WO2020046376A1

WO2020046376A1 - Transition duct exit frame with impingement cooling

Info

Publication number: WO2020046376A1
Application number: PCT/US2018/049130
Authority: WO
Inventors: Jacob William HARDES
Original assignee: Siemens Aktiengesellschaft; Siemens Energy, Inc.
Priority date: 2018-08-31
Filing date: 2018-08-31
Publication date: 2020-03-05
Also published as: WO2020046376A9

Abstract

A cooling channel arrangement for a turbine engine transition exit frame is de-scribed. The cooling arrangement includes a primary cooling channel in fluid communication with a source of cooling fluid. A turbulent flow chamber in fluid communication with said primary cooling path is sealed by a capping element constructed and arranged to form a fluid tight seal of said disruptive flow chamber. An exit channel is disposed within the cap-ping element, and the turbulent flow chamber and exit channel cooling assembly are adapted to cooperatively provide impingement cooling of said capping element.

Description

TRANSITION DUCT EXIT FRAME WITH IMPINGEMENT COOLING

FIELD OF THE INVENTION

Disclosed embodiments are generally related to cooling channel arrange- ments, and, more particularly, to a cooling channel having features that increase cooling efficiency in a combustion turbine engines.

BACKGROUND OF THE INVENTION

In a combustion turbine engine, such as a gas turbine engine, combustion chambers combust fuel mixed with compressed air, and a hot working gas flowing from these combustion chambers is passed via respective transitions to respective entrances of the turbine, where energy in the working gas flow is converted into rotational energy. Often this rotational energy is used to generate electricity by coupling the turbine shaft with a generator (not shown).

Many of the components along the path taken by the hot working gas must be cooled to accommodate operation at the elevated temperatures desired to maximize the energy released from the fuel and carried by the hot working gas as it flows toward the exit of the engine. Combustor-to-turbine transitions section, for example, are exposed to extremely-high temperatures during engine operation.

To avoid transition failure, temperatures in the hottest areas of the compo- nents, such as the transition exit frames, are kept at or just below allowable maxi- mums, with resulting temperatures in cooler regions being well-below component maximums and cooler regions being overcooled. Modern engine transitions are often sheet metal fabrications, with exit frame sections and associated cooling channels manufactured through electrical discharge machining (EDM), milling, or similar subtractive manufacturing processes. As a result, known transition cooling arrangements often rely on an array of relatively-straight cooling channels to trans- fer cooing fluid through the exit frame to keep temperatures below component maximums during operation. Unfortunately, cooling fluid heats up as it travels along these“Nne-of-sight” style cooling passageways and these cooling approach- es result in from poor cooling performance at the frame exit - the hottest section of the turbine frame. While it is possible to maintain desired temperatures, using straight-through cooling channels produced by known drilling methods their use, as noted above, is inefficient, wasting precious cooling fluid and reducing the effi- ciency and overall performance of the engine.

What is needed is a cooling arrangement that provides efficient cooling in non-cast components, such as transition exit frames, with high-temperature re- gions formed via milling, EDM, or other subtractive manufacturing process.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in the following description in view of the draw- ings that show:

FIG. 1 is a simplified schematic of one non-limiting embodiment of a com- bustion turbine engine that can benefit from aspects of the present invention.

FIG. 2 is a cutaway view of a transition exit frame illustrating one embodi- ment of the present cooling arrangement.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a simplified schematic of one non-limiting embodiment of a com- bustion turbine engine 10, such as gas turbine engine, that can benefit from as- pects of the present invention. Combustion turbine engine 10 comprises a com- pressor 12, a combustor 14, a combustion chamber 16 (such as a can-annular type), and a turbine 18. During operation, compressor 12 takes in ambient air and provides compressed air to a diffuser 20, which passes the compressed air to a plenum 22 through which the compressed air passes to combustor 14, which mix- es the compressed air with fuel, and provides combusted, hot working gas via a transition 24 to turbine 18, which can drive power-generating equipment (not shown) to generate electricity.

With reference to FIG. 2, the cooling arrangement 27 of the present inven- tion addresses certain issues arising in connection with typical EDM-generated cooling flow channels 28,30 and improves on the known arrangement by introduc- ing two additional elements that increase the cooling efficiency within a transition exit frame: a turbulent flow chamber 32 and an offset exit channel 36. The turbu- lent flow chamber 32 and offset exit channel cooperatively bring enhanced cooling to the turbine-facing end of the by disrupting the flow path of coolant flowing through the exit frame 26, creating turbulent flow that beneficially increases the amount of heat removed in the flow-wise downstream end region 38.

By way of overview and with continued reference to FIG. 2, the present cooling arrangement includes a first cooling channel 28, a downstream second cooling channel, and a turbulent flow chamber 32 adjoining the second cooling channel. The turbulent flow chamber 32 is bounded by a downstream sealing cap 34 characterized by an offset exit channel 36 that allows cooling fluid to leave the transition exit frame end region 38 after repeatedly striking the chamber cap 34 before finding - and then passing through - the offset exit channel 36. This bene- ficially provides an impingement cooling effect to the end region 38 of the transi- tion exit frame 26. The exit channel 36 may be offset from the second cooling channel 30 in several ways. For example, the exit channel 36 may be radially off- set from the second cooling channel 30. Flowever, the exit channel 36 may also be circumferentially offset from the second cooling channel 30. The exit channel 36 may even be offset in both the radial and circumferential directions.

The first and second cooling channels 28,30 are typically formed via an EDM process, with the first cooling channel 28 intersecting, and angled with re- spect to, the second cooling channel 30. The turbulent flow chamber 32 may be formed from any number of subtractive manufacturing operations, including but not limited to machining, and a boundary cap 34 seals the chamber, except for the exit channel 36 that provides a path for cooling fluid to leave the chamber.

With this arrangement, the cooling channels 28,30 provide a path for cool- ing fluid to move through a downstream end region 38 of the transition exit frame 26. During operation, cooling fluid (not shown) moves through the first and second cooling channels 28,30 until exiting the second channel and gathering in the turbu- lent flow chamber 32, where flow of the cooling fluid will be disrupted as it repeat- edly strikes (and provides impingement cooling to) the downstream chamber boundary cap 34. Eventually, the cooling fluid enters the exit channel 36 disposed in the cap 34 and travels out of the transition exit frame 26.

The present cooling arrangement 27 may advantageously be manufactured in a series of steps. First, a transition exit frame 26 (such as one formed as per typical subtractive fabrication methods) is obtained. Second, a first cooling channel 28 is formed (such as by drilling or EDM) within an end region of the exit frame; the first channel has an entrance 29 adapted for fluid communication with a source of cooling fluid and a downstream exit. Third, a second cooling channel 30 is formed (such as by drilling or EDM) within the end region of the exit frame, with the second cooling channel positioned to intersect the first cooling channel 28. Fourth, a disruptive flow chamber 32 is formed (such as by machining) adjacent to, and flow-wise downstream of, said second cooling channel 30; the flow chamber has a downstream exit adapted for closure by a sealing element. Fifth, a chamber sealing cap 34 sized to seal the disruptive flow chamber 32 is obtained. Sixth, an exit channel 36 is formed (such as by drilling or EDM) in the sealing cap 34, with the exit channel having an entrance adapted to being offset radially, circumferen- tially, or radially and circumferentially from an exit of the second cooling channel. Seventh, the sealing cap 34 is positioned against a downstream opening of the flow chamber 32, and secured in place (such as by welding, laser welding, braz- ing, or other attachment method); it is noted that the entrance of the exit channel is offset from the exit of the second cooling channel 30, thereby providing a disrupted and controlled exit path for cooling fluid passing through the transition exit frame 26.

It is noted that the sixth and seventh steps may be reversed and that steps 5 through 7 may be performed on an existing transition exit frame, such as in a field repair or component upgrade situation.

While various embodiments of the present invention have been shown and described herein, it will be apparent that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.

Claims

CLAIMS What is claimed is:

1. A turbine engine transition exit frame having a cooling assembly comprising: a primary cooling channel in fluid communication with a source of cooling fluid; a turbulent flow chamber in fluid communication with said primary cooling path; a capping element constructed and arranged to form a fluid tight seal of said disruptive flow chamber; and

an exit channel disposed within said capping element,

whereby, said turbulent flow chamber and said exit channel cooling assembly are adapted to cooperatively provide impingement cooling of said capping ele ment.

2. The cooling assembly of Claim 1 , wherein said exit frame is subtractively man ufactured.

3. The cooling assembly of Claim 2, wherein said turbulent flow chamber is

formed via milling.

4. The cooling assembly of Claim 1 , wherein said exit channel has an entrance offset from an exit of said primary channel.

5. The cooling assembly of Claim 4, wherein said exit channel entrance is radially offset from said primary channel exit.

6. The cooling assembly of Claim 4, wherein said exit channel entrance is circum ferentially offset from said primary channel exit.

7. The cooling assembly of Claim 4, wherein said exit channel entrance is radially and circumferentially offset from said primary channel exit.

8. The cooling assembly of Claim 1 , wherein said capping element is secured via welding.

9. The cooling assembly of Claim 1 , wherein said capping element is secured via brazing.

10. The cooling assembly of Claim 1 , wherein said primary cooling channel is formed from a plurality of fluidly communicating sections.

11. The cooling assembly of Claim 10, wherein each of said sections is formed via electrical discharge machining.