HIGH-TURNING DIFFUSER STRUT WITH FLOW CROSS-OVER SLOTS
A turning strut for use in a diffuser of a turbine engine has a leading edge with first and second opposing surfaces depending therefrom that terminate at a trailing edge. Slots extend through the turning strut and reduce in volume from the first surface to the second surface. During turn down operation of the turbine engine, exhaust flow impacts the leading edge at a deviated swirl angle. This results in exhaust flow at the first surface being at a higher pressure than at the second surface, which causes exhaust flow to be induced through the slots. The reduction in slot volume causes exhaust flow through the slots to accelerate. This exhaust flow from the slots is combined with exhaust flow at the second surface. Thusly, momentum of exhaust flow at the second surface is increased to maintain the second laminar boundary layer at the second surface.
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The subject matter described herein relates to turbine engines, and, more specifically, to turning struts in a diffuser of a turbine engine.
A gas turbine engine includes a compressor having a plurality of compressor blades disposed on a shaft, with the compressor blades and shaft configured to define a decreasing volume. Airflow ingested into the gas turbine is compressed as it passes through the compressor. A plurality of combustors are disposed downstream of the compressor, where air and fuel are mixed and the fuel is ignited, as is known. A multi-stage turbine is disposed downstream of the combustors. First stages of the multi-stage turbine are defined by a plurality of turbine vanes disposed on the shaft of the compressor. Final stages of the multi-stage turbine are defined by a plurality of turbine vanes disposed on an output drive shaft, which rotates independently of the shaft of the compressor. The heated compressed air flow from the combustors turns the multi-stage turbine. The rotation of the first stages of the multi-stage turbine rotates the shaft of the compressor. The rotation of the final stages of the multi-stage turbine rotates the output drive shaft, which in turn drives a generator. A diffuser is disposed aft of the final stages of the multi-stage turbine and is configured to decelerate the exhaust flow and convert dynamic energy to a static pressure rise. The diffuser includes a plurality of turning struts that consist of a support strut encased by an aerodynamic faring. The turning struts turn a flow from the multi-stage turbine towards the axial direction when the gas turbine engine is operated within a designed performance range. The turning struts are disposed circumferentially within the annulus of the diffuser.
BRIEF DESCRIPTION OF THE INVENTIONAccording to one aspect of the invention, a turning strut for use in a diffuser of a turbine engine has a curved leading edge, a first tapered surface depending at one end thereof from the curved leading edge, a second tapered surface depending at one end thereof from the curved leading edge, and a trailing edge defined at the other ends of the first and second tapered surfaces. The second tapered surface is disposed opposite the first tapered surface. At least one slot extends through the turning strut from the first tapered surface to the second tapered surface. The at least one slot reduces in volume from the first tapered surface to the second tapered surface. The at least one slot is disposed proximate the curved leading edge.
According to another aspect of the invention, a method of turning a flow in a diffuser of a turbine engine includes impacting the flow at a leading edge of the turning strut, at a swirl angle that is deviated from a design point swirl angle. The method further includes defining a first laminar boundary layer at a first tapered surface of the turning strut from the flow thereat and defining a second laminar boundary layer at a second surface of the turning strut from the flow thereat. The first tapered surface depending at one end thereof from the leading edge. The second tapered surface depending at one end thereof from the leading edge. The second surface is disposed opposite the first surface. The deviated swirl angle results a pressure differential between the flow at the first and second surfaces. The flow at the first surface is at a higher pressure than the flow at the second surface. The method includes inducing the flow through at least one slot that extends through the turning strut from the first surface to the second surface. The flow through the at least one slot is from the first surface to the second surface and is a result of the pressure differential between the flow at the first and second surfaces. The method further includes accelerating the flow through the at least one slot by a reduction of volume of the at least one slot from the first surface to the second surface. The method still further includes combining the flow from the at least one slot with the flow at the second surface. Momentum of the flow at the second surface is increased to maintain the second laminar boundary layer at the second surface.
According to yet another aspect of the invention, a turning strut for use in a diffuser of a turbine engine has a generally elongated tear drop shape defined by a leading edge having first and second surfaces depending therefrom, the second surface being disposed opposite the first surface, and the first and second surfaces terminating at a trailing edge. At least one slot extends through the turning strut from the first surface to the second surface. The at least one slot reduces in volume from the first surface to the second surface. The at least one slot is disposed proximate the leading edge.
These and other advantages and features will become more apparent from the following description taken in conjunction with 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:
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 INVENTIONReferring to
Referring to
However, it is at times desirable to operate the gas turbine engine 10 below its designed performance range. This would include operation during off peak energy demand or other low energy demand conditions. When operated in this manner, often referred to as “turn-down” operation, the flow of exhaust about the turning struts 50′ is less than optimal.
Referring to
Referring to
Referring now to
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 it is only limited by the scope of the appended claims.
Claims
1. A turning strut for use in a diffuser of a turbine engine, the turning strut comprising:
- a curved leading edge;
- a first tapered surface depending at one end thereof from the curved leading edge;
- a second tapered surface depending at one end thereof from the curved leading edge, the second tapered surface being disposed opposite the first tapered surface;
- a trailing edge defined at an other ends of the first and second tapered surfaces; and
- at least one slot extending through the turning strut from the first tapered surface to the second tapered surface, the at least one slot reducing in volume from the first tapered surface to the second tapered surface, the at least one slot being disposed proximate the curved leading edge.
2. The turning strut of claim 1 wherein the at least one slot comprises a plurality of slots that are aligned.
3. The turning strut of claim 1 wherein the at least one slot has a generally rectangular shape with rounded ends.
4. The turning strut of claim 1 wherein the at least one slot has a generally compound curve shape.
5. The turning strut of claim 4 wherein the generally compound curve shape comprises a serpentine shape.
6. The turning strut of claim 1 wherein the at least one slot is disposed proximate the curved leading edge so as to maintain a laminar boundary layer at the second tapered surface during turn down operation of the turbine engine.
7. A method of turning a flow in a diffuser of a turbine engine, the method comprising:
- impacting the flow at a leading edge of the turning strut, at a swirl angle that is deviated from a design point swirl angle;
- defining a first laminar boundary layer at a first tapered surface of the turning strut from the flow thereat, the first tapered surface depending at one end thereof from the leading edge;
- defining a second laminar boundary layer at a second surface of the turning strut from the flow thereat, the second tapered surface depending at one end thereof from the leading edge, the second surface being disposed opposite the first surface, wherein the deviated swirl angle results a pressure differential between the flow at the first and second surfaces, wherein the flow at the first surface is at a higher pressure than the exhaust flow at the second surface;
- inducing the flow through at least one slot that extends through the turning strut from the first surface to the second surface, the flow through the at least one slot is from the first surface to the second surface and is a result of the pressure differential between the flow at the first and second surfaces;
- accelerating the flow through the at least one slot by a reduction of volume of the at least one slot from the first surface to the second surface; and
- combining the flow from the at least one slot with the flow at the second surface, wherein momentum of the flow at the second surface is increased to maintain the second laminar boundary layer at the second surface.
8. The method of claim 7 further comprising:
- turning down the turbine engine, wherein the swirl angle of the flow deviates from the design point swirl angle.
9. The method of claim 7 wherein the at least one slot comprises a plurality of slots that are aligned.
10. The method of claim 7 wherein the at least one slot has a generally rectangular shape with rounded ends.
11. The method of claim 7 wherein the at least one slot has a generally compound curve shape.
12. The method of claim 11 wherein the generally compound curve shape comprises a serpentine shape.
13. The method of claim 7 wherein the first and second surfaces terminate at a trailing edge.
14. A turning strut for use in a diffuser of a turbine engine, the turning strut having a generally elongated tear drop shape defined by a leading edge having first and second surfaces depending therefrom, the second surface being disposed opposite the first surface, the first and second surfaces terminating at a trailing edge, at least one slot extending through the turning strut from the first surface to the second surface, the at least one slot reducing in volume from the first surface to the second surface, the at least one slot being disposed proximate the leading edge.
15. The turning strut of claim 14 wherein the at least one slot comprises a plurality of slots that are aligned.
16. The turning strut of claim 14 wherein the at least one slot has a generally rectangular shape with rounded ends.
17. The turning strut of claim 14 wherein the at least one slot has a generally compound curve shape.
18. The turning strut of claim 17 wherein the generally compound curve shape comprises a serpentine shape.
19. The turning strut of claim 14 wherein the at least one slot is disposed proximate the curved leading edge so as to maintain a laminar boundary layer at the second tapered surface during turn down operation of the turbine engine.
Type: Application
Filed: Sep 3, 2009
Publication Date: Mar 3, 2011
Applicant: GENERAL ELECTRIC COMPANY (Schenectady, NY)
Inventor: Scott Matthew Sparks (Greenville, SC)
Application Number: 12/553,443
International Classification: F01D 5/14 (20060101);