U.S. patent application number 10/603036 was filed with the patent office on 2004-12-30 for cooling of combustion turbine airfoil fillets.
This patent application is currently assigned to Siemens Westinghouse Power Corporation. Invention is credited to Scott, Robert Kenmer, Tapley, Joseph Theodore.
Application Number | 20040265128 10/603036 |
Document ID | / |
Family ID | 33418647 |
Filed Date | 2004-12-30 |
United States Patent
Application |
20040265128 |
Kind Code |
A1 |
Scott, Robert Kenmer ; et
al. |
December 30, 2004 |
COOLING OF COMBUSTION TURBINE AIRFOIL FILLETS
Abstract
A turbine fluid guide member (10) including an airfoil portion
(12), a platform portion (14) and fillet (16) joining the airfoil
portion to the platform portion. Fillet cooling holes (18a-18f) are
positioned in the turbine fluid guide member relative to a pressure
side vortex flow (22) so that a cooling fluid flow (20) exiting the
hole is directed to form a cooling film (32) over the fillet. The
cooling holes may be positioned in the airfoil portion, the
platform portion, or any combination thereof, depending on the
geometry of the airfoil and resultant vortex flows around the
airfoil. A method of cooling a fillet of the turbine fluid guide
member may include identifying a vortex flow around the fillet and
selectively positioning a hole relative to the vortex flow such
that a cooling fluid flow exiting the hole is directed to form a
cooling film over the fillet.
Inventors: |
Scott, Robert Kenmer;
(Geneva, FL) ; Tapley, Joseph Theodore; (Winter
Springs, FL) |
Correspondence
Address: |
Siemens Corporation
Intellectual Property Department
170 Wood Avenue South
Iselin
NJ
08830
US
|
Assignee: |
Siemens Westinghouse Power
Corporation
|
Family ID: |
33418647 |
Appl. No.: |
10/603036 |
Filed: |
June 24, 2003 |
Current U.S.
Class: |
416/97R |
Current CPC
Class: |
F05D 2270/17 20130101;
F05D 2260/202 20130101; F01D 5/145 20130101; F01D 5/186 20130101;
F05D 2260/2214 20130101; F05D 2240/81 20130101 |
Class at
Publication: |
416/097.00R |
International
Class: |
B63H 001/14 |
Claims
What is claimed is:
1. A turbine fluid guide member comprising: an airfoil portion; a
platform portion; a fillet joining the airfoil portion to the
platform portion; and a coolant outlet positioned remotely from the
fillet such that a cooling flow exiting the outlet is directed by a
vortex flow to form a cooling film over the fillet.
2. The turbine fluid guide member of claim 1, wherein the coolant
outlet comprises a hole positioned in the airfoil portion proximate
the fillet.
3. The turbine fluid guide member of claim 1, wherein the coolant
outlet comprises a hole positioned in the platform portion
proximate the fillet.
4. The turbine fluid guide member of claim 1, wherein the airfoil
portion comprises a stationary vane.
5. The turbine fluid guide member of claim 1, wherein the airfoil
portion comprises a rotating blade.
6. The turbine fluid guide member of claim 1, further comprising a
plurality of spaced apart coolant outlets disposed longitudinally
so that the cooling film is maintained below a predetermined
temperature along a length of the fillet.
7. A turbine fluid guide member comprising: an airfoil having
pressure and suction sides; a platform; a fillet joining the
airfoil to the platform; a plurality of holes formed in the airfoil
directing a coolant flow into a first vortex flow to create a first
cooling film along a first portion of the fillet on a first one of
the pressure and vortex sides.
8. The turbine guide member of claim 7, further comprising a
plurality of holes formed in the platform directing the coolant
flow into a second vortex flow to create a second cooling film
along a second portion of the fillet on a second one of the
pressure and suction sides.
9. A combustion turbine engine comprising: a compressor; a turbine;
a combustor; and a turbine fluid guide member comprising an airfoil
portion, a platform portion, a fillet joining the airfoil portion
to the platform portion, and a coolant outlet positioned remote
from the fillet such that a cooling flow exiting the outlet is
directed by a vortex flow to form a cooling film over the
fillet.
10. A method for cooling a portion of a turbine fluid guide member
comprising: identifying a vortex flow around the turbine fluid
guide member; and selectively positioning a coolant outlet relative
to the vortex flow such that a cooling flow exiting the outlet is
directed by the vortex flow to form a cooling film over a fillet
portion of the turbine fluid guide member.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to combustion turbine
engines, and, in particular, to cooling of turbine fluid guide
members.
BACKGROUND OF THE INVENTION
[0002] In a typical combustion turbine engine, a variety of vortex
flows are generated around airfoil elements within the turbine.
FIG. 1 is a perspective view of a cut-away of several turbine
airfoil portions 1 showing hot combustion fluid flow 3 around the
airfoil portions 1. It is known that "horseshoe" vortices,
including a pressure side vortex 4, and a suction side vortex 5,
are formed when a hot combustion fluid flow 3 collides with the
leading edges 6 of the airfoil portions 1. The vortices 4,5 are
formed according to the particular geometry of the airfoil portions
1, and the spacing between the airfoil portions 1 mounted on the
platform 2. As the hot combustion fluid flow 3 splits into the
pressure side vortex 4 and a suction side vortex 5, the vortices
4,5 rotate in directions that sweep downward from the respective
side of the airfoil portion 1 to the platform 2. On the pressure
side 8 of the airfoil portions 1, the pressure side vortex 4 is the
predominant vortex, sweeping downward as the pressure side vortex 4
passes by the airfoil portion 1. As shown, the pressure side vortex
4 crosses from the pressure side 8 of the airfoil portion 1 to the
suction side 7 of an adjacent airfoil portion 1. In addition, the
pressure side vortex 4 increases in strength and size as it crosses
from the pressure side 8 to the suction side 7. Upon reaching the
suction side 7, the pressure side vortex 4 is substantially
stronger than the suction side vortex 5 and is spinning in a
rotational direction opposite from the suction side vortex 5. On
the suction side 7, the pressure side vortex 4 sweeps up from the
platform 2 towards the airfoil portion 1. Consequently, because the
pressure side vortex 4 is substantially stronger that the suction
side vortex 5, the resultant, or combined flow of the two vortices
4, 5 along the suction side 7 is radially directed to sweep up from
the platform 2 towards the airfoil portion 1.
[0003] A conventional approach to cooling fluid guide members, such
as airfoils in combustion turbines, is to provide cooling fluid,
such as high pressure cooling air from the intermediate or last
stages of the turbine compressor, to a series of internal flow
passages within the airfoil. In this manner, the mass flow of the
cooling fluid moving through passages within the airfoil portion
provides backside convective cooling to the material exposed to the
hot combustion gas. In another cooling technique, film cooling of
the exterior of the airfoil can be accomplished by providing a
multitude of cooling holes in the airfoil portion to allow cooling
fluid to pass from the interior of the airfoil to the exterior
surface. The cooling fluid exiting the holes form a cooling film,
thereby insulating the airfoil from the hot combustion gas. While
such techniques appear to be effective in cooling the airfoil
region, little cooling is provided to the fillet region where the
airfoil is joined to a mounting platform.
[0004] The fillet region is important in controlling stresses where
the airfoil is joined to the platform. Although larger fillets can
lower stresses at the joint, such as disclosed in U.S. Pat. No.
6,190,128, the resulting larger mass of material is more difficult
to cool through indirect means. Accordingly, prohibitively large
amounts of cooling flow may need to be applied to the region of the
fillet to provide sufficient cooling. If more cooling flow for film
cooling is provided to the airfoil in an attempt to cool the fillet
region, a disproportionate amount of cooling fluid may be diverted
from the compressor system, reducing the efficiency of the engine
and adversely affecting emissions. While forming holes in the
fillet to provide film cooling directly to the fillet region would
improve cooling in this region, it is not feasible to form holes in
the fillet because of the resulting stress concentration that would
be created in this highly stressed area.
[0005] Backside impingement cooling of the fillet region has been
proposed in U.S. Pat. No. 6,398,486. However, this requires
additional complexity, such as an impingement plate mounted within
the airfoil portion. In addition, the airfoil portion walls in the
fillet region are generally thicker, which greatly reduces the
effectiveness of backside impingement cooling.
[0006] Accordingly, there is a need for improved cooling in the
fillet regions of turbine guide members.
SUMMARY OF THE INVENTION
[0007] A turbine fluid guide member is described herein as
including: an airfoil portion; a platform portion; and a fillet
joining the airfoil portion to the platform portion. The turbine
fluid guide member also includes a coolant outlet positioned
remotely from the fillet such that a cooling flow exiting the
outlet is directed by a vortex flow to form a cooling film over the
fillet. In addition, the turbine fluid guide member may include a
plurality of holes formed in the airfoil directing a coolant flow
into a vortex flow to create a cooling film along a portion of the
fillet on the pressure side. The turbine fluid guide member may
also include another plurality of holes formed in the platform
directing the coolant flow into a vortex flow to create another
cooling film along a portion of the fillet on the suction side.
[0008] A combustion turbine engine is described herein as
including: a compressor; a turbine; a combustor; and a turbine
fluid guide member. The turbine fluid guide member also includes an
airfoil portion, a platform portion, a fillet joining the airfoil
portion to the platform portion, and a coolant outlet positioned
remotely from the fillet such that a cooling flow exiting the
outlet is directed by a vortex flow to form a cooling film over the
fillet.
[0009] A method for cooling a portion of a turbine fluid guide
member is described herein as including: identifying a vortex flow
around the turbine fluid guide member; and selectively positioning
a coolant outlet relative to the vortex flow such that a cooling
flow exiting the outlet is directed by the vortex flow to form a
cooling film over a fillet portion of the turbine fluid guide
member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] These and other advantages of the invention will be more
apparent from the following description in view of the drawings
that show:
[0011] FIG. 1 is a perspective view of a cut-away of several
turbine airfoil portions showing hot combustion fluid flow around
the airfoil portions as known in the art.
[0012] FIG. 2 is a perspective view of a cut-away turbine airfoil
portion with attached platform showing hot combustion fluid flow
around the airfoil portion and cooling flows exiting fillet cooling
holes in the airfoil portion.
[0013] FIG. 3 is a perspective view of a cut-away turbine airfoil
portion with attached platform showing hot combustion fluid flow
around the airfoil portion and cooling flows exiting fillet cooling
holes in the platform portion.
[0014] FIG. 4 is a functional diagram of a combustion turbine
engine having a turbine including a fluid guide member of the
current invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] FIG. 2 illustrates a cut away portion of a turbine fluid
guide member 10 having an airfoil portion 12, a platform portion 14
and a fillet 16 joining the airfoil portion 12 to the platform
portion 14. In one aspect of the invention, the airfoil portion 12
may be a stationary vane, and, in another aspect, the airfoil
portion 12 may be a rotating blade. For the purposes of this
invention, platform portion 14 is intended to refer to the
structure to which the airfoil portion 12 is mounted. For example,
in a rotating blade embodiment, the platform portion 14 can be a
platform, and in a stationary vane embodiment, the platform portion
14 can be the vane shroud.
[0016] As depicted in FIG. 2, a hot combustion fluid flow 26
flowing towards the airfoil portion 12, separates into suction side
vortex flow 24 flowing around the airfoil portion 12 on a suction
side 28 and a pressure side vortex flow 22 flowing around the
airfoil portion 12 on a pressure side 30. In addition, as depicted
in FIG. 1, another pressure side vortex flow 23 crosses from an
adjacent airfoil portion (not shown) and flows along the airfoil
portion 12 on the suction side 28. The pressure side vortex flow 23
may combine with the suction side vortex flow 24 to form a combined
vortex flow 25. Experimental tests and simulations performed using
computational fluid dynamic (CFD) analysis techniques can be used
to analyze and predict such vortex flows 22, 23, 24, 25 depending
on the airfoil portion 12 geometry and the spacing of airfoil
portions 12 in relation to other airfoil portions 12. CFD software
packages available from Fluent, Incorporated and AEA Engineering
Technologies, Incorporated, for example, are useful for such an
analysis. The vortex flows 22, 23, 24, 25 may take the form of
multiple vortices of varying strength starting at the leading edge
34 of the airfoil portion 12 and continuing along the fillet 16
downstream past the trailing edge 36 of the airfoil portion 12. The
pressure side vortex flow 22 may also have a radially directed
component 31 flowing downwardly against the airfoil portion 12
towards the platform portion 14, as it flows longitudinally along
the fillet 16 on the pressure side 30. On the suction side 28, the
combined vortex flow 23 may have a radially directed component 33
flowing upwardly from the platform portion 14 against the airfoil
portion 12 as it flows longitudinally along the fillet 16.
[0017] Advantageously, the present inventors have innovatively
recognized that by directing a cooling fluid flow 20 into the
vortex flows 22, 23, 24, 25 flowing adjacent to the fillet 16,
improved cooling of the fillet 16 can be provided. For example,
fillet cooling holes 18a-18f can be positioned in the airfoil
portion 12 on the pressure side 30 relative to the pressure side
vortex flow 22 so that cooling fluid flow 20 exiting the fillet
cooling holes 18a-18f is injected into the pressure side vortex
flow 22. As a result, the radial component 31 of the pressure side
vortex flow 22 acts to direct the cooling fluid flow 20 downwards
from the fillet cooling holes 18a-18f, towards the fillet 16,
before being directed downstream in a longitudinal direction along
the fillet 16. When the cooling fluid flow 20 from one hole, for
example 18a, ceases to effectively cool the fillet 16, another
fillet cooling hole, such as 18b, can be positioned to replenish
the cooling fluid flow 20. This process may be continued
longitudinally along the length of the airfoil portion, such as
near the fillet 16, to the trailing edge, providing a continuous
cooling fluid flow 20 to form a cooling film 32 over the fillet
16.
[0018] Accordingly, the inventors have realized that by controlling
geometric parameters of the fillet cooling holes 18a-18f, such as
location, orientation, angle with respect to an exit surface,
diameter, hole geometry, spacing, and pressure drop between a hole
inlet opening and exit opening, the holes 18a-18f can be configured
to inject cooling fluid 20 into the pressure side vortex flow 22 so
that a cooling film 32 is formed over the fillet 16, providing
improved cooling of the fillet 16 compared to conventional
techniques. It should be understood that the cooling hole positions
depicted in FIG. 1 are provided as example positions. Cooling holes
may be positioned anywhere along the length of the airfoil or
platform, including the leading and trailing edges of the airfoil,
provided that the position of the holes effectively couples cooling
fluid exiting the holes to a secondary vortex to direct the cooling
fluid to flow over the fillet to provide improved cooling of the
fillet. For example, fluid flow simulations, such as CFD
techniques, may be used to configure the shape, orientation, and
positioning of cooling holes for fillet cooling in a desired
airfoil geometry.
[0019] FIG. 3 is a perspective view of a turbine airfoil portion 46
showing hot combustion fluid flow around the airfoil portion 46 and
cooling flows exiting fillet cooling holes 54a-54d in the platform
40. In another aspect of the invention, fillet cooling holes
54a-54d may be formed in the platform portion 40 to direct a
cooling fluid flow 42 over the fillet 44. As is understood in the
art, the three dimensional geometry of the airfoil portion 46, in
combination with the attached platform portion 40, determines how
the hot combustion fluid flow 48 flows around the airfoil portion
46 and creates a suction side vortex flow 50. Therefore, depending
on the geometry of the airfoil portion 46, it may be beneficial to
position the fillet cooling holes 54a-54d in the platform portion
40, so that optimum coupling of a cooling fluid flow 42 into the
suction side vortex flow 50 and the combined vortex flow 51 for
film cooling of the fillet 44 is provided. For example, the
combined vortex flow 51 flowing adjacent to the fillet 44 on a
suction side 55 may have a radially directed component 53 directed
upwardly against the airfoil portion 46 from the platform portion
44.
[0020] By positioning fillet cooling holes 54a-54d in the platform
portion 40 relative to the combined vortex flow 51 so that cooling
fluid flow 42 exiting the fillet cooling holes 54a-54d is injected
into the combined vortex flow 51, the radially directed component
53 of the combined vortex flow 51 acts to direct the cooling fluid
flow 42 upwardly from the platform portion 40 towards the fillet 44
before being directed in a longitudinal direction downstream along
the fillet 44, thereby establishing a cooling film 52 over the
fillet 44. Similarly, fillet cooling holes (not shown) can be
formed in the platform portion 40 adjacent to the pressure side 56
of the airfoil portion 46 to inject the cooling fluid flow into a
pressure side vortex (not shown) flowing over the fillet 44 on the
pressure side 56 as described in relation to FIG. 1. In yet another
embodiment, fillet cooling holes may be formed in both the airfoil
portion 46 and the platform portion 40, or any combination thereof,
to provide optimum cooling of the fillet 44, depending on the
nature of vortices flowing adjacent to the fillet 44.
[0021] Optimal positioning of fillet cooling holes to provide
improved cooling of a fillet in a turbine fluid guide member will
now be described. With the advent of high power computing
capability, computation and simulation of fluid flows relative to
complex geometries has recently become possible using CFD analysis.
By taking advantage of the efficiencies offered by CFD analysis and
simulation, various parameters regarding position of fillet cooling
holes relative to secondary vortices can be analyzed to determine
optimal positioning of the holes. The placement and orientation of
the fillet cooling holes near the fillet is critical to the
invention, and depends upon the strength and orientation of a
secondary vortex flow flowing near the fillet cooling hole. If the
cooling fluid exiting the fillet cooling holes is not effectively
coupled to the secondary vortex, the cooling fluid may be directed
directly downstream when exiting the holes, instead of flowing over
the fillet before being directed downstream. If the vortex is too
strong in the area of the cooling hole, the cooling fluid may be
pulled past the fillet and form a cooling film over a different
area before being directed downstream. In addition, different
airfoil portion geometries will result in different vortex flows,
so that placement of fillet cooling holes in one airfoil portion
geometry may not be effective in a different airfoil portion
geometry.
[0022] Advantageously, CFD techniques can be used in an iterative
design approach to optimally configure the fillet cooling holes to
establish a cooling film over the fillet. Generally, the design
approach includes identifying a secondary vortex flow adjacent to
the fillet and selectively positioning holes relative to the vortex
flow, such that a cooling flow exiting the holes in an area remote
from the fillet is directed to form a cooling film over the fillet.
Using CFD techniques, a desired airfoil and platform geometry can
be created, for example, using computer aided drawing (CAD)
techniques, which can be transformed into a mesh, such as a finite
element mesh or finite volume mesh, to serve as a model for input
into the CFD software. Fillet cooling holes can be experimentally
positioned in the model where the holes are most likely to direct
the cooling fluid into an identified secondary vortex and over the
fillet, based on a general knowledge of fluid dynamics. Flow
conditions can then be simulated and various parameters of the
simulation, such as fluid particle trajectories or contours of
temperature, can be plotted with respect to the input geometry to
determine the effectiveness of the hole positions in providing a
cooling flow to the fillet. For example, a skilled artisan may use
CFD techniques and temperature gradient plots provided by CFD
simulations to determine the effectiveness of hole positioning for
fillet cooling. Multiple iterations of simulating, repositioning
fillet cooling holes in the model, and further simulating can be
performed to achieve optimal positioning of the holes to provide
cooling of the fillet.
[0023] FIG. 4 illustrates a combustion turbine engine 70 having a
compressor 72 for receiving a flow of filtered ambient air 74 and
for producing a flow of compressed air 76. The compressed air 76 is
mixed with a flow of a combustible fuel 80, such as natural gas or
fuel oil for example, provided by a fuel source 78, to create a
fuel-oxidizer mixture flow 82 prior to introduction into a
combustor 84. The fuel-oxidizer mixture flow 82 is combusted in the
combustor 84 to create a hot combustion gas 86.
[0024] A turbine 88, including a fluid guide member 92, receives
the hot combustion gas 86, where it is expanded to extract
mechanical shaft power. In an aspect of the invention, the fluid
guide member 92 fillet is cooled using the techniques of providing
fillet cooling holes coupled to secondary vortices as previously
described. In one embodiment, a common shaft 90 interconnects the
turbine 88 with the compressor 72, as well as an electrical
generator (not shown) to provide mechanical power for compressing
the ambient air 74 and for producing electrical power,
respectively. The expanded combustion gas 86 may be exhausted
directly to the atmosphere or it may be routed through additional
heat recovery systems (not shown).
[0025] While the preferred embodiments of the present invention
have been shown and described herein, it will be obvious that such
embodiments are provided by way of example only. Numerous
variations, changes and substitutions will occur to those of skill
in the art 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.
* * * * *