US20170067365A1

US20170067365A1 - Exhaust frame strut with cooling fins

Info

Publication number: US20170067365A1
Application number: US14/849,112
Authority: US
Inventors: Debabrata Mukhopadhyay; Rohit Pruthi
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2015-09-09
Filing date: 2015-09-09
Publication date: 2017-03-09
Also published as: FR3040736A1; DE102016116603A1

Abstract

A system is provided including a turbine exhaust section. The turbine exhaust section includes an exhaust flow path. The turbine exhaust section also includes an outer structure having an outer casing and an outer exhaust wall disposed along the exhaust flow path. An inner structure of the turbine exhaust section includes an inner exhaust wall disposed along the exhaust flow path. A strut extends between the outer structure and the inner structure, and the strut is configured to convey a flow of fluid from the inner structure toward the outer structure. The strut includes a plurality of cooling fins to facilitate heat transfer from the strut to the flow of fluid.

Description

FIELD OF THE INVENTION

This invention relates generally to gas turbine cooling, and more particularly to exhaust section cooling.

BACKGROUND OF THE INVENTION

A gas turbine engine combusts a mixture of fuel and compressed air to generate hot combustion gases which drive turbine, blades thereby producing energy. The rotation of the turbine blades causes rotation of a shaft supported by bearings. The rotation of the shaft generates a significant amount of heat in the bearings. Additionally, the hot combustion gases exiting through the turbine exhaust section transfer heat w the turbine exhaust section components. Unfortunately, without adequate cooling in the turbine exhaust section, this heat may adversely influence the turbine components.

BRIEF SUMMARY OF THE INVENTION

One aspect of the disclosed technology relates to a turbine strut that includes a plurality of cooling fins to enhance efficiency of an exhaust section cooling system.
One exemplary but nonlimiting aspect of the disclosed technology relates to a strut for an exhaust section comprising an inner body that is load bearing, the inner body being configured to extend between an outer structure and an inner structure of the exhaust section, the inner body including a main portion and a plurality of cooling fins extending from the main portion; and an outer body configured to extend between the outer structure and the inner structure, of the exhaust section the inner body being disposed in an interior portion of the outer body such that a space is disposed between the main portion of the inner body and the outer body, wherein the space forms an airflow passageway configured to convey a flow of fluid toward the outer structure, and wherein the plurality of cooling fins extend into the airflow passageway and are configured to facilitate heat transfer from the inner body to the flow of fluid.
Another exemplary but nonlimiting aspect of the disclosed technology relates to a system for a gas turbine comprising, a turbine exhaust section, including: an exhaust flow path; an outer structure including an outer casing and an outer exhaust wall disposed along the exhaust flow path; an inner structure including an inner exhaust wall disposed along the exhaust flow path; a strut extending between the outer structure and the inner structure, the strut being configured to convey a flow of fluid from the inner structure toward the outer structure, wherein the strut includes a plurality a cooling fins disposed thereon to facilitate heat transfer from the strut to the flow of fluid.
Other aspects, features, and advantages of this technology will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the various examples of this technology. In such drawings:

FIG. 1 is a schematic flow diagram of an example turbine system having a gas turbine engine that may employ exhaust section cooling in accordance with an example of the disclosed technology:

FIG. 2 is a perspective view of an example exhaust section of a turbine system;

FIG. 3 is a schematic representation of a cross-sectional side view of the exhaust section of FIG. 2 illustrating exhaust section cooling in accordance with an example of the disclosed technology;

FIG. 4 is a perspective view of a strut in accordance with an example of the disclosed technology;

FIG. 5 is a perspective view of an inner body of a strut in accordance with an example of the disclosed technology;

FIG. 6 is a perspective view of an inner body of a strut in accordance with another example of the disclosed technology;

FIG. 7 is a cross-sectional view along the line 7-7 in FIG. 4;

FIG. 8 is a cross-section view similar to FIG. 7 in accordance with another example of the disclosed technology;

FIG. 9 is a cross-section view similar to FIG. 7 in accordance with another example of the disclosed technology; and

FIG. 10 is a cross-section view similar to FIG. 7 in accordance with another example of the disclosed technology.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Referring to FIG. 1, a schematic flow diagram of an example turbine system 10 is shown. The turbine system 10 has a gas turbine engine 12 that may employ exhaust section cooling. For example, the system 10 may include an exhaust section cooling system 11 having one or more cooling flow paths through an exhaust section strut. In certain examples, the turbine system 10 may include an aircraft, a locomotive, a power generation system, or combinations thereof.
The illustrated gas turbine engine 12 includes an air intake section 16, a compressor 18, a combustor section 20, a turbine 22, and an exhaust section 24, as shown in FIG. 1. The turbine 22 is coupled to the compressor 18 via a shaft 26. As indicated by the arrows, air may enter the gas turbine engine 12 through the intake section 16 and flow into the compressor 18, which compresses the air prior to entry into the combustor section 20.
The illustrated combustor section 20 includes a combustor housing 28 disposed concentrically or annularly about the shaft 26 between the compressor 18 and the turbine 22. The compressed air from the compressor 18 enters combustors 30, where the compressed air may mix and combust with fuel within the combustors 30 to drive the turbine 22. From the combustor section 20, the hot combustion gases flow through the turbine 22, driving the compressor 18 via the shaft 26. For example, the combustion gases may apply motive forces to turbine rotor blades within the turbine 22 to rotate the shaft 26. After flowing through the turbine 22, the hot combustion gases may exit the gas turbine engine 12 through the exhaust section 24. As described below, the exhaust section 24 may include a plurality of struts, each having one or more cooling flow paths of the exhaust section cooling system 11.
The exhaust section 24 may include an inner structure (i.e., inner barrel) 3$, at least one strut 40, and an outer structure (i.e., outer barrel) 42, as shown in FIG. 2. The strut 40 provides support between the outer structure 42 and the inner structure 38. As the hot combustion gases exit the turbine 22 and the shaft 26 rotates, the components in the exhaust section 24 may experience high temperature conditions. More specifically, the high temperature conditions may cause thermal stress, wear, and/or damage to the strut 40, the inner structure 38, and the outer structure 42. Accordingly, the exhaust section cooling system 11 may include a source 44 (e.g., a blower) coupled to a controller 46 which controls a cooling, air flow through the inner structure 38, the strut 40, and the outer structure 42 to reduce thermal stress and wear of these components and parts disposed therein, as shown in FIG. 3. Alternatively, the cooling air flow may be bled off from the compressor.
Referring to FIGS. 2-4, the strut 40 includes an outer body 48 and an inner body 50. In the illustrated example, the inner body 50 of the strut 40 is a load bearing structural support configured to bear a considerable mechanical load between the inner and outer structures 38 and 42 of the exhaust section 24, while the outer body 48 of the strut 40 is not a load bearing structural support. For example, the outer body 48 may be included to protect the inner body 50 by blocking heat from the inner body 50. In particular, the outer body 48 may be designed to flow cooling air externally along the inner body 50 to provide a thermal barrier between the inner body 50 and the hot combustion gases 31 in the exhaust section 24, a shown in FIG. 3. The inner body 50 and the outer body 48 may be made from any suitable materials, as those skilled in the art will understand
The outer body 48 also may have greater thermal resistance to the hot combustion gases 31 as compared to the inner body 50. For example, the inner body 50 may have a lower temperature limit than the outer body 48. In some embodiments, the inner body 50 may have a temperature limit lower than the temperature of the hot combustion gases 31, while the outer body 48 may have a temperature limit substantially above the temperature of the hot combustion gases. Thus, the outer body 48 thermally protects the inner body 50, such that the inner body 50 is able to effectively bear the mechanical load between the inner and outer structures 38 and 42 of the exhaust section 24.
Referring to FIG. 3, the inner structure 38 defines an inner exhaust wall 80, a bearing cavity 82, a bearing assembly (not shown) housed in a bearing housing 85, and an inner casing 83. The outer structure 42 includes an outer exhaust wall 106 and an outer casing 108, which define an intermediate Outer cavity 110 (e.g., an annular space). Hot combustion gases 31 pass along exhaust flow path 33. A cooling airflow 93 is conveyed to a space 43 between the inner body and the outer body 48 via openings 66 formed in the inner casing 83. Space 43 forms an airflow passageway that conveys the cooling airflow 93 from the inner structure 38 to the outer structure 42. As the cooling airflow 93 exits the strut 40, it may enter the outer cavity 110.
As shown in FIG. 4, the outer body 48 may have an airfoil shape, while the inner body 50 may be generally rectangular. In other examples, the inner and outer bodies 50, 48 may have other shapes, for example rectangular in rectangular, airfoil in airfoil, oval in oval, etc. Regardless of the particular shapes, the inner and outer bodies 50, 48 are disposed one inside another.
Referring to FIG. 5, the inner body 50 includes a main portion 53 and cooling fins 55 protruding from the main portion. The cooling fins 55 enhance the efficiency of the cooling airflow 93 which passes through the space 43 between the inner body 50 and the outer body 48. As those skilled in the art understand, the cooling fins 55 increase the external surface area of the inner body 50 and thus increase heat transfer from the inner body to the cooling airflow 93.
As efficiency of the cooling, airflow 93 is enhanced, the amount of airflow required to achieve a certain led of Ana cooling is reduced. Energy required to provide the cooling airflow directly impacts turbine efficiency. Thus, the cooling fins enable the power consumption of the airflow source (e.g., blower) to be reduced, thereby increasing turbine efficiency. It is possible that the need for a blower can be eliminated.
As shown in FIG. 5, the cooling fins 55 are elongate members extending in an axial direction of the exhaust section 24 thereby forming channels 57 between adjacent fins. A distance d1 between adjacent cooling fins 55 may be adjusted to manage the thermal gradient. Additionally, the distance d1 and/or a height (distance the cooling fins protrude from the main portion) of the cooling fins 55 may vary (e.g., in the radial direction) over the main body 53 to manage the radial thermal gradient.
The cooling fins 55 may extend over the entire radial length of the main portion 53, as shown in FIG. 4. It is noted, however, that the cooling fins 55 may be formed over only a partial radial length of the main portion. Likewise, the cooling fins 55 may extend over the full axial length or partial axial length of the main portion 53.
Referring to FIG. 6, inner body 150 includes a main portion 153 and cooling fins 155 protruding from the main portion. In contrast to inner body 50 of FIG. 5, cooling fins 155 extend in a radial direction of the exhaust section 24. Channels 157 are formed between adjacent cool mg tins 155. As mentioned above with regard to inner body 50, the configuration of cooling fins 155 may be varied over the main portion 153.
Referring to FIG. 7, the cooling airflow 93 may pass through the strut in the space 43 between the main portion 153 and the outer body 48. The outer body 48 has an inner surface 49 that faces the inner body 150. The inner surface 49 may have a coating applied thereto which has low thermal conductivity to reduce the heat that is transferred from the outer body 48 to the inner body 150. The coating may be any suitable thermal barrier coating, as those skilled in the art will understand
Turning to FIG. 8, an insulating material 45 may be disposed between the outer body 48 and the inner body 150 to reduce heat transfer from the outer body 48 to the inner body 150. In the example shown in FIG. 9, the insulating material 45 may abut tip portions of the cooling fins 155 such that the cooling airflow 93 may pass only along the channels 157. The insulating material 45 may be any suitable insulating material, e.g., silica fiber or glass wool.
In another example, an inner body 250 includes a main portion 253 and cooling fins 255 protruding from the main portion, as shown in FIG. 10. In contrast to the inner body 150 of FIGS. 6-9, inner body 250 also includes spacer fins 256. Spacer fins 256 extend a further distance from the main portion 253 than cooling fins 255 such that the insulating material 45 abuts the spacer fins 256 thereby forming a space 243 between the inner body 250 and the outer body 48. The cooling airflow 93 may pass along the space 243.
While the invention has been described in connection with what is presently considered to be the most practical and preferred examples, it is to be understood that the invention is not to be limited to the disclosed examples, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

What is claimed:

1. A strut for an exhaust section, comprising:

an inner body that is load bearing, the inner body being configured to extend between an outer structure and an inner structure of the exhaust section, the inner body including a main portion and a plurality of cooling fins extending from the main portion; and

an outer body configured to extend between the outer structure and the inner structure of the exhaust section, the inner body being disposed in an interior portion of the outer body such that a space is disposed between the main portion of the inner body and the outer body,

wherein the space forms an airflow passageway configured to convey a flow of fluid toward the outer structure, and

wherein the plurality of cooling fins extend into the airflow passageway and are configured to facilitate heat transfer from the inner body to the flow of fluid.

2. The strut according to claim 1, wherein the outer both has an inner surface which faces the inner body, and the inner surface has a coating with low thermal conductivity.

3. The strut according to claim 1, further comprising an insulating material disposed between the outer body and the main portion of the inner body.

4. The strut according to claim 3, wherein the insulating material contacts tip portions of the plurality of cooling fins such that the flow of fluid can pass along channels formed between adjacent cooling fins.

5. The strut according to claim 3, wherein a first portion of the plurality of cooling, fins protrude further from the main portion of the inner body than a second portion of the plurality of cooling fins.

6. The strut according to claim 5, wherein the insulating material contacts tip portions of the first portion of the plurality of cooling fins such that the flow of fluid can pass between the insulating material and the second portion of the plurality of cooling fins.

7. The strut according to claim 1, wherein each cooling fin of the plurality of cooling fins forms an elongate member extending in an axial direction of the exhaust section.

8. The strut according to claim 1, wherein each cooling fin of the plurality of cooling fins loans an elongate member extending in a radial direction of the exhaust section.

9. The strut according to claim 8, wherein a distance that the plurality of cooling fins extend from the main portion of the inner body varies along the radial direction.

10. The strut according to claim 1, wherein a distance between adjacent fins of the plurality of cooling fins varies over the main portion of the inner body.

11. A system for a gas turbine, comprising:

a turbine exhaust section, including:

an exhaust flow path;

an outer structure including an outer casing and an outer exhaust wall disposed along the exhaust flow path;

an inner structure including an inner exhaust wall disposed along the exhaust flow path;

a strut extending between the outer structure and the inner structure, the strut being configured to convey a flow of fluid from the inner structure toward the outer structure,

wherein the strut includes a plurality of cooling fins disposed thereon to facilitate heat transfer from the strut to the flow of fluid.

12. The system according to claim 11, wherein the strut includes an inner body that is load bearing and an outer body that is not load bearing.

13. The system according to claim 12, wherein the inner body includes a main portion, and the plurality of cooling fins extend from the main portion.

14. The system according to claim 13, wherein the inner body is disposed in an interior portion of the outer body such that a space is disposed between the main portion of the inner body and the outer body.

15. The system according to claim 14, wherein the space forms an airflow passageway configured to convey the flow of fluid toward the outer structure.

16. The system according to claim 15, wherein the plurality of cooling fins extend into the airflow passageway.

17. The system according to claim 13, further comprising an insulating material disposed between the outer body and die main portion of the inner body.

18. The system according to claim 12, wherein the outer body has an inner surface which faces the inner body, and the inner surface has a coating with low thermal conductivity.

19. The system according to claim 11, wherein each cooling fin of the plurality of cooling fins forms an elongate member extending in an axial direction or a radial direction of the turbine exhaust section.

20. A gas turbine, comprising:

a compressor;

a combustor section;

a turbine section; and

the system of claim 11.