US20140314549A1

US20140314549A1 - Flow manipulating arrangement for a turbine exhaust diffuser

Info

Publication number: US20140314549A1
Application number: US13/864,748
Authority: US
Inventors: Srinivas Rao Pakkala; Manjunath Bangalore Chengappa; Kamlesh Mundra; Antanu Sadhu; Kunal Upendra Sakekar; Moorthi Subramaniyan; Lisa Anne Wichmann
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2013-04-17
Filing date: 2013-04-17
Publication date: 2014-10-23
Also published as: CN203891945U; DE102014104318A1; JP2014211159A; CH708006A2

Abstract

A flow manipulating arrangement for a turbine exhaust diffuser includes a strut having a leading edge and a trailing edge, the strut disposed within the turbine exhaust diffuser. Also included is a plurality of rotatable guide vanes disposed in close proximity to the strut and configured to manipulate an exhaust flow, wherein the plurality of rotatable guide vanes is coaxially aligned and circumferentially arranged relative to each other. Further included is an actuator in operative communication with the plurality of rotatable guide vanes and configured to actuate an adjustment of the plurality of rotatable guide vanes. Yet further included is a circumferential ring operatively coupling the plurality of rotatable guide vanes, wherein the actuator is configured to directly actuate rotation of one of the rotatable guide vanes, and wherein the circumferential ring actuates rotation of the plurality of rotatable guide vanes upon rotational actuation by the actuator.

Description

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to turbine systems, and more particularly to boundary layer flow control of turbine exhaust diffuser components.
Typical turbine systems, such as gas turbine systems, for example, include an exhaust diffuser coupled to a turbine section of the turbine system to increase efficiency of a last stage bucket of the turbine section. The exhaust diffuser is geometrically configured to rapidly decrease the kinetic energy of flow and increase static pressure recovery within the exhaust diffuser.
Commonly, the exhaust diffuser is designed for full load operation, however, the turbine system is often operated at part load or on a cold day. Therefore, part load performance efficiency is sacrificed, based on the full load design. Inefficiency is due, at least in part, to flow separation on exhaust diffuser components, such as walls and struts, for example. Flow separation often is caused, in part, by swirling of the flow upon exit of the last bucket stage of the turbine section and entry into the exhaust diffuser. The magnitude of swirl may be quantified as a “tangential flow angle,” and such an angle may be up to about 60 degrees during part load and 20 degrees during a cold day, which leads to a higher angle of attack on the exhaust diffuser components, such as the struts, for example. Such a flow characteristic leads to boundary layer growth and flow separation and eventually reduced pressure recovery

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a flow manipulating arrangement for a turbine exhaust diffuser includes a strut having a leading edge and a trailing edge, the strut disposed within the turbine exhaust diffuser. Also included is a plurality of rotatable guide vanes disposed in close proximity to the strut and configured to manipulate an exhaust flow, wherein the plurality of rotatable guide vanes is coaxially aligned and circumferentially arranged relative to each other. Further included is an actuator in operative communication with the plurality of rotatable guide vanes and configured to actuate an adjustment of the plurality of rotatable guide vanes. Yet further included is a circumferential ring operatively coupling the plurality of rotatable guide vanes, wherein the actuator is configured to directly actuate rotation of one of the rotatable guide vanes, and wherein the circumferential ring actuates rotation of the plurality of rotatable guide vanes upon rotational actuation by the actuator.
According to another aspect of the invention, a flow manipulating arrangement for a turbine exhaust diffuser includes an inner barrel extending in a longitudinal direction of the turbine exhaust diffuser. Also included is an outer wall disposed radially outwardly of the inner barrel. Further included is a strut extending between, and operatively coupled to, the inner barrel and the outer wall, wherein the strut comprises a leading edge and a trailing edge. Yet further included is at least one guide vane disposed axially upstream of the leading edge or downstream of the trailing edge of the strut, the at least one guide vane selectively circumferentially displaceable relative to the strut.
According to yet another aspect of the invention, a flow manipulating arrangement for a radial turbine exhaust diffuser includes an inner wall. Also included is an outer wall. Further included is a strut operatively coupled to at least one of the inner wall and the outer wall. Yet further included is at least one rotatable guide vane disposed proximate the strut, wherein the at least one rotatable guide vane is selectively rotatable over a range of angular positions and displaceable in at least one of an axial direction and a radial direction.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic illustration of a turbine system;

FIG. 2 is a perspective view of a flow manipulation arrangement according to a first embodiment;

FIG. 3 is a side, schematic view of the flow manipulation arrangement of FIG. 2;

FIG. 4 is top view of guide vanes and struts of the flow manipulation arrangement of FIG. 2;

FIG. 5 is a top view of a plurality of guide vanes operatively coupled;

FIG. 6 is a perspective, schematic view of the plurality of guide vanes operatively coupled;

FIG. 7 is a perspective view of the flow manipulation arrangement according to a second embodiment;

FIG. 8 is a front elevational view of the flow manipulation arrangement of FIG. 7;

FIG. 9 is a top view of the flow manipulation arrangement of FIG. 7;

FIG. 10 is a top view of the flow manipulation arrangement according to a third embodiment illustrating guide vanes in a first position;

FIG. 11 is a top view of the flow manipulation arrangement of FIG. 10 illustrating guide vanes in a second position;

FIG. 12 is a schematic illustration of a control mechanism of the flow manipulation arrangement of FIG. 10; and

FIG. 13 is a schematic illustration of the flow manipulation arrangement according to a fourth embodiment.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a turbine system, such as a gas turbine system, for example, is schematically illustrated with reference numeral 10. The turbine system 10 includes a compressor section 12, a combustor section 14, a turbine section 16, a shaft 18 and a fuel nozzle 20. It is to be appreciated that one embodiment of the turbine system 10 may include a plurality of compressors 12, combustors 14, turbines 16, shafts 18 and fuel nozzles 20. The compressor section 12 and the turbine section 16 are coupled by the shaft 18. The shaft 18 may be a single shaft or a plurality of shaft segments coupled together to form the shaft 18.
The combustor section 14 uses a combustible liquid and/or gas fuel, such as natural gas or a hydrogen rich synthetic gas, to run the turbine system 10. For example, fuel nozzles 20 are in fluid communication with an air supply and a fuel supply 22. The fuel nozzles 20 create an air-fuel mixture, and discharge the air-fuel mixture into the combustor section 14, thereby causing a combustion that creates a hot pressurized exhaust gas. The combustor section 14 directs the hot pressurized gas through a transition piece into a turbine nozzle (or “stage one nozzle”), and other stages of buckets and nozzles causing rotation of turbine blades within an outer casing 24 of the turbine section 16. Subsequently, the hot pressurized gas is sent from the turbine section 16 to an exhaust diffuser 26 that is operably coupled to a portion of the turbine section, such as the outer casing 24, for example.
Although illustrated and described above as a gas turbine system, it is to be appreciated that the turbine system 10 may alternatively be a steam turbine system. As will be described below, various embodiment of the exhaust diffuser 26 are contemplated, such as an axial exhaust diffuser and a radial exhaust diffuser.
Referring now to FIGS. 2 and 3, a first embodiment of a flow manipulating arrangement 50 is illustrated within the exhaust diffuser 26. In the illustrated embodiment, the exhaust diffuser 26 is an axial exhaust diffuser disposed axially downstream of a last stage of the turbine section 16. The exhaust diffuser 26 includes an inlet 28 configured to receive an exhaust flow 30 from the turbine section 16. An outlet 32 is disposed at a downstream location relative to the inlet 28. Extending relatively axially along a longitudinal direction of the exhaust diffuser 26 at least partially between the inlet 28 and the outlet 32 is an inner barrel 34 that includes an outer surface 36. Spaced radially outwardly from the inner barrel 34, and more specifically radially outwardly from the outer surface 36, is an outer wall 38 having an inner surface 40. The outer wall 38 may be arranged in a relatively diverging configuration, such that kinetic energy of the exhaust flow 30 is lessened subsequent to entering the inlet 28 of the exhaust diffuser 26. More particularly, a transfer of dynamic pressure to static pressure occurs within the exhaust diffuser 26 due to the diverging configuration of the outer wall 38. The exhaust flow 30 flows through the area defined by the outer surface 36 of the inner barrel 34 and the inner surface 40 of the outer wall 38.
Also disposed between the outer surface 36 of the inner barrel 34 and the inner surface 40 of the outer wall 38 is at least one, but typically a plurality of struts 42, with exemplary embodiments including a number of struts ranging from four (4) to twelve (12) struts circumferentially spaced from each other in a coaxial alignment. The plurality of struts 42 serves to hold the inner barrel 34 and the outer wall 38 in a fixed relationship to one another, as well as providing bearing support. As the strut 42 is disposed within the area between the inner barrel 34 and the outer wall 38, the exhaust flow 30 passes over the strut 42. Therefore, the strut 42 influences the flow characteristics of the exhaust flow 30, and hence the overall exhaust diffuser performance. The plurality of struts 42 is shaped as or surrounded by an airfoil, and it is to be appreciated that the precise geometry and dimensions of the plurality of struts 42 may vary from that illustrated, based on the application. Each of the plurality of struts 42 includes a leading edge 44 and a trailing edge 46.
As the exhaust flow 30 exits the turbine section 16, the last stage bucket exit tangential flow angle (FIG. 4) of the exhaust flow 30 increases based on the diverging configuration of the outer wall 38 of the exhaust diffuser 26, as well as various operating conditions, thereby leading to flow separation in regions proximate the outer surface 36 of the inner barrel 34, as well as regions proximate the various outer surfaces of the plurality of struts 42. To reduce the flow separation described above, the exhaust flow 30 is manipulated by the flow manipulating arrangement 50, as described in detail below.
Referring to FIGS. 4 and 5, in conjunction with FIGS. 2 and 3, the flow manipulating arrangement 50 comprises at least one, but typically a plurality of rotatable guide vanes 52 circumferentially spaced from each other and coaxially aligned. As described above, the plurality of struts 42 is disposed in an axial location, such that the struts are coaxially aligned. The plurality of rotatable guide vanes 52 is disposed proximate the plurality of struts 42 and at a location axially upstream of the plurality of struts 42. The plurality of rotatable guide vanes 52 comprises an airfoil-shaped geometry and is operatively coupled to the inner barrel 34 and/or the outer wall 38 for support. One or more sealing components 41 may be disposed between the plurality of rotatable guide vanes 52 and the inner barrel 34 and/or the outer wall 38 for sealing at an interface therebetween. The plurality of rotatable guide vanes 52 each include a rotatable member 54, such as a spindle or rod, operatively coupled thereto. In one embodiment, the rotatable member 54 extends in a radial direction through a portion of the plurality of rotatable guide vanes 52. The rotatable member 54 is also operatively coupled to an actuator assembly 56 (FIG. 2) configured to actuate rotation of the rotatable member 54. In particular, the actuator assembly 56 may be directly coupled to the rotatable member 54, such as via an output shaft or gear of the actuator assembly 56, or indirectly coupled to the rotatable member 54 via a gear arrangement and/or cable arrangement, generally referred to as 58. The actuator assembly 56 refers to various motors, including a servo motor. Alternatively, a pneumatic actuator may actuate adjustment of the rotatable member 54. In one embodiment, the rotatable member 54 is coupled to the inner barrel 34 and/or outer wall 38 with a bushing or bearing arrangement mounted to the inner barrel 34 and/or outer wall 38.
The plurality of rotatable guide vanes 52 is rotatable about an axis defined by the rotatable member 54 over a range of angular positions. The range of angular positions advantageously provides numerous positions of the plurality of rotatable guide vanes 52, thereby accounting for various flow angles of the exhaust flow 30. Specifically, the plurality of struts 42 is aligned in a direction to provide efficient flow characteristics of the exhaust flow 30 within the exhaust diffuser 26 at certain operating conditions, such as a base load, or full-speed, full-load operating condition. However, flow angles of the exhaust flow 30 differ at other operating conditions, such as a part load operating condition, for example. In the alternate operating conditions, efficiency is reduced due to an increase in boundary layer formation. By rotating the plurality of rotatable guide vanes 52 to positions corresponding to appropriate flow manipulating positions, the exhaust flow 30 is manipulated in what is referred to as a “straightening” manner, which results in a desirable flow angle of the exhaust flow 30 upon passage over the plurality of struts 42.
In one embodiment, with reference to FIGS. 5 and 6, a circumferential segment of rotatable guide vanes 60 comprises operatively coupled rotatable guide vanes arranged in a “ganged” relationship. The circumferential segment of rotatable guide vanes 60 comprises two or more guide vanes operatively coupled by a circumferential ring 62. It is contemplated that any number of a plurality of guide vanes may form the circumferential segment of rotatable guide vanes 60. The ganged arrangement allows the actuator assembly 56 and the gear arrangement and/or cable arrangement 58 to directly impart rotation of a single rotatable member, while indirectly rotating the additional guide vanes of the circumferential segment of rotatable guide vanes 60 via the circumferential ring 62. The circumferential ring 62 forms a rack and pinion arrangement with additional rotatable members to facilitate rotation of the additional guide vanes via a toothed gear arrangement between the circumferential ring 62 and the additional rotatable members of each guide vane. Alternatively, or in combination with the rack and pinion arrangement, the circumferential ring 62 may be operative coupled to one or more bearings 63 (FIG. 6) that facilitate sliding of the circumferential ring 62 within a slot structure 65, thereby driving a rotational motion of each of the rotatable guide vanes about the rotatable member 54 of the respective rotatable guide vanes.
As described above, the plurality of rotatable guide vanes 52 is rotatable over a range of angular positions. The range of angular positions corresponds to a range of operating conditions of the turbine system 10, and more specifically a range of angles of tangential flow of the exhaust flow 30. For example, a first position corresponds to a first condition and a second position corresponds to a second condition. The first position of the plurality of rotatable guide vanes 52 is relatively parallel to the plurality of struts 42 at a first condition corresponding to a full-speed, full-load operating condition of the turbine system 10. As the speed of the turbine system 10 is reduced to a part load condition, such as 60% speed, for example, the plurality of rotatable guide vanes 52 are rotated to an angle that provides desirable manipulation of the exhaust flow 30 to straighten for flow over the plurality of struts 42.
Referring now to FIGS. 7-9, a flow manipulation arrangement 100 according to a second embodiment is illustrated. The second embodiment is similar in many respects to the first embodiment described in detail above, such that duplicative description of each component is not necessary and similar reference numerals are employed where applicable. Additionally, the second embodiment is employed in conjunction with an axial exhaust diffuser, such as the exhaust diffuser 26 described in detail above. In the second embodiment, the plurality of rotatable guide vanes 52 is disposed circumferentially adjacent to, but coaxially aligned with the plurality of struts 42. As shown, at least a portion of the plurality of rotatable guide vanes 52 is disposed at substantially the same axial location of at least a portion of the plurality of struts 42, including the leading edge 44 and/or the trailing edge 46 of the plurality of struts 42. It is contemplated that the rotatable guide vanes and the struts may be arranged in an alternating arrangement in a one-to-one ratio, or alternatively more than one rotatable guide vane may be disposed between the struts. Additionally, as is the case with the first embodiment, one or more sealing components 41 are disposed at an interface between the plurality of rotatable guide vanes 52 and the inner barrel 34 and/or the outer wall 38.
Referring now to FIGS. 10-12, a flow manipulation arrangement 200 according to a third embodiment is illustrated. The third embodiment is employed in conjunction with an axial exhaust diffuser, such as the exhaust diffuser 26 described in detail above. The third embodiment includes a plurality of guide vanes 202 circumferentially spaced from each other and coaxially aligned. Additionally, the plurality of guide vanes 202 is disposed in at least one axial stage, which may be axially upstream and/or downstream of the plurality of struts 42.
Each of the plurality of guide vanes 202 are aligned in a substantially parallel alignment with the plurality of struts 42, but each stage of guide vanes is adjustable in a circumferentially displaceable manner. Specifically, the plurality of guide vanes 202 are “clocked” to alter their alignment with the plurality of struts 42. For example, in a first position (FIG. 10), the plurality of guide vanes 202 is circumferentially aligned with the plurality of struts 42 and in a second position (FIG. 11), the plurality of guide vanes 202 is circumferentially misaligned with the plurality of struts 42. As described above, the first position and the second position are advantageous at different operating conditions of the turbine system 10.
As is the case with the previous embodiments described, the flow manipulation arrangement 200 is actuated with an actuator arrangement 204, such as one or more motors that directly or indirectly interact with a circumferential ring 206 that controls the position of the plurality of guide vanes 202.
Referring now to FIG. 13, a flow manipulation arrangement 300 according to a fourth embodiment is illustrated. The fourth embodiment is similar in many respects to the first and second embodiments described in detail above, such that duplicative description of each component is not necessary and similar reference numerals are employed where applicable. However, in contrast to the axial exhaust diffuser of the first and second embodiments, the fourth embodiment is employed in conjunction with a radial exhaust diffuser 302. The radial exhaust diffuser 302 comprises either a steam turbine diffuser or a gas turbine diffuser. The radial exhaust diffuser 302 includes an inner wall 304 and an outer wall 306, with at least one strut 308 operatively coupled to at least one of the inner wall 304 and the outer wall 306. At least one guide vane 310 is operatively coupled to the at least one strut 308, and as is the case with the previous embodiments comprising rotatable guide vanes, the at least one guide vane 310 is rotatable over a range of angular positions that corresponds to a range of exhaust flow conditions. Additionally, the at least one guide vane 310 is selectively displaceable in the axial direction and/or the radial direction.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims

1. A flow manipulating arrangement for a turbine exhaust diffuser comprising:

a strut having a leading edge and a trailing edge, the strut disposed within the turbine exhaust diffuser;

a plurality of rotatable guide vanes disposed in close proximity to the strut and configured to manipulate an exhaust flow, wherein the plurality of rotatable guide vanes is coaxially aligned and circumferentially arranged relative to each other;

an actuator in operative communication with the plurality of rotatable guide vanes and configured to actuate an adjustment of the plurality of rotatable guide vanes; and

a circumferential ring operatively coupling the plurality of rotatable guide vanes, wherein the actuator is configured to directly actuate rotation of one of the rotatable guide vanes, and wherein the circumferential ring actuates rotation of the plurality of rotatable guide vanes upon rotational actuation by the actuator.

2. The flow manipulating arrangement of claim 1, wherein the turbine exhaust diffuser is an axial diffuser comprising:

an inner barrel extending in a longitudinal direction of the turbine exhaust diffuser; and

an outer wall disposed radially outwardly of the inner barrel, wherein the strut extends between, and is operatively coupled to, the inner barrel and the outer wall, and wherein the plurality of rotatable guide vanes is operatively coupled to at least one of the inner barrel and the outer wall.

3. The flow manipulating arrangement of claim 2, further comprising a rotatable member operatively coupled to the actuator and extending through each of the plurality of rotatable guide vanes, wherein the plurality of rotatable guide vane is rotatable about an axis defined by the rotatable member.

4. The flow manipulating arrangement of claim 2, further comprising a plurality of struts coaxially aligned and circumferentially arranged wherein the plurality of rotatable guide vanes is disposed in at least one of an axially upstream location and an axially downstream location of the plurality of struts.

5. The flow manipulating arrangement of claim 1, wherein the circumferential ring is operatively coupled to a plurality of bearings configured to facilitate sliding of the circumferential ring within a slot structure.

6. The flow manipulating arrangement of claim 2, wherein the plurality of rotatable guide vanes is circumferentially adjacent to, and axially aligned with, the strut.

7. The flow manipulating arrangement of claim 1, wherein the plurality of rotatable guide vanes is rotatable over a range of angular positions corresponding to a range of exhaust flow conditions.

8. The flow manipulating arrangement of claim 7, wherein the range of angular positions comprises a first position corresponding to a first condition and a second position corresponding to a second condition, wherein the first condition comprises a full speed, full load condition and the second condition comprises a part load condition.

9. The flow manipulating arrangement of claim 3, further comprising a gear arrangement configured to transmit mechanical power from the actuator to the rotatable member.

10. The flow manipulating arrangement of claim 1, wherein the turbine exhaust diffuser is a radial diffuser comprising an inner wall and an outer wall, wherein the strut is operatively coupled to at least one of the inner wall and the outer wall.

11. The flow manipulating arrangement of claim 10, wherein the plurality of rotatable guide vanes is operatively coupled to the strut.

12. The flow manipulating arrangement of claim 10, wherein the plurality of rotatable guide vanes is rotatable over a range of angular positions corresponding to a range of exhaust flow conditions.

13. The flow manipulating arrangement of claim 2, further comprising:

an outer seal arrangement disposed between the plurality of rotatable guide vanes and the outer wall; and

an inner seal arrangement disposed between the plurality of rotatable guide vanes and the inner barrel.

14. The flow manipulating arrangement of claim 2, wherein the plurality of rotatable guide vanes is moveable in a radial direction.

15. A flow manipulating arrangement for a turbine exhaust diffuser comprising:

an inner barrel extending in a longitudinal direction of the turbine exhaust diffuser;

an outer wall disposed radially outwardly of the inner barrel;

a strut extending between, and operatively coupled to, the inner barrel and the outer wall, wherein the strut comprises a leading edge and a trailing edge; and

at least one guide vane disposed axially upstream of the leading edge of the strut, the at least one guide vane selectively circumferentially displaceable relative to the strut.

16. The flow manipulating arrangement of claim 15, further comprising a motor in operative communication with the at least one guide vane and configured to actuate an adjustment of the at least one guide vane.

17. The flow manipulating arrangement of claim 15, further comprising a plurality of struts coaxially aligned and circumferentially arranged, wherein the at least one guide vane comprises a plurality of guide vanes coaxially aligned and circumferentially arranged.

18. The flow manipulating arrangement of claim 17, wherein the plurality of guide vanes are circumferentially aligned with the plurality of struts in a first position during a first condition of an exhaust flow and displaceable to at least one additional position during a second condition of the exhaust flow.

19. The flow manipulating arrangement of claim 15, further comprising a plurality of struts coaxially aligned and circumferentially arranged, wherein the at least one guide vane comprises a plurality of guide vanes coaxially aligned and circumferentially arranged at an axially downstream location of the plurality of struts.

20. A flow manipulating arrangement for a radial turbine exhaust diffuser comprising:

an inner wall;

an outer wall;

a strut operatively coupled to at least one of the inner wall and the outer wall; and

at least one rotatable guide vane disposed proximate the strut, wherein the at least one rotatable guide vane is selectively rotatable over a range of angular positions and displaceable in at least one of an axial direction and a radial direction.