet another aspect of the disclosure is a trailing edge duct having a main duct portion, an extension flange connected to the main duct portion, wherein the main duct portion and the extension flange form a trailing edge; and wherein the trailing edge has a plurality of film channels formed therein. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 shows a prior art view of a converging flow junction transition duct.

[0012] Fig. 2 shows a trailing edge duct.

[0013] Fig. 3A shows a view of a surface of a trailing edge duct with pockets having an intersecting seam.

[0014] Fig. 3B shows a view of a surface of the trailing edge duct with pockets having a pocket channel.

[0015] Fig. 4A shows a view of a surface of the trailing edge duct at a trim line.

[0016] FIG. 4B shows a view of a surface of the trailing edge duct at the trim line with pockets proximate to the trim line removed.

[0017] Fig. 4C shows a view of a surface of the trailing edge duct at the trim line with slots.

[0018] Fig. 4D shows top down and side views of slots.

[0019] Fig. 5 is a view of the extension flange.

[0020] Fig. 6A shows an embodiment of a cooling channel placed on a trailing edge.

[0021] Fig. 6B shows another embodiment of a cooling channel placed on a trailing edge.

[0022] Fig. 6C shows yet another embodiment of a cooling channel placed on a trailing edge.

[0023] Fig. 6D shows another embodiment of a cooling channel placed on a trailing edge.

[0024] Fig. 7 shows a top down view of a trailing edge.

[0025] Fig. 8 shows a cross-sectional view of a trailing edge taken along the line Vm-Vm in Fig. 7. [0026] Fig. 9 shows a view of fluid channels and film channels having connecting regions.

DETAILED DESCRIPTION

[0027] To facilitate an understanding of embodiments, principles, and features of the present disclosure, they are explained hereinafter with reference to implementation in illustrative embodiments. Embodiments of the present disclosure, however, are not limited to use in the described systems or methods.

[0028] The components and materials described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable components and materials that would perform the same or a similar function as the materials described herein are intended to be embraced within the scope of embodiments of the present disclosure.

[0029] Fig. 2 shows a trailing edge duct 110 in which aspects of the present invention can be employed. The trailing edge duct 110 has a main duct portion 1 12 having a primary opening 1 11 and secondary opening 117. The main duct portion 112 may be formed of more than one panel, for example the main duct portion 112 shown in Fig. 2 is formed from a first main panel portion 121 and a second main panel portion 122 that are joined at a seam 123 via welding. The primary opening 11 1 receives fluids during operation in gas turbine engines. Located at and surrounding the primary opening 1 1 1 is an annular flange 119 having through holes 109 located therein. Located at the secondary opening 117 is an extension flange 115, which is discussed in more detail below. The extension flange 1 15 and the main duct portion 112 together form the trailing edge 120 of the trailing edge duct 1 10. [0030] Typically, in an under cooled area on a channel cooled transition, the most common fix is to add effusion holes. Effusion holes consume a lot of air and are relatively inefficient by themselves in the compound angle transition context, as the high pressure drop causes them to consume unreasonably large amounts of flow. [0031] Conventional cooling features consume too much air and do not use that air efficiently in the trailing edge duct 1 10 or other compound angle transition environments.

[0032] Trailing edge duct 1 10 uses pockets 125, shown in Fig. 3A, to provide cooling. Ribs 124 surround the the pockets 125 and provide structural support. The pockets 125 cool the trailing edge duct 1 10 by entering through a hole (not shown) in the outer surface of the trailing edge duct 110. The air then circulates throughout the pocket 125. The ribs 124 do not benefit from the cooling air and preferably have a uniform thickness throughout the trailing edge duct 110.

[0033] The pockets 125 are hexagonal in shape and form a depression in the surface of the main duct portion 112. While the pockets 125 are preferably hexagonal in shape, it is contemplated that other shapes may be utilized, for example pockets 125 may be circular, pentagonal, square, triangle, heptagonal, octagonal, or some other polygonal shape. With respect to the pockets 125, their ability to be located proximate to each other (or nest closely together) with uniform thicknesses of the ribs 124 favors a pocket 125 that is hexagonal shaped. Also, hexagonal shaped pockets 125 assist in making the stiffness uniform so as to withstand forming operations. Alternatively, square or triangle shaped pockets 125 can also be located proximate to each other.

[0034] In an embodiment of the disclosure the pockets 125 are modified to implement an additional cooling feature once the location of the seam 123 on the main duct portion 112 is determined. Fig. 3 A illustrates how a seam 123 impacts a uniform distribution of pockets 125. In this instance the uniform distribution of pockets 125 are hexagonal. The seam 123 is formed across and intersects the pockets 125 at various locations on both the first main panel portion 121 and the second main panel portion 122. The intersection of the pockets 125 reduces the effectiveness of the pockets 125 in providing adequate cooling.

[0035] Fig. 3B shows how the pockets 125 are modified. The portion of the pocket 125 located proximate to the seam 123 forms a pocket channel 127 that is extended to the seam 123. The pocket channel 127 is formed by pocket channel ribs 128. Pocket channel ribs 128 are preferably linear walls. In the embodiment shown in Fig. 4B, the pocket channel 127 extends linearly at an angle a with respect to the seam 123. Preferably, the angle a is an obtuse angle. However, it is contemplated that the angle a can fall within the range of 90° to 180°. Preferably, pocket channel rib 128 extends within the range 1 10°-165° and more preferably 115° to 155°. In the embodiment shown in Fig. 4B the angle is 120°. Preferably the pocket channel rib 128 extends at an angle that is able to keep the thickness of the pocket channel rib 128 and rib 124 substantially uniform. Fig. 3B shows the pockets 125 modified on the first main panel portion 121, however it should be understood that the same modification is made to the pockets 125 on the second main panel portion 122. [0036] The pocket channel 127 of the pocket 125 in conjunction with the seam 123 serves as a cooling feature. The seam 123 functions as a rib between the pockets 125, for the trailing edge duct 1 10. This means that no additional air is consumed by the seam 123 as the cooling spacing will remain relatively unchanged with respect to the rest of the main duct portion 1 12. The pocket channel 127 used on the main duct portion 112 can improve the cooling ability of the trailing edge duct 110.

[0037] Another aspect of the disclosure is an embodiment which provides slots 132 at a location proximate to the exit, such as secondary opening 1 17, of the trailing edge duct 1 10. Fig. 4A illustrates how the trimming of the main duct portion 112 would impact a uniform distribution of pockets 125. In this instance the uniform distribution of pockets 125 are hexagonal. The trim line 131 is formed across and intersects the pockets 125 at various locations on the first main panel portion 121. The intersection of the pockets 125 reduces the effectiveness of the pockets 125 to provide adequate cooling.

[0038] Fig. 4B illustrates how the pockets 125 located near the trim line 131 are removed from the first main panel portion 121 of the main duct portion 1 12. Pockets 125 are removed so as to eliminate any intersection of the pockets 125 by the trim line 131. Fig. 4C illustrates the addition of the slots 132 that are located proximate to the trim line 131. The trim line 131 is located at a proximate edge of the main duct portion 1 12. The additional slots 132 provide additional cooling under rails located at the exit of the trailing edge duct 110, such as second opening 117. The slots 132 provided at the trim line 131 function in a similar manner as the pocket channels 127 discussed above with respect to the seam 123. However, instead of reshaping the pockets 125, the pockets 125 that would be impacted by the trim line 131 are removed and slots 132 formed in their place. These slots 132 will dump out air axially at the end of the main duct portion 112.

[0039] Referring to Figs. 4C and 4D, slots 132 extend from the trim line 131 to a location proximate to the pocket 125. Each slot 132 may extend a different length from the trim line 131. On average the slot 132 will have a height H and width W that will be on the order of ¼ the thickness of the wall of the of the trailing edge duct 1 10. The width W and height H of the trailing edge duct 110 will be similar. For example the slots 132 shown in Figs 4C and 4D have a height H of 1.6 mm and a width W of 2 mm. The width W determines how many cooling holes will be needed to fill the trailing edge duct 110 with sufficient flow in order to obtain the heat transfer coefficient (HTC) desired. The slots 132 shown in Fig. 4C preferably extend orthogonally with respect to a lengthwise direction of the trim line 131. However, it should be understood that other angles may be possible. Preferably all of the angles should discharge in the same direction as the bulk flow of the trailing edge duct 1 10.

[0040] Each slot 132 will be fed by impingement holes 133 as shown in Fig. 4D. Each slot 132 may be straight, however this may not provide sufficient cooling. Therefore, slot 132 may have "jogs," such as jog 137 shown in Fig. 4D, added to the slot 132 to create a longer overall path for the slots 132. A "jog" is an abrupt change in direction. More jogs 137 can be added if a longer slot 132 is needed that requires a longer path.

[0041] Also disclosed is an embodiment where the surfaces of the trailing edge ducts 1 10 mate together and form cooling features. Referring now to Fig. 5, shown is a front view of an extension flange 115 which is located on a trailing edge duct 110. The extension flange 1 15 is formed so as to conform to the shape of the secondary opening 117. The extension flange 1 15 shown in Fig. 5 is secured to the main duct portion 1 12 by welding. It should be understood that while extension flange 1 15 is shown as being attachable, it may be possible to form the extension flange 115 integrally with the main duct portion 1 12.

[0042] Extension flange 115 has an open face portion 135. Milled onto the surface of the open face portion 135 are portions of what will become enclosed cooling channels 136a, 136b and 136c, shown respectively in Figs. 6A, 6B and 6C. Enclosed cooling channel 136a forms a straight line when viewed in cross-section. However, other shapes are contemplated. For example enclosed cooling channel 136b may form a wave pattern when viewed in cross-section. This wave pattern may be sinusoidal and can provide additional cooling. Additionally, enclosed cooling channel 136c may form a jagged pattern when viewed in cross-section which can provide additional cooling. It is also contemplated that if additional cooling were required, the enclosed cooling channels 136a, 136b and 136c could be extended. However, it should be understood that other shapes may be formed in addition to those shown in the figures. For example, Fig. 6D shows cooling channel 136d, which is formed with jagged contours. The jagged contours may be may be machined in the same manner as those shown in Figs. 6A-6C, or alternatively in the depth of the channels thereby having a channel of variable depth

[0043] Additionally, in some instances there may be a need to maintain film cooling at the trailing edge 120. Fig. 6 shows a top down view of a trailing edge 120. The trailing edge duct 1 10 relies on two basic cooling aspects, impingement cooling in the pockets 125 and film cooling from the discharge air in pockets 125. The trailing edge 120 means the end of the pockets 125, and can create a long section where film is no longer being recharged. However the film can be recharged by using the cooling of the trailing edge 120.

[0044] Referring to Figs. 7 and 8, in an embodiment of the trailing edge duct 1 10, the trailing edge 120 is provided with the ability to feed film holes from film channels 141. Fluid channels 140 and film channels 141 have been designed have a width between 0.5 mm and 2.0 mm. and a depth of between 0.1 mm-1 mm. The width of the fluid channels 140 and the film channels 141 permit conventional machining (milling) of the channels. The length of the fluid channels 140 and film channels 141 may be the length of the trailing edge 120. The vertical pitch, i.e. the distance between the vertical axes of each fluid channel 140 and film channel 141 may be 2.5 mm. However the size and shape of the fluid channels 140 and film channels 141 will depend on the size shape of the trailing edge duct 1 10. Further, it should be understood that other dimensions may be used depending on the cooling needs for the film.

[0045] Fig. 8 shows a side cross-sectional view, taken along line VIII- VIII, in Fig. 7, of a trailing edge 120 having film channels 141 extending at an angle β from the upper perimeter 142 of the trailing edge 120. In Fig. 8 only film channels 141 are shown, fluid channels 140 are not shown. Preferably, the angle β is the same for each of the film channels 141 shown. However, the angles may vary depending on the film cooling that is desired. Angle β may be between 0°-90°, is more preferably between 15°-75° degrees and most preferable between 35°-55°. The film channels 141 shown in Fig. 6 extend at an angle β of 45°.

[0046] The film channels 141 are also tapered. The tapering of the film channel 141 is intended to keep the heat transfer coefficient substantially constant as film air is removed. The tapering of the film channels 141 may be gradual and in the embodiment shown in Figs. 7 and 8, film channels 141 which feed film holes are tapered. The tapering concept is illustrated in Fig. 9 where a top down cross-sectional view of the trailing edge 120 and film channels 141 are shown. In this embodiment there is one film channel 141 for every three fluid channels 140. While the embodiment shown provides one film channel 141 for every three fluid channels 140, other distributions of film channels 141 may be used, such as one film channel 141 for every two fluid channels 140. The film channel 141 has a local increase in size forming connecting region 143.

[0047] In the embodiment shown the connecting region 143 is round. Also there is more than one connecting region 143 per a film channel 141. In the embodiment shown there is at least three connecting regions 143 per a film channel 141. The connecting regions 143 along the film channel 141 allow for machining to be performed from the "hot side" to meet up with the connecting regions 143. A film channel 141 that had, for example four connecting regions 143 and a standard exit would require three to four times the flow of a fluid channel 140 with only a standard exit. For this reason, the depth of a film channel 141 may vary. Preferably, the exit hole at the end of the trailing edge 120 has the same flow rate and temperature of cooling air as its neighbor which might have no connecting regions, and would as a result be of constant depth.

[0048] However it should be understood that the connecting region 143 may be differently shaped, such as having a connecting region 143 that is double the width of the rest of the film channel 141. Alternatively, the connecting region 143 may have a zigzag shape. The connecting region 143 will make an area where a film hole can be connected to the hot side. The film channel 141 may also be tapered to provide an extra flow rate in the film channel 141 prior to the film dumps.

[0049] While embodiments of the present disclosure have been disclosed in exemplary forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents, as set forth in the following claims.

Claims

What is claimed is:

1. A trailing edge duct (110) comprising:

a main duct portion (1 12);

an extension flange (1 15) connected to the main duct portion (112), wherein the main duct portion (1 12) and the extension flange (115) form a trailing edge (120);

wherein the main duct portion (1 12) further comprises a surface, wherein the surface comprises a plurality of pockets (125) formed therein; and wherein the main duct portion (112) further comprises a cooling feature formed proximate to at least one of the pockets (125).

2. The trailing edge duct (1 10) of claim 1, further comprising a seam (123) formed between a first main panel portion (121) and a second main panel portion (122).

3. The trailing edge duct (110) of either claim 1 or 2, wherein a pocket channel (127) extends from the at least one of the pockets (125) to the seam (123).

4. The trailing edge duct (110) of any one of claims 1-3, wherein the pocket channel (127) is formed by linear rib (128) which extend at an angle of between 110°-165° with respect to the seam (123).

5. The trailing edge duct (110) of claim 1, wherein the cooling feature is a slot

(132) that extends orthogonally from a lengthwise direction of a trim line (131).

6. The trailing edge duct (1 10) of either claim 1 or 5, wherein more than one slot (132) extends from the trim line (131).

7. The trailing edge duct (1 10) of any one of claims 1, 5 or 6, wherein at least two slots (132) extend a different distance from the trim line (131).

8. The trailing edge duct (1 10) of any one of claims claim lor 5, wherein the slot (132) has a jog (137).

9. A trailing edge duct (110) comprising:

a main duct portion (1 12);

an extension flange (1 15) connected to the main duct portion (112), wherein the main duct portion (1 12) and the extension flange (115) form a trailing edge (120) ; and

wherein the extension flange (115) has a first open face portion (135), wherein the first open face portion (135) has cooling channels (136a, 136b, 136c) formed therein that are adapted to be mated with a second open face portion located on another trailing edge duct.

10. The trailing edge duct (110) of claim 9, wherein the cooling channel (136a) forms a straight line when viewed in cross-section.

11. The trailing edge duct (110) of claim 9, wherein the cooling channel (136b, 136b) forms a sinusoidal or jagged pattern when viewed in cross-section.

12. The trailing edge duct (1 10)of claim 9, wherein the main duct portion (112) further comprises a surface, wherein the surface comprises a plurality of pockets (125) formed therein; and

wherein the main duct portion (112) further comprises a cooling feature formed proximate to at least one of the pockets (125).

13. The trailing edge duct (110) of claim 9, further comprising a seam (123) formed between a first main panel portion (121) and a second main panel portion (122).

14. The trailing edge duct (110) of claim 9, wherein a pocket channel (125)

extends from the at least one of the pockets (125) to the seam (123).

15. The trailing edge duct (1 10) of claim 9, wherein the pocket channel (125) is formed by linear wall (128) which extend at an angle between 1 10°- 165° with respect to the seam (123).

16. The trailing edge duct (1 10) of claim 9, wherein the cooling feature is a slot (132) that extends orthogonally from a lengthwise direction of a trim line (131).

17. A trailing edge duct (110) comprising:

a main duct portion (1 12);

an extension flange (1 15) connected to the main duct portion (112), wherein the main duct portion (1 12) and the extension flange (115) form a trailing edge (120); and

wherein the trailing edge (120) has a plurality of film channels (141) formed therein.

18. The trailing edge duct (1 10) of claim 17, wherein the film channels (141) extend at an angle of between 35° to 75° from the upper perimeter (142) of the trailing edge (120).

19. The trailing edge duct of claim 17, wherein the film channels (141) have round connecting regions (143) formed therein.

20. The trailing edge duct of claim 17, wherein the trailing edge further comprises a plurality of fluid channels (140), wherein there is one film channel (141) for every three fluid channels (140).