U.S. patent application number 10/244068 was filed with the patent office on 2004-03-18 for swirler assembly with improved vibrational response.
This patent application is currently assigned to Siemens Westinghouse Power Corporation. Invention is credited to Ohri, Rajeev, Parker, David M..
Application Number | 20040050058 10/244068 |
Document ID | / |
Family ID | 31946390 |
Filed Date | 2004-03-18 |
United States Patent
Application |
20040050058 |
Kind Code |
A1 |
Ohri, Rajeev ; et
al. |
March 18, 2004 |
SWIRLER ASSEMBLY WITH IMPROVED VIBRATIONAL RESPONSE
Abstract
A turbo machinery assembly, having a natural frequency outside
of the range of operational vibrational forces and further having
increased damping capability, comprises a turbo machinery component
and a plate having an elongated opening defining an inner surface.
The turbo machinery component has a first end and a second end; the
second end having an outer profile that extends inside the opening,
contacting portions of the inner surface and extending peripherally
to regions of clearance with the inner surface. The second end of
the turbo machinery component may also extend beyond the inner
surface. The turbo machinery component may further include a sleeve
having a proximal end and a distal end. The second end of the turbo
machinery component extends into the sleeve through the proximal
end. The distal end of the sleeve defines the second end of the
turbo machinery component extending inside the inner surface.
Inventors: |
Ohri, Rajeev; (Winter
Springs, FL) ; Parker, David M.; (Oviedo,
FL) |
Correspondence
Address: |
Siemenes Corporation
Intellectual Property Department
186 Wood Avenue South
Iselin
NJ
08830
US
|
Assignee: |
Siemens Westinghouse Power
Corporation
|
Family ID: |
31946390 |
Appl. No.: |
10/244068 |
Filed: |
September 13, 2002 |
Current U.S.
Class: |
60/748 |
Current CPC
Class: |
F23R 3/14 20130101 |
Class at
Publication: |
060/748 |
International
Class: |
F23R 003/14 |
Claims
What is claimed is:
1. A swirler assembly comprising: a swirler having an inlet end and
an outlet end; a sleeve having a proximal end and a distal end,
wherein said outlet end of said swirler extends into said sleeve
through said proximal end; a plate having an opening, said opening
defining an inner annular surface; wherein said distal end of said
sleeve extends into said opening and contacts at least a portion of
said inner annular surface, whereby said swirler assembly has a
natural frequency outside of the range of operational vibrational
forces in a combustor and further having enhanced damping
characteristics.
2. The swirler assembly according to claim 1, wherein said inner
annular surface is elliptical, defining a minor axis and a longer
major axis transverse to the minor axis.
3. The swirler assembly according to claim 2, wherein said distal
end contacts said inner annular surface substantially at points
along said minor axis and transitions to a clearance from said
annular surface substantially at points along said major axis.
4. The swirler assembly according to claim 3, wherein said sleeve
contacts said inner annular surface along approximately 70 percent
of said inner annular surface.
5. The swirler assembly according to claim 4, wherein said
clearance ranges from approximately 0 to approximately 3 mils.
6. The swirler assembly according to claim 3, wherein said swirler
comprises a sole support pin extending from said swirler.
7. The swirler assembly according to claim 6, wherein said support
pin is cast as part of said swirler.
8. The swirler assembly according to claim 1, wherein said sleeve
extends axially past said inner annular surface.
9. The swirler assembly according to claim 1, wherein said plate
defines a profile transitioning from a planar face through a convex
fillet to said inner annular surface, said sleeve having a tapering
profile such that the sleeve profile substantially follows the
convex fillet and inner annular surface profile in shape.
10. The swirler assembly of claim 1, wherein said sleeve is
circumferentially welded to said swirler.
11. The swirler assembly of claim 1, wherein said sleeve is divided
into a first half and a second half; said first half including said
proximal end and a first joining end, said second half including a
second joining end and said distal end, said joining ends being
circumferentially welded together.
12. A turbo machinery assembly comprising: a turbo machinery
component having a first end and a second end; said second end
having an outer profile; a plate having an elongated opening, said
elongated opening defining an inner surface; wherein said outer
profile of said second end of said turbo machinery component
extends inside said opening and contacts portions of said inner
surface and extends peripherally to regions of clearance with said
inner surface; and whereby said turbo machinery assembly has a
natural frequency outside of the range of operational vibrational
forces and further has increased damping capability.
13. The turbo machinery assembly of claim 12, wherein said second
end of said turbo machinery component further extends beyond said
inner surface.
14. The turbo machinery assembly according to claim 12, wherein
said inner surface is generally annular.
15. The turbo machinery assembly of claim 12, wherein said turbo
machinery component includes a sleeve having a proximal end and a
distal end, wherein said turbo machinery component extends into
said sleeve through said proximal end, and wherein said distal end
of said sleeve defines said second end of said turbo machinery
component extending inside said inner surface.
16. A swirler assembly, comprising: a swirler having an inlet end
and an outlet end and a plurality of swirler vanes therebetween; a
sleeve having a proximal end and a distal end, wherein said outlet
end of said swirler extends into said sleeve through said proximal
end and is secured to said sleeve by welding; a plate having a
profile of a planar face transitioning through a convex fillet to
an elliptical opening, said elliptical opening defining an inner
elliptical annular surface defining a minor axis and a longer major
axis transverse to said minor axis; wherein said sleeve has a
tapering profile from a first diameter proximate said swirler weld
to said distal end, said tapering profile including a concave taper
substantially following the convex fillet of said plate and
transitioning to a straight profile substantially following said
inner annular surface; and said sleeve extending into said opening
and contacting said plate at said convex fillet and said inner
annular surface at points along said minor axis and transitioning
to a clearance with said inner annular surface and said convex
fillet at points along said major axis, wherein at least
approximately 50% of said inner annular surface is contacted and
the clearance is less than approximately 3 mils, whereby said
swirler assembly has a natural frequency outside of the range of
operational vibrational forces in a combustor and further having
enhanced damping characteristics, and said clearance permits
thermal expansion of said sleeve.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] (Not Applicable)
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] (Not Applicable)
FIELD OF THE INVENTION
[0003] The present invention relates in general to gas turbines
and, more particularly, to swirler assemblies.
BACKGROUND OF THE INVENTION
[0004] Gas turbines generally comprise the following elements: a
compressor for compressing air; a combustor for producing a hot gas
by burning fuel in the presence of the compressed air produced by
the compressor; and a turbine for expanding the hot gas produced by
the combustor.
[0005] As shown in FIG. 1, an example of a prior art gas turbine
combustor 10 comprises a nozzle housing 12 having a nozzle housing
base 14. A diffusion fuel pilot nozzle 16, having a pilot fuel
injection port 18, extends through nozzle housing 12 and is
attached to nozzle housing base 14. In the shown configuration,
main fuel nozzles 20, each having at least one main fuel injection
port 22, extend substantially parallel to pilot nozzle 16 through
nozzle housing 12 and are attached to nozzle housing base 14. Fuel
inlets 24 provide fuel 26 to main fuel nozzles 20. A main
combustion zone 28 is formed within a liner 30. A pilot cone 32,
having a diverged end 34, projects from the vicinity of pilot fuel
injection port 18 of pilot nozzle 16. Diverged end 34 is downstream
of main fuel swirlers 36. A pilot flame zone 38 is formed within
pilot cone 32 adjacent to main combustion zone 28.
[0006] Compressed air 40 from compressor 42 flows between support
ribs 44 through main fuel swirlers 36. Each main fuel swirler 36 is
substantially parallel to pilot nozzle 16 and adjacent to main
combustion zone 28. Within each main fuel swirler 36, a plurality
of swirler vanes 46 generate air turbulence upstream of main fuel
injection ports 22 to mix compressed air 40 with fuel 26 to form a
fuel/air mixture 48. Fuel/air mixture 48 is carried into main
combustion zone 28 where it combusts. Compressed air 50 enters
pilot flame zone 38 through a set of stationary turning vanes 52
located inside pilot swirler 54. Compressed air 50 mixes with pilot
fuel 56 within pilot cone 32 and is carried into pilot flame zone
38 where it combusts.
[0007] FIG. 2 shows a detailed view of an exemplary prior art fuel
swirler 36. As shown in FIG. 2, fuel swirler 36 is substantially
cylindrical in shape, having a flared inlet end 58 and a tapered
outlet end 60. A plurality of swirler vanes 46 are disposed
circumferentially around the inner perimeter 62 of fuel swirler 36
proximate flared end 58. In the shown configuration, fuel swirler
36 surrounds main fuel nozzle 20 proximate main fuel injection
ports 22. Fuel swirler 36 is positioned with swirler vanes 46
upstream of main fuel injection ports 22 and tapered end 60
adjacent to main combustion zone 28. Flared inlet end 58 is adapted
to receive compressed air 40 and channel it into fuel swirler 36.
Tapered outlet end 60 is adapted to fit into sleeve 64. Swirler
vanes 46 are attached to a hub 66. Hub 66 surrounds main fuel
nozzle 20.
[0008] FIG. 3 shows an upstream view of combustor 10. Pilot nozzle
16 is surrounded by pilot swirler 54. Pilot swirler 54 has a
plurality of stationary turning vanes 52. Pilot nozzle 16 is
surrounded by a plurality of main fuel nozzles 20. A main fuel
swirler 36 surrounds each main fuel nozzle 20. Each main fuel
swirler 36 has a plurality of swirler vanes 46. The diverged end 34
of pilot cone 32 forms an annulus 68 with liner 30. Main fuel
swirlers 36 are upstream of diverged end 34. Fuel/air mixture 48
flows through annulus 68 (out of the page) into main combustion
zone 28 (not shown in FIG. 3).
[0009] Fuel swirler 36 is attached to liner 30 via attachments 70
and swirler base 72. With respect to the latter manner of
attachment, the distal end of sleeve 74 is adjacent to the swirler
base plate 72 as shown in FIG. 2. The distal end of sleeve 74 and
the base plate 72 typically do not come into contact and are
actually spaced approximately 10 mils apart. FIG. 3 shows a
circular array of six swirlers, but other quantities, such as a
series of eight swirlers, can be employed.
[0010] The other manner of attaching the swirler 36 to liner 30 is
by way of attachments 70. In initial designs, attachments 70
comprised dual straight pins, each pin being welded at one end to
liner 30 and at the other end to the swirler 36. This design,
however, often fails due to fatigue induced cracking of the pins at
the support casing. One prior design revision includes replacing
the straight pin attachments with hourglass-shaped pins (as shown)
to provide improved weld areas on both the swirler 36 and the liner
30. However, this design also suffers from fatigue-related
failures, primarily occurring at the weld joint between the
hourglass-shaped pin attachments 70 and the swirler 36.
[0011] The fatigue failures stem from a swirler's exposure to
vibrational forces generated during combustor operation. Combustion
dynamics typically range from approximately 110-150 Hz, although
variations outside this range are possible depending on the system
design. Prior swirlers, when only adjacent to or abutting the base
plate, generally had a natural frequency of approximately 145 Hz,
falling within the typical vibrational range experienced during
combustion dynamics. Consequently, when a swirler is subjected to
such forces, the swirler will resonate, and repeated resonance of
the swirler ultimately fatigues the weld joints of the support
pins.
[0012] Thus, high cycle fatigue failures are a recurring problem
with respect to swirlers and other turbo machinery components. The
problem has been exacerbated by combustion design changes to reduce
emissions and increase efficiency. These design changes have
increased the severity of the combustion dynamics, requiring more
robust swirler assemblies. Therefore, there is a continuing need
for a swirler assembly that can avoid vibration-induced resonance
and that can further enhance the inherent damping characteristics
of the swirler to constrain any vibratory motion.
SUMMARY OF THE INVENTION
[0013] It is an object of the invention to provide a swirler
assembly that is adapted to tolerate the severity of the dynamics
of combustors designed for reduced emissions and greater
efficiencies.
[0014] It is another object of the invention to provide a more
robust swirler assembly that can accommodate changes due to thermal
expansion.
[0015] These and other objects of the invention are achieved by a
swirler assembly adapted to interface with a supporting base plate
so as to raise the resonant frequency of the swirler assembly above
the vibrational range of the combustion environment and to increase
the damping of the swirler response to the combustion dynamics. The
present invention applies particularly to a swirler assembly that
includes a swirler, a generally cylindrical swirler sleeve and a
plate. The swirler has an inlet and an outlet end. The sleeve has a
proximal end and a distal end. The outlet end of the swirler
extends into the sleeve through the proximal end. The plate has an
opening that, due to manufacturing processes, is elongated into an
elliptical shape.
[0016] According one aspect of the invention, the distal end of the
sleeve extends into the plate opening and contacts the inner
ring-like surface of the plate opening at least partially around
its periphery so that portions of the sleeve contact the surface
along the minor axis of the elliptical opening and transition to a
clearance along the major axis. The contact areas between the
sleeve and the plate stiffen the interface and increase the natural
frequency of the swirler. For example, the natural frequency can be
increased to 700 Hz, well above the operational combustion
dynamics, in the neighborhood of 110-150 Hz. The contact areas also
increase frictional forces to damp the vibrational response of the
swirler.
[0017] The sleeve preferably tapers from a larger diameter outside
the plate opening down to the diameter of the portion that extends
into, and preferably through, the opening. The shape of the taper
preferably substantially follows the profile of the plate into the
opening. The matching profile increases the areas of contact
between the sleeve and the plate, increasing the stiffness and the
surface area for generating frictional damping forces.
[0018] The clearance in the region of the major axis of the
elliptical plate opening accommodates thermal stresses that can
arise from expansion of the sleeve in the high temperature
environment of the combustor. Thus, the swirler assembly according
to aspects of the invention avoids resonance and damps vibrational
responses while providing for thermal expansion.
[0019] In another aspect, a turbo machinery assembly includes a
turbo machinery component and a plate having an opening. The
opening defines an inner surface. The turbo machinery component has
a first end and a second end. The second end of the turbo machinery
component has an outer profile that substantially follows the inner
surface and substantially adjacent to at least a portion of the
plate surrounding the opening. The outer profile contacts a portion
of the inner surface while providing clearance in other regions
along the opening periphery. The turbo machinery assembly has a
natural frequency outside of the range of operational vibrational
forces and further has increased damping capability.
[0020] In still another aspect, the present invention is directed
to a method for altering the natural frequency and enhancing the
damping characteristics of a swirler. The method includes the steps
of: providing a plate having an opening, which defines an inner
surface; providing a swirler having an inlet end and an outlet end;
providing a sleeve having a first end and a second end, the second
end having an outer surface substantially conforming to the inner
annular surface and to a portion of the plate surrounding the
opening; placing the outlet end of the swirler into a first end of
a sleeve; and placing the second end of the sleeve into the opening
such that the second end of the sleeve substantially contacts a
portion of the inner surface of the opening and adjacent to the
opening while providing clearance in other regions of the opening
periphery.
[0021] In a further aspect of the invention, the stabilization
provided by the sleeve engagement with the base plate can permit
the use of a single pin for supporting the swirler from the
surrounding shell. The single pin can be cast, providing further
manufacturing savings.
[0022] Thus, the invention provides a swirler assembly that can
more readily endure combustion dynamics and high temperature
conditions while presenting opportunities for manufacturing
economies.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a cross-sectional view of a prior art gas turbine
combustor.
[0024] FIG. 2 is a cross-sectional view of a prior art main fuel
swirler.
[0025] FIG. 3 is an upstream view of a prior art gas turbine
combustor.
[0026] FIG. 4 is a cross-sectional view a preferred embodiment of a
swirler according to the present invention.
[0027] FIG. 5 is close-up view of FIG. 4, showing the engagement of
the swirler and the base plate according to the present
invention.
[0028] FIG. 6 is a sectional view taken along section line 6-6 in
FIG. 5, showing the fit of the swirler sleeve into an elliptical
opening of the base plate, exaggerated for clarity of
illustration.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0029] The present invention provides a more vibrationally tolerant
swirler assembly and a method for making such a swirler assembly
that has a natural frequency outside of the range of
combustion-generated vibrational forces to preventing swirler
resonance. In addition, the swirler according to aspects of the
invention enhances the damping capability of the swirler assembly
so as to subdue any vibrational forces acting on the system. The
invention has application to various turbo machinery components.
Features of the invention are, however, described with respect to
fuel swirlers for use in a turbine combustor.
[0030] An embodiment of the swirler assembly 80 of the present
invention is illustrated in FIGS. 4 and 5. In FIG. 4, an exemplary
swirler 82 is shown, but the structure is not limited to swirlers
and can actually be any turbo machinery component having first and
second ends. Moreover, the swirler is not limited to any particular
configuration, but it will generally have an inlet end 84 and an
outlet end 86. Preferably, the swirler 82 is generally cylindrical
in shape, but the swirler may be any shape, such as rectangular or
polygonal, as dictated by design considerations and performance
requirements. In the shown embodiment, the swirler tapers from its
flared inlet end 84 to its outlet end 86. Like the other features
of the swirler, the outer surface does not have to be tapered. For
example, the swirler may have a generally uniform cross-sectional
profile along its length.
[0031] The swirler 82 is supported by one or more pins 88, which
can be welded to the swirler 82 at one end and welded or otherwise
secured to a combustor outer liner (not shown, see FIG. 5). The
pins 88 can be hour-glass shaped in profile to provide expanded
welding footprints, as is known in the art.
[0032] Preferably, the swirler assembly 80 includes a sleeve 90
having a proximal end 92 and distal end 94. The sleeve 90 is
preferably cylindrical in shape. However, the sleeve 90 need not be
limited to a cylindrical configuration. The sleeve 90 can be made
of stainless steel.
[0033] The outlet end 86 of the swirler 82 is positioned so as to
extend into the proximal end 92 of the sleeve 90. Once the swirler
82 is positioned inside of the sleeve 90, the sleeve 90 and swirler
82 are welded 96 together, preferably peripherally or
circumferentially in the case of a cylindrical swirler. The sleeve
90 may be a single cast component or it may be divided into first
and second halves (not shown), with first half including a proximal
end and a first joining end, and second half including a second
joining end and a distal end, the joining ends abutted and welded
circumferentially.
[0034] According to aspects of the invention, the sleeve decreases
in diameter (or periphery) from its proximal end 92 to its distal
end 94. Beginning at its proximal end 92, the sleeve 90 generally
tapers until an area of greater thickness 96 is reached. In this
area, the outer surface of the sleeve is substantially horizontal
but then a second, sharper taper begins 98. This tapered 98 region
can be curved instead of being linearly tapered. Eventually the
taper or curve 98 transitions into a second substantially
horizontal portion 99 which continues until the extreme distal end
94 of the sleeve 90 is reached.
[0035] Referring to FIG. 5, a base plate 100 supports the swirler
assembly 80 and attaches the swirler assembly 80 to the outer liner
102. Commonly, the plate is made of an alloy, for example,
Hastelloy X. The plate 100 is generally disposed between the
swirler 82 and the combustion chamber 104. The plate 100 can be
anchored to the outer liner 102 by welds 106. The plate 100 may be
a single component such as a flat plate, or it may be a localized
area of a larger structure.
[0036] An opening 108 is provided in the plate. The opening 108 may
be a through hole or it may be, as shown, a product of bends in the
plate 100. Typically, the plate 100 is shaped from a metal sheet
and the openings are drawn out from the sheet. The plate is welded
in place to the liner. The manufacturing processes often result in
an elongation of the plate opening 108 to a generally vertical
elliptical shape, as discussed more fully below.
[0037] The opening 108 is defined by a ring-like inner surface 110
that is connected to the generally vertical face 112 of the plate
100 by a convex fillet region 114. As used in this specification,
the inner surface 110 is referred to as annular to describe the
generally ring-like shaped of the surface. This terminology is not
intended to connote that the surface is circular, when the shaped
is more generally elliptical due to the elongation that occurs
during manufacture.
[0038] According to the invention, the distal end 94 of the sleeve
90 extends into the opening 108, and preferably extends through and
past the annular surface 110 of the opening 108. The second taper
98 is shaped to substantially follow the convex fillet 114 and the
second substantially horizontal portion 99 substantially follows
the inner annular surface 110 of the opening 108.
[0039] FIG. 6 shows a cross section of the swirler sleeve distal
end 94 as inserted in the opening 108 of the base plate 100. The
sleeve 90 engages the inner surface 110 of the base plate opening
108 along the minor axis 116 of the ellipse and transitions to a
clearance fit 118 at along the major axis 120. In this example, the
major axis 120 of the elliptical opening 108 extends substantially
through the top and bottom of the opening while the minor axis
extends across the left and right sides. This orientation
corresponds to the general tendency of the base plate opening 108
to elongate vertically during manufacture. The orientation can of
course deviate from this example.
[0040] The degree of elongation and the percentage of the inner
surface 110 that is contacted can vary. With tolerances of the
preferably circular sleeve to an average of the elliptical
dimensions, the percentage of surface contact is preferably around
70%.
[0041] The clearance 118 in the region of the elliptical major axis
120 is preferably in the range of 0-3 mils. The resonant frequency
is directly related to the percentage of contact and inversely
related the degree of clearance. Further, the clearance region 118
allows for thermal expansion of the sleeve 90, thus reducing
thermal stresses in the high temperature environment of a turbine
combustor.
[0042] Referring again to FIG. 5, the area of contact not only
serves to increase the resonant frequency outside the range of
combustion dynamics, but also generates frictional forces that damp
the vibrational response of the swirler. The areas of friction are
further increased by the taper 98 of the sleeve 90 that
substantially mimics the convex fillet 114 of the plate 100. In the
regions of contact of the inner surface 110, there can be a
corresponding contact along the convex fillet region 114.
[0043] With the increase stability provided by the nested sleeve,
the swirler can be supported by a single pin 88, located generally
centrally, instead of a pair of spaced pins. Moreover, the pins 88
can be cast as hollow members with the rest of the cast swirler,
and increased in diameter to maintain proper strength in view of
its hollow interior (not shown).
[0044] The pin 88, whether a single or a pair can be reinforced at
its junction with the swirler main body 82. One approach is to
thicken the body in the region of the pin.
[0045] The preferred embodiment of the swirler assembly 80 employs
a sleeve 90. Of course, a sleeve 90 may not be necessary in the
assembly so long as the outlet end 86 of the swirler 82 or other
turbo machinery component substantially follows the opening 108 in
the plate 100 and substantially adjacent to a portion of the plate
surrounding the opening to provide a hybrid contact and clearance
fit with the surfaces in and around the opening.
[0046] The present invention is also directed to a method for
altering the natural frequency and enhancing the damping
characteristics of a swirler. Steps include, in no particular
order, providing a plate 100 having an opening 108 that defines an
inner annular surface 110; providing a swirler 82 having inlet 84
and outlet 86 ends; and providing a sleeve 90 having first 92 and
second 94 ends. The second end 94 of the sleeve 90 has an outer
surface substantially conforming to the inner annular surface 110
of the opening 108 and also to a portion of the plate 100
surrounding the opening 214 such that contact occurs in certain
regions while other regions are spaced. The outlet end 86 of the
swirler 82 is placed into the first end 92 of the sleeve 90.
Additionally, the swirler 82 may be secured to the sleeve 90 by,
for example, welding. The second end 94 of the sleeve 90 is
substantially matingly fitted into and at least partially beyond
the inner annular surface 110 of the opening 108 and substantially
adjacent to a portion of the plate 100 surrounding the opening
108.
[0047] In operation, the swirler assembly 80 described above has a
natural frequency out of the range of commonly experienced
combustion dynamic vibrational forces. As noted earlier, combustion
dynamics typically range from approximately 110 Hz to 150 Hz. Tests
on a swirler assembly according to principles of the present
invention reveal a natural frequency as high as approximately 700
Hz. The increased natural frequency can vary as a function of the
percent of the swirler sleeve in contact with the inner surface of
the base plate opening and the amount of clearance in the areas of
separation, but the resonant frequency is nevertheless well above
the operational frequency range of the combustion environment.
Accordingly, the combustion dynamic vibration will not cause the
swirler to resonate and ultimately cause some part or connection to
fail due to fatigue. The surface areas of contact generate
frictional forces to damp the vibrational response of the swirler,
and the clearance regions permit the arrangement to thermally
expand.
[0048] It will of course be understood that the invention is not
limited to the specific details described herein, which are given
by way of example only, and that various modifications and
alterations are possible within the scope of the invention as
defined in the appended claims.
* * * * *