U.S. patent application number 12/418875 was filed with the patent office on 2009-10-15 for repairable fuel nozzle.
Invention is credited to Michael A. Benjamin, Alfred Mancini, Marie Ann McMasters.
Application Number | 20090256007 12/418875 |
Document ID | / |
Family ID | 41162795 |
Filed Date | 2009-10-15 |
United States Patent
Application |
20090256007 |
Kind Code |
A1 |
McMasters; Marie Ann ; et
al. |
October 15, 2009 |
REPAIRABLE FUEL NOZZLE
Abstract
A repairable fuel nozzle is disclosed, comprising an adaptor
configured to direct a fuel flow from at least one flow passage in
a fuel distributor to a pilot assembly comprising a fuel
swirler.
Inventors: |
McMasters; Marie Ann;
(Mason, OH) ; Benjamin; Michael A.; (Cincinnati,
OH) ; Mancini; Alfred; (Cincinnati, OH) |
Correspondence
Address: |
GENERAL ELECTRIC COMPANY
GE AVIATION, ONE NEUMANN WAY MD H17
CINCINNATI
OH
45215
US
|
Family ID: |
41162795 |
Appl. No.: |
12/418875 |
Filed: |
April 6, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61044116 |
Apr 11, 2008 |
|
|
|
Current U.S.
Class: |
239/463 ;
239/589 |
Current CPC
Class: |
F23R 2900/00018
20130101; F23R 3/28 20130101; F23R 3/286 20130101; Y10T 29/49746
20150115; Y02T 50/675 20130101; F23R 3/343 20130101; F23R 3/283
20130101; Y10T 29/49318 20150115; B23P 6/005 20130101; F23D
2900/14701 20130101; F23R 3/14 20130101; Y10T 29/4932 20150115;
Y10T 137/265 20150401; B22F 2007/068 20130101; F23D 2900/00018
20130101; B23P 6/007 20130101; F23D 2213/00 20130101; Y02T 50/60
20130101; B23P 2700/13 20130101; B33Y 80/00 20141201 |
Class at
Publication: |
239/463 ;
239/589 |
International
Class: |
B05B 1/34 20060101
B05B001/34; F23D 11/38 20060101 F23D011/38 |
Claims
1. A repairable fuel nozzle comprising: an adaptor configured to
direct a fuel flow from at least one flow passage in a fuel
distributor to a pilot assembly comprising a fuel swirler.
2. A repairable fuel nozzle according to claim 1 wherein the
adaptor is coupled to the fuel distributor.
3. A repairable fuel nozzle according to claim 2 wherein the
adaptor is coupled to the fuel distributor by brazing.
4. A repairable fuel nozzle according to claim 1 wherein the
adaptor is coupled to the pilot assembly.
5. A repairable fuel nozzle according to claim 4 wherein the
adaptor is coupled to the pilot assembly by brazing.
6. A repairable fuel nozzle according to claim 1 wherein the
adaptor is configured to direct a fuel flow from two flow passages
in the fuel distributor to a pilot assembly comprising two pilot
flow orifices.
7. A repairable fuel nozzle according to claim 1 wherein the fuel
distributor is made using a rapid manufacturing process.
8. A repairable fuel nozzle according to claim 7 wherein the rapid
manufacturing process is a laser sintering process.
9. A repairable fuel nozzle according to claim 1 further comprising
an air swirler having a plurality of vanes.
10. A repairable fuel nozzle according to claim 9 wherein the pilot
assembly is located radially inward in the swirler.
11. A repairable fuel nozzle comprising: a pilot assembly
comprising a fuel swirler and at least one opening for ejecting a
fuel therethrough located in a primary orifice, wherein the pilot
assembly is configured to be capable of being coupled to the fuel
nozzle during a repair of the fuel nozzle.
12. A repairable fuel nozzle according to claim 11 wherein the
pilot assembly comprises an annular primary orifice located
substantially coaxially with an annular secondary orifice.
13. A repairable fuel nozzle according to claim 12 wherein the
annular secondary orifice comprises an inner-step on a radially
inner side to locate the primary orifice within the secondary
orifice.
14. A repairable fuel nozzle according to claim 11 wherein the
pilot assembly is located radially inboard in an air swirler.
15. A repairable fuel nozzle according to claim 11 wherein the air
swirler is made using a rapid manufacturing process.
16. A repairable fuel nozzle according to claim 15 wherein the
rapid manufacturing process is a laser sintering process.
17. A repairable fuel nozzle according to claim 11 wherein the
pilot assembly comprises an outer-step on a radially outer side to
locate the pilot assembly within fuel nozzle during assembly.
18. A repairable fuel nozzle according to claim 11 wherein the
pilot assembly is coupled to a fuel distributor in the fuel
nozzle.
19. A repairable fuel nozzle according to claim 12 wherein the
pilot assembly is coupled to a fuel distributor by brazing.
20. A repairable fuel nozzle according to claim 11 wherein the
pilot assembly is in flow communication with a fuel distributor and
an adaptor in the fuel nozzle.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This Application claims priority to U.S. Provisional
Application Ser. No. 61/044,116, filed Apr. 11, 2008, which is
herein incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to fuel nozzles used in gas
turbine engines, and more specifically to repairable fuel nozzles,
components and methods of repairing fuel nozzle components and
assemblies.
[0003] Turbine engines typically include a plurality of fuel
nozzles for supplying fuel to the combustor in the engine. The fuel
is introduced at the front end of a burner in a highly atomized
spray from a fuel nozzle. Compressed air flows around the fuel
nozzle and mixes with the fuel to form a fuel-air mixture, which is
ignited by the burner. Because of limited fuel pressure
availability and a wide range of required fuel flow, many fuel
injectors include pilot and main nozzles, with only the pilot
nozzles being used during start-up, and both nozzles being used
during higher power operation. The flow to the main nozzles is
reduced or stopped during start-up and lower power operation. Such
injectors can be more efficient and cleaner-burning than single
nozzle fuel injectors, as the fuel flow can be more accurately
controlled and the fuel spray more accurately directed for the
particular combustor requirement. The pilot and main nozzles can be
contained within the same nozzle assembly or can be supported in
separate nozzle assemblies. These dual nozzle fuel injectors can
also be constructed to allow further control of the fuel for dual
combustors, providing even greater fuel efficiency and reduction of
harmful emissions. The temperature of the ignited fuel-air mixture
can reach an excess of 3500.degree. F. (1920.degree. C.). It is
therefore important that the fuel supply conduits, flow passages
and distribution systems are substantially leak free and are
protected from the flames and heat.
[0004] Over time, continued exposure to high temperatures during
turbine engine operations may induce thermal gradients and stresses
in the conduits and fuel nozzle components which may damage the
conduits or fuel nozzle components and may adversely affect the
operation of the fuel nozzle. For example, thermal gradients may
cause fuel flow reductions in the conduits and may lead to
excessive fuel maldistribution within the turbine engine. Exposure
of fuel flowing through the conduits and orifices in a fuel nozzle
to high temperatures may lead to coking of the fuel and lead to
blockages and non-uniform flow. To provide low emissions, modern
fuel nozzles require numerous, complicated internal air and fuel
circuits to create multiple, separate flame zones. Fuel circuits
may require heat shields from the internal air to prevent coking,
and certain fuel nozzle components may have to be cooled and
shielded from combustion gases. Additional features may have to be
provided in the fuel nozzle components to promote heat transfer and
cooling. Furthermore, over time, continued operation with damaged
fuel nozzles may result in decreased turbine efficiency, turbine
component distress, and/or reduced engine exhaust gas temperature
margin.
[0005] Improving the life cycle of fuel nozzles installed within
the turbine engine may extend the longevity of the turbine engine.
Known fuel nozzles include a delivery system, a mixing system, and
a support system. The delivery system comprising conduits for
transporting fluids delivers fuel to the turbine engine and is
supported, and is shielded within the turbine engine, by the
support system. More specifically, known support systems surround
the delivery system, and as such are subjected to higher
temperatures and have higher operating temperatures than delivery
systems which are cooled by fluid flowing through the fuel nozzle.
It may be possible to reduce the thermal stresses in the conduits
and fuel nozzles by configuring their external and internal
contours and thicknesses. Some known conventional fuel nozzles have
22 braze joints and 3 weld joints. Assembling and repairing such
conventional fuel nozzles is time consuming, difficult and
expensive.
[0006] Conventional gas turbine engine components such as, for
example, fuel nozzles and their associated swirlers, conduits,
distribution systems, venturis and mixing systems are generally
expensive to fabricate and/or repair because the conventional fuel
nozzle designs having complex swirlers, conduits and distribution
circuits and venturis for transporting, distributing and mixing
fuel with air include a complex assembly and joining of more than
thirty components. More specifically, the use of braze joints can
increase the time needed to fabricate such components and can also
complicate the fabrication process for any of several reasons,
including: the need for an adequate region to allow for braze alloy
placement; the need for minimizing unwanted braze alloy flow; the
need for an acceptable inspection technique to verify braze
quality; and, the necessity of having several braze alloys
available in order to prevent the re-melting of previous braze
joints. Moreover, numerous braze joints may result in several braze
runs, which may weaken the parent material of the component. Modern
fuel nozzles such as the Twin Annular Pre Swirl (TAPS) nozzles have
numerous components and braze joints in a tight envelope. The
presence of numerous braze joints can undesirably increase the
weight and the cost of repairing, assembling and inspection of the
components and assemblies.
[0007] Repair of a damaged conventional fuel nozzle is usually
difficult, involving disassembly of the fuel nozzle assembly
components to remove the damaged component. Fuel nozzle assemblies
usually have a number of braze joints and weld joints. A damaged
fuel nozzle component, such as a heat shield, is conventionally
repaired by welding excess metal into the damaged area and
machining the metal to form the appropriate shape, or by cutting
out the damaged area and replacing the cut out material by welding
or bracing a new piece of material into the damaged area. However,
such an approach is both expensive and results in reduced
performance by introducing undesirable steps in the fuel wetted
areas of nozzle component such as a venturi. Other known
manufacturing methods such as laser cladding often result in
imperfections and inclusions in the formed or repaired part
resulting from incomplete fusion of the melted layers to the
underlying substrate or previously welded material. These
imperfections and inclusions are often associated with complex
geometry of the formed or repaired part.
[0008] Accordingly, it would be desirable to have a repairable fuel
nozzle having features for protecting the structures from heat for
reducing undesirable effects from thermal exposure described
earlier. It is desirable to have a repairable fuel nozzle assembly
having features to reduce the cost and for ease of repair and
re-assembly as well as providing protection from adverse thermal
environment and for reducing potential leakage.
[0009] It is desirable to have a method of repair of components
having complex three-dimensional geometries, such as, for example,
a venturi with a heat shield, for use in repairable fuel nozzles
having reduced potential for leakage in a gas turbine engine. It is
desirable to have a method of repairing a component without having
to disassemble the component from a fuel nozzle assembly. It is
desirable to have a repair method that is economical and
flexible.
BRIEF DESCRIPTION OF THE INVENTION
[0010] The above-mentioned need or needs may be met by exemplary
embodiments which provide a repairable fuel nozzle comprising an
adaptor configured to direct a fuel flow from at least one flow
passage in a fuel distributor to a pilot assembly comprising a fuel
swirler.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The subject matter which is regarded as the invention is
particularly pointed out and distinctly claimed in the concluding
part of the specification. The invention, however, may be best
understood by reference to the following description taken in
conjunction with the accompanying drawing figures in which:
[0012] FIG. 1 is a partial cross-sectional view of exemplary
repairable fuel nozzle according to an exemplary embodiment of the
present invention.
[0013] FIG. 2 is an axial cross sectional view of the tip region of
the exemplary repairable fuel nozzle shown in FIG. 1.
[0014] FIG. 3 is a flow chart showing an exemplary embodiment of a
method for fabricating a unitary component according to an aspect
of the present invention.
[0015] FIG. 4 is a flow chart showing an exemplary embodiment of an
aspect of the present invention of a method of repairing a fuel
nozzle.
[0016] FIG. 5 an axial cross-sectional view of the tip region of an
exemplary fuel nozzle with some components drilled out.
[0017] FIG. 6 is a top plan view of an exemplary fuel swirler
having a braze-groove.
[0018] FIG. 7 is an axial cross-sectional view of an exemplary
primary pilot assembly.
[0019] FIG. 8 is an axial cross-sectional view of an exemplary new
pilot assembly placed on a test fixture for flow testing.
[0020] FIG. 9 is a schematic view of an X-ray inspection of a new
pilot assembly.
[0021] FIG. 10 is a schematic view of assembling a braze wire in
braze-groove in a new pilot assembly.
[0022] FIG. 11 is an axial cross-sectional view of the tip region
of an exemplary fuel nozzle during reassembly as part of
repair.
[0023] FIG. 12 is an axial cross sectional view of an exemplary
primary adaptor and braze wires.
[0024] FIG. 13 is an axial cross-sectional view of the tip region
of an exemplary fuel nozzle during reassembly as part of
repair.
[0025] FIG. 14 is an axial cross-sectional view of the tip region
of an exemplary fuel nozzle after repair.
[0026] FIG. 15 is an isometric view of an exemplary venturi having
exemplary damage.
[0027] FIG. 16 is a flow chart showing an exemplary method of
repairing a damaged heat-shield.
[0028] FIG. 17 is a side view of a damaged venturi with a partial
cross-sectional view of a damaged portion of the heat-shield
removed from the venturi.
[0029] FIG. 18 is a side view of a damaged venturi heat-shield
being repaired by an exemplary method of the present invention.
[0030] FIG. 19 is a side view of a damaged venturi heat-shield
being repaired in a radial direction by an exemplary method of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] A gas turbine engine has a combustion chamber housed within
an engine outer casing. Fuel is supplied into the combustion
chamber by fuel nozzles, such as for example shown in FIGS. 1 and
2. Liquid fuel is transported through conduits 80 within a stem 83,
such as, for example, shown in FIG. 1, to the fuel nozzle tip
assembly 68. Conduits that have a unitary construction may be used
for transporting the liquid fuel into the fuel nozzle tip assembly
68 of the fuel nozzles. The fuel supply conduits, may be located
within the stem 83 and coupled to a fuel distributor tip 180. Pilot
fuel and main fuel are sprayed into the combustor by fuel nozzle
tip assemblies 68, such as for example, shown in FIGS. 1 and 2.
During operation of the turbine engine, initially, pilot fuel is
supplied through a pilot fuel flow passage, such as, for example,
shown as items 102, 104 in FIG. 2, during pre-determined engine
operation conditions, such as during startup and idle operations.
The pilot fuel is discharged from fuel distributor tip 180 through
the pilot fuel outlets 162, 164. When additional power is demanded,
main fuel is supplied through main fuel passageways 105 (see FIG.
2) and the main fuel is sprayed using the main fuel outlets
165.
[0032] FIG. 1 is a partial cross-sectional isometric view of an
exemplary fuel nozzle 100 having a unitary conduit 80 used for
transporting liquid fuel in a fuel nozzle tip 68. In the exemplary
embodiment, the unitary conduit 80 includes one or more flow
passages located within the conduit. Fuel from the flow passages is
directed into the fuel nozzle tip 68 by a pilot supply tube 154
(see FIG. 1) and exits through a pilot fuel outlet 162. In some
unitary conduits 80, it is advantageous to have a flow passage that
branches into two or more sub-passages within the conduit.
[0033] An exemplary repairable fuel nozzle 100 having a unitary
conduit 80 as described herein and used in a gas turbine engine
fuel nozzle is shown in FIGS. 1 and 2. In the exemplary embodiment,
a unitary conduit 80 is located within a stem 83 which has a flange
81 for mounting in a gas turbine engine 10. The unitary conduit 80
is located within the stem 83 such that there is a gap 77 between
the interior of the stem and the conduit body 80 of the unitary
conduit 80. The gap 77 insulates the unitary conduit 80 from heat
and other adverse environmental conditions surrounding the fuel
nozzle in gas turbine engines. Additional cooling of the unitary
conduit 80 may be accomplished by circulating air in the gap 77.
The unitary conduit 80 is attached to the stem 83 using
conventional attachment means such as brazing. Alternatively, the
unitary conduit 80 and the stem 83 may be made by rapid
manufacturing methods such as for example, direct laser metal
sintering, described herein. In the exemplary embodiment of a
repairable fuel nozzle 100 shown and described herein, fuel
distributor tip 68 extends from the unitary conduit 80 and stem 83
such that main fuel passageways and the pilot fuel passageways are
coupled in flow communication with a fuel distributor 300, such as,
for example, shown in the figures herein. It will be apparent to
those skilled in the art that, although the conduit 80 and the
distributor ring 171 have been described herein above as a unitary
conduit (i.e., having a unitary construction), it is possible to
use conduits 80 having other suitable manufacturing constructs
using methods known in the art. The unitary distributor ring 171 is
attached to the stem 83 using conventional attachment means such as
brazing. Alternatively, the unitary distributor ring 171 and the
stem 83 may be made by rapid manufacturing methods such as for
example, direct laser metal sintering, described herein.
[0034] FIGS. 2 and 14 shows an axial cross-sectional view of the
exemplary nozzle tip assembly 68 of the exemplary repairable fuel
nozzle 100 shown in FIGS. 1, 2 and 14. The exemplary nozzle tip
assembly 68 comprises a distributor 300 which receives the fuel
flow from the supply conduit 80, such as described previously, and
distributes the fuel to various locations in the fuel nozzle tip
68, such as main fuel passages and pilot fuel passages. FIGS. 2 and
14 show exemplary embodiments of the present invention having two
pilot flow passages 102, 104 that distribute the fuel in a fuel
nozzle tip assembly 68.
[0035] The exemplary distributor 300 shown in FIGS. 2 and 14
comprises a distributor ring body 171 that contains the main flow
passages and pilot flow passages described herein. The main flow
passages 105 in the distributor 300 are in flow communication with
corresponding main flow passages in the supply conduit 80. The
exemplary main fuel passages shown and described herein each
comprise an inlet portion that transport the fuel flow from the
supply conduit 80 to two arcuate portions 105 that are located
circumferentially around a nozzle tip axis 11.
[0036] The term "unitary" is used in this application to denote
that the associated component, such as, for example, the venturi
500 described herein, is made as a single piece during
manufacturing. Thus, a unitary component has a monolithic
construction for the component.
[0037] FIGS. 2 and 14 show axial cross-sections of an exemplary
nozzle tip 68 of an exemplary embodiment of the present invention
of a repairable fuel nozzle 100. The exemplary fuel nozzle tip 68
shown in FIGS. 2 and 14 has two pilot fuel flow passages, referred
to herein as a primary pilot flow passage 102 and a secondary pilot
flow passage 104. Referring to FIG. 4, the fuel from the primary
pilot flow passage 102 exits the fuel nozzle through a primary
pilot fuel injector 163 and the fuel from the secondary pilot flow
passage 104 exits the fuel nozzle through a secondary pilot fuel
injector 167 (see FIG. 14). The primary pilot flow passage 102 in
the distributor ring 171 is in flow communication with a
corresponding pilot primary passage in the supply conduit 80
contained within the stem 83. Similarly, the secondary pilot flow
passage 104 in the distributor ring 171 is in flow communication
with a corresponding pilot secondary passage 80 in the supply
conduit contained within the stem 83.
[0038] As described previously, fuel nozzles, such as those used in
gas turbine engines, are subject to high temperatures. Such
exposure to high temperatures may, in some cases, result in fuel
coking and blockage in the fuel passages, such as for example, the
exit passage 164. One way to mitigate the fuel coking and/or
blockage in the distributor ring 171 is by using heat shields to
protect the passages (such as items 102, 104, 105 shown in FIG. 14)
from the adverse thermal environment. In the exemplary embodiment
shown in FIG. 14, the fuel conduits 102, 104, 105 are protected by
gaps 116 and heat shields that at least partially surround these
conduits. The gap 116 provides protection to the fuel passages by
providing insulation from adverse thermal environment. In the
exemplary embodiment shown, the insulation gaps 116 have widths
between about 0.015 inches and 0.025 inches. The heat shields, such
as those described herein, can be made from any suitable material
with ability to withstand high temperature, such as, for example,
cobalt based alloys and nickel based alloys commonly used in gas
turbine engines. In exemplary embodiment shown in FIG. 14, the
distributor ring 171 has a unitary construction wherein the
distributor ring 171, the flow passages 102, 104, 105, the fuel
outlets 165, the heat shields and the gaps 116 are formed such that
they have a monolithic construction made using a DMLS process such
as described herein.
[0039] FIGS. 2 and 14 show a swirler 200 assembled inside an
exemplary repairable fuel nozzle 100 according to an exemplary
embodiment of the present invention. The exemplary swirler 200
comprises a body 201 having a hub 205 that extends
circumferentially around a swirler axis 11. A row of vanes 208
extending from the hub 205 are arranged in a circumferential
direction on the hub 205, around the nozzle tip axis 11. Each vane
208 has a root portion located radially near the hub 205 and a tip
portion that is located radially outward from the hub 205. Each
vane 208 has a leading edge and a trailing edge that extend between
the root portion and the tip portion. The vanes 208 have a suitable
shape, such as, for example, an airfoil shape, between the leading
edge and the trailing edge. Adjacent vanes form a flow passage for
passing air, such as the CDP air shown as item 190 in FIG. 2, that
enters the swirler 200. The vanes 208 can be inclined both radially
and axially relative to the axis 11 to impart a rotational
component of motion to the incoming air 190 that enters the swirler
200. These inclined swirler vanes 208 cause the air 190 to swirl in
a generally helical manner within the fuel nozzle tip assembly 68.
In one aspect of the swirler 200, the vane 208 has a fillet that
extends between the root portion and the hub to facilitate a smooth
flow of air in the swirler hub region. In the exemplary embodiments
shown herein, the vanes 208 have a cantilever-type of support,
wherein it is structurally supported at its root portion on the hub
205 with the vane tip portion essentially free. It is also
possible, in some alternative swirler designs, to provide
additional structural support to at least some of the vanes 208 at
their tip regions. In another aspect of the swirler 200, a recess
is provided on the tip portion of a vane. During assembly of the
repairable fuel nozzle 100, the recess engages with adjacent
components in a repairable fuel nozzle 100 to orient them axially,
such as for example, shown in FIGS. 2 and 14.
[0040] The exemplary swirler 200 shown in FIGS. 2 and 14 comprises
an adaptor 250 that is located axially aft from the circumferential
row of vanes 208. The adaptor 250 comprises an arcuate wall 256
(see FIG. 2) that forms a flow passage 254 for channeling an air
flow 190, such as for example, the CDP air flow coming out from a
compressor discharge in a turbo fan engine. The in-coming air 190
enters the passage 254 in the adaptor 250 and flows axially forward
towards the row of vanes 208 of the swirler 200. The adaptor 250
also serves as a means for mounting the swirler 200 in a nozzle tip
assembly 68, as shown in FIG. 14. In the exemplary embodiment shown
in FIG. 14, the adaptor 250 comprises an arcuate groove 252 for
receiving a brazing material that is used for attaching the adaptor
250 to another structure, such as, for example, a fuel nozzle stem
83. The braze-groove 252 in the arcuate wall 256 has a complex
three-dimensional geometry that is difficult to form using
conventional machining methods. In one aspect of the present
invention, the groove in the arcuate wall 256 having a complex
three-dimensional geometry is formed integrally to have a unitary
construction, using the methods of manufacturing described
subsequently herein. In a preferred embodiment, the adaptor 250,
the body 201, the hub 205 and the vanes 208 have a unitary
construction using the methods of manufacture described herein.
Alternatively, the adaptor 250 may be manufactured separately and
attached to body 201 using conventional attachment means.
[0041] It is common in combustor and fuel nozzle applications that
the compressor discharge air 190 (see FIG. 2) coming into the
combustor and fuel nozzle regions is very hot, having temperatures
above 800 Deg. F. Such high temperature may cause coking or other
thermally induced distress for some of the internal components of
fuel nozzles 100 such as, for example, the fuel flow passages 102,
104, swirler 200 and venturi 500. The high temperatures of the air
190 may also weaken the internal braze joints, such as, for
example, between the fuel injector 163 and the distributor ring
body 171 (see FIG. 14). In one aspect of the present invention,
insulation gaps 216 are provided within the body 201 of the swirler
200 to reduce the transfer of heat from the air flowing in the
repairable fuel nozzle 100 and its internal components, such as
primary fuel injectors 163 or secondary fuel injectors 167. The
insulation gaps, such as items 116 and 216 in FIG. 14, help to
reduce the temperature at the braze joints in a fuel nozzle
assembly during engine operations. The insulation gap 216 may be
annular, as shown in FIG. 14. Other suitable configurations based
on known heat transfer analysis may also be used. In the exemplary
embodiment shown in FIG. 14, the insulation gap is annular
extending at least partially within the swirler body 201, and has a
gap radial width of between about 0.015 inches and 0.025 inches. In
one aspect of the present invention, the insulation gap 216 may be
formed integrally with the swirler body 201 to have a unitary
construction, using the methods of manufacturing described
subsequently herein. The integrally formed braze groves, such as
those described herein, may have complex contours and enable
pre-formed braze rings to be installed to promote easy
assembly.
[0042] Referring to FIG. 2, it is apparent to those skilled in the
art that the airflow 190 entering from the adaptor passage 254 is
not uniform in the circumferential direction when it enters the
vanes 208. This non-uniformity is further enhanced by the presence
of the wall 260. In conventional swirlers, such non-uniformity of
the flow may cause non-uniformities in the mixing of fuel and air
and lead to non-uniform combustion temperatures. In one aspect of
the present invention of a repairable fuel nozzle 100, the adverse
effects of circumferentially non-uniform flow entry can be
minimized by having swirler vanes 208 with geometries that are
different from those of circumferentially adjacent vanes.
Customized swirler vane 208 geometries can be selected for each
circumferential location on the hub 205 based on known fluid flow
analytical techniques. A swirler having different geometries for
the vanes 208 located at different circumferential locations can
have a unitary construction and made using the methods of
manufacture described herein.
[0043] FIGS. 2 and 14 show an exemplary venturi 500 according to an
exemplary embodiment of the present invention. The exemplary
venturi 500 comprises an annular venturi wall 502 around the nozzle
tip axis 11 that forms a mixing cavity 550 wherein a portion of air
and fuel are mixed. The annular venturi wall may have any suitable
shape in the axial and circumferential directions. A conical shape,
such as shown for example in FIG. 14, that allows for an expansion
of the air/fuel mixture in the axially forward direction is
preferred. The venturi wall 502 has at least one groove 504 (see
FIG. 18) located on its radially exterior side capable of receiving
a brazing material during assembly of a nozzle tip assembly 68. In
the exemplary embodiment shown in FIG. 18, two annular grooves 504,
564 are shown, one groove 564 near the axially forward end and
another groove 504 near an intermediate location between the
axially forward end and the axially aft end. The grooves 504 may be
formed using conventional machining methods. Alternatively, the
grooves 504 may be formed integrally when the venturi wall 502 is
formed, such as, for example, using the methods of manufacturing a
unitary component 700 (see FIG. 3) as described herein. In another
aspect of the present invention, the venturi 500 comprises a lip
518 (alternatively referred to herein as a drip-lip 518) located at
the axially aft end of the venturi wall 502. The drip-lip 518 has a
geometry (see FIG. 18) such that liquid fuel particles that flow
along the inner surface 503 of the venturi wall 502 separate from
the wall 502 and continue to flow axially aft. The drip-lip 518
thus serves to prevent the fuel from flowing radially outwards
along the venturi walls at exit.
[0044] As shown in FIGS. 2 and 14, the exemplary embodiment of
venturi 500 comprises an annular splitter 530 having an annular
splitter wall 532 located radially inward from the annular venturi
wall 502 and coaxially located with it around the axis 11. The
radially outer surface 533 of the splitter 530 and the radially
inner surface 503 of the venturi wall 502 form an annular
swirled-air passage 534. The forward portion of the splitter wall
532 has a recess (see FIG. 14) that facilitates interfacing the
venturi 500 with an adjacent component, such as for example, shown
as item 208 in FIG. 14, during assembly of a fuel nozzle tip
assembly 68.
[0045] The exemplary embodiment of the venturi 500 shown in FIGS. 2
and 14 comprises a swirler 510. Although the swirler 510 is shown
in FIG. 14 as being located at the axially forward portion of the
venturi 500, in other alternative embodiments of the present
invention, it may be located at other axial locations within the
venturi 500. The swirler 510 comprises a plurality of vanes 508
that extend radially inward between the venturi wall 502 and the
annular splitter 530. The plurality of vanes 508 are arranged in
the circumferential direction around the axis 11.
[0046] Referring to FIGS. 2 and 14, in the exemplary embodiment of
the swirler 510 shown therein, each vane 508 has a root portion
located radially near the splitter and a tip portion that is
located radially near the venturi wall 502. Each vane 508 has a
leading edge and a trailing edge that extend between the root
portion and the tip portion. The vanes 508 have a suitable shape,
such as, for example, an airfoil shape, between the leading edge
and the trailing edge. Circumferentially adjacent vanes 508 form a
flow passage for passing air, such as the CDP air shown as item 190
in FIG. 2, that enters the swirler 510. The vanes 508 can be
inclined both radially and axially relative to the axis 11 to
impart a rotational component of motion to the incoming air 190
that enters the swirler 510. These inclined vanes 508 cause the air
190 to swirl in a generally helical manner within venturi 500. In
one aspect of the present invention, the vane 508 has a fillet that
extends between the root portion of the vane and the splitter wall.
The fillet facilitates a smooth flow of air within the swirler and
in the swirled air passage. The fillet has a smooth contour shape
that is designed to promote the smooth flow of air in the swirler.
The contour shapes and orientations for a particular vane 508 are
designed using known methods of fluid flow analysis. Fillets having
suitable fillet contours may also be used between the tip portion
of the vane and the venturi wall 502. In the exemplary embodiment
of the venturi 500 shown in FIGS. 2 and 14 herein, the vanes 508
are supported near both the root portion and the tip portion. It is
also possible, in some alternative venturi designs, to have a
swirler comprising vanes having a cantilever-type of support,
wherein a vane is structurally supported at only one end, with the
other end essentially free. The venturi 500 may be manufactured
from known materials that can operate in high temperature
environments, such as, for example, nickel or cobalt based super
alloys, such as CoCr, HS188, N2 and N5.
[0047] The venturi 500 comprises a heat shield 540 for protecting
venturi and other components in the fuel nozzle tip assembly 68
(see FIGS. 2 and 14) from the flames and heat from ignition of the
fuel/air mixture in a repairable fuel nozzle 100. The exemplary
heat shield 540 shown in FIGS. 2 and 14 has an annular shape around
the axis 11 and is located axially aft from the swirler 510, near
the axially aft end 519 of the venturi 500. The heat shield 540 has
an annular wall 542 that extends in a radially outward direction
from the swirler axis 11. The annular wall 542 protects venturi 500
and other components in the repairable fuel nozzle 100 from the
flames and heat from ignition of the fuel/air mixture, having
temperatures in the range of 2500 Deg. F. to 4000 Deg. F. The heat
shield 540 is made from a suitable material that can withstand high
temperatures. Materials such as, for example, CoCr, HS188, N2 and
N5 may be used. In the exemplary embodiments shown herein, the heat
shield 540 is made from CoCr material, and has a thickness between
0.030 inches and 0.060 inches. It is possible, in other embodiments
of the present invention, that the heat shield 540 may be
manufactured from a material that is different from the other
portions the venturi, such as the venturi wall 502 or the swirler
510.
[0048] The exemplary venturi 500 shown in FIGS. 2, 14 and 18 has
certain design features that enhance the cooling of the heat shield
540 to reduce its operating temperatures. The exemplary venturi 500
comprises at least one slot 544 extending between the venturi wall
502 and the heat shield 540. The preferred exemplary embodiment of
the venturi 500, shown in FIGS. 2 and 14, comprises a plurality of
slots 544 extending between the venturi wall 502 and the heat
shield 540 wherein the slots 544 are arranged circumferentially
around the swirler axis 11. The slots 544 provide an exit passage
for cooling air that flows through the cavity between the fuel
conduit and the venturi wall 502 (See FIG. 14). The cooling air
entering the axially oriented portion of each slot 544 is
redirected in the radially oriented portion of the slot 544 to exit
from the slots 544 in a generally radial direction onto the side of
the annular wall 542 of the heat shield. In another aspect of the
present invention, the exemplary venturi 500 comprises a plurality
of bumps 546 located on the heat shield 540 and arranged
circumferentially on the axially forward side of the heat shield
wall 542 around the axis 11. These bumps 546 provide additional
heat transfer area and increase the heat transfer from the heat
shield 540 to the cooling air directed towards, thereby reducing
the operating temperatures of the heat shield 540. In the exemplary
embodiment shown in FIG. 14, the bumps 546 are arranged in four
circumferential rows, with each row having between 100 and 120
bumps.
[0049] Referring to FIGS. 2 and 14, it is apparent to those skilled
in the art that a portion of the airflow 190 entering the swirler
510 of the venturi 500, in some cases, may not be uniform in the
circumferential direction when it enters passages between the vanes
508. This non-uniformity is further enhanced by the presence of
other features, such as, for example, the wall 260 (see FIG. 14).
In conventional venturis, such non-uniformity of the flow may cause
non-uniformities in the mixing of fuel and air in the venturi and
lead to non-uniform combustion temperatures. In one aspect of the
present invention, the adverse effects of circumferentially
non-uniform flow entry can be minimized by having a swirler 510
comprising some swirler vanes 508 with geometries that are
different from those of circumferentially adjacent vanes.
Customized swirler vane 508 geometries can be selected for each
circumferential location based on known fluid flow analytical
techniques. A venturi 500 having swirlers with different geometries
for the vanes 508 located at different circumferential locations
can have a unitary construction and made using the methods of
manufacture described herein.
[0050] The exemplary embodiment of a repairable fuel nozzle 100
shown herein comprises an annular centerbody 450. The centerbody
450 comprises an annular outer wall 461 that, in the assembled
condition of the repairable fuel nozzle 100 as shown in FIG. 14,
surround the forward portion of the distributor 300 and forms an
annular passage 462 for air flow. A feed air stream for cooling the
fuel nozzle 100 enters the air flow passage 412 between the
centerbody outer wall 461 and the distributor 300 and flows past
the fuel posts 165, facilitating the cooling of the distributor
300, centerbody 450 and fuel orifices and fuel posts 165. The outer
wall 461 has a plurality of openings 463 that are arranged in the
circumferential direction, corresponding to the orifices in the
circumferential row of fuel posts 165. Fuel ejected from the fuel
posts 165 exits from the fuel nozzle 100 through the openings 463.
In the exemplary fuel nozzle 100, scarfs are provided near openings
463 at the main fuel injection sites on the outer side of the
centerbody 450 wall 461 for fuel purge augmentation. In some
embodiments, such as shown in FIG. 14, it is possible to have a
small gap 464 between the inner diameter of the outer wall 461 and
the outer end of the fuel posts 165. In the exemplary embodiment
shown in FIG. 14, this gap ranges between about 0.000 inches to
about 0.010 inches.
[0051] In the exemplary embodiment shown in FIGS. 2 and 14, the
centerbody wall 461 is cooled by a multi-hole cooling system which
passes a portion of the feed air stream entering the repairable
fuel nozzle 100 through one or more circumferential rows of
openings 456. The multi-hole cooling system of the centerbody may
typically use one to four rows of openings 456. The openings 456
may have a substantially constant diameter. Alternatively, the
openings 456 may be diffuser openings that have a variable cross
sectional area. In the exemplary embodiments shown in FIG. 14, the
centerbody 450 has three circumferential rows of openings 456, each
row having between 60 to 80 openings and each opening having a
diameter varying between about 0.020 inches and 0.030 inches. As
shown in FIG. 14 the openings 456 can have a complex orientation in
the axial, radial and tangential directions within the centerbody
outer wall 461. Additional rows of cooling holes 457 arranged in
the circumferential direction in the centerbody wall 461 are
provided to direct the cooling air stream toward other parts of the
repairable fuel nozzle 100, such as the heat shield 540. In the
exemplary embodiment shown in FIGS. 2 and 14, the repairable fuel
nozzle 100 comprises an annular heat shield 540 located at one end
of the venturi 540. The heat shield 540 shields the repairable fuel
nozzle 100 components from the flame that is formed during
combustion in the combustor. The heat shield 540 is cooled by one
or more circumferential rows of holes 457 having an axial
orientation as shown in FIG. 14 that direct cooling air to impinge
on the heat shield 540. In the exemplary fuel nozzle 100 described
herein, the holes 457 typically have a diameter of at least 0.020
inches arranged in a circumferential row having between 50 to 70
holes, with a hole size preferred between about 0.026 inches to
about 0.030 inches. The centerbody 450 may be manufactured from
known materials that can operate in high temperature environments,
such as, for example, nickel or cobalt based super alloys, such as
CoCr, HS188, N2 and N5. The cooling holes 456, 457 openings 463 and
scarfs 452, 454 in the centerbody 450 may be made using known
manufacturing methods. Alternatively, these features of the
centerbody can be made integrally using the manufacturing methods
for unitary components described herein, such as, preferably, the
DMLS method shown in FIG. 3 and described herein. In another
embodiment of the invention, a heat shield similar to item 540
shown in FIG. 14 may be made integrally to have a unitary
construction with centerbody 450 using the DMLS method. In another
embodiment of the invention, the centerbody 450, the venturi 500
and a heat shield similar to item 540 shown in FIG. 14 may be made
integrally to have a unitary construction using the DMLS
method.
[0052] The exemplary embodiment of the repairable fuel nozzle 100
described herein may comprise some unitary components such as, for
example, the unitary conduit 80/distributor 300, unitary swirler
200, unitary venturi 500 and unitary centerbody 450. Such unitary
components used in the fuel nozzle 100 can be made using rapid
manufacturing processes such as Direct Metal Laser Sintering
(DMLS), Laser Net Shape Manufacturing (LNSM), electron beam
sintering and other known processes in the manufacturing. DMLS is
the preferred method of manufacturing the unitary components used
in the repairable fuel nozzle 100, such as, for example, the
unitary conduit 80/distributor 300, unitary swirler 200, unitary
venturi 500 and unitary centerbody 450 described herein.
[0053] FIG. 3 is a flow chart illustrating an exemplary embodiment
of a method 700 for fabricating unitary components for repairable
fuel nozzle 100, such as, for example, shown as items 80, 200, 300,
450 and 500 in FIGS. 2 and 14 and described herein. Although the
method of fabrication 700 is described below using unitary
components 80, 200, 300, 450 and 500 as examples, the same methods,
steps, procedures, etc. apply for alternative exemplary embodiments
of these components. Method 700 includes fabricating a unitary
component used in a repairable fuel nozzle 100 such as, for
example, a venturi 500, using Direct Metal Laser Sintering (DMLS).
DMLS is a known manufacturing process that fabricates metal
components using three-dimensional information, for example a
three-dimensional computer model, of the component. The
three-dimensional information is converted into a plurality of
slices, each slice defining a cross section of the component for a
predetermined height of the slice. The component is then "built-up"
slice by slice, or layer by layer, until finished. Each layer of
the component is formed by fusing a metallic powder using a
laser.
[0054] Accordingly, method 700 includes the step 705 of determining
three-dimensional information of a specific unitary component 80,
200, 300, 450, 500 in the repairable fuel nozzle 100 and the step
710 of converting the three-dimensional information into a
plurality of slices that each define a cross-sectional layer of the
unitary component. The unitary component 80, 200, 300, 450, 500 is
then fabricated using DMLS, or more specifically each layer is
successively formed in step 715 by fusing a metallic powder using
laser energy. Each layer has a size between about 0.0005 inches and
about 0.001 inches. Unitary components 80, 200, 300, 450, 500 may
be fabricated using any suitable laser sintering machine. Examples
of suitable laser sintering machines include, but are not limited
to, an EOSINT.TM. M 270 DMLS machine, a PHENIX PM250 machine,
and/or an EOSINT.TM.M 250 Xtended DMLS machine, available from EOS
of North America, Inc. of Novi, Mich. The metallic powder used to
fabricate unitary components 80, 200, 300, 450, 500 is preferably a
powder including cobalt chromium, but may be any other suitable
metallic powder, such as, but not limited to, HS188 and INCO625.
The metallic powder can have a particle size of between about 10
microns and 74 microns, preferably between about 15 microns and
about 30 microns.
[0055] Although the methods of manufacturing unitary components 80,
200, 300, 450, 500 in the fuel nozzle 100 have been described
herein using DMLS as the preferred method, those skilled in the art
of manufacturing will recognize that any other suitable rapid
manufacturing methods using layer-by-layer construction or additive
fabrication can also be used. These alternative rapid manufacturing
methods include, but not limited to, Selective Laser Sintering
(SLS), 3D printing, such as by inkjets and laserjets,
Sterolithography (SLS), Direct Selective Laser Sintering (DSLS),
Electron Beam Sintering (EBS), Electron Beam Melting (EBM), Laser
Engineered Net Shaping (LENS), Laser Net Shape Manufacturing (LNSM)
and Direct Metal Deposition (DMD).
[0056] Another aspect of the present invention comprises a simple
method of assembly or re-assembly of the repairable fuel nozzle 100
having components with complex geometrical features as described
earlier herein. The use of unitary components in the fuel nozzle
100 as described herein has enabled the assembly of repairable fuel
nozzle 100 having fewer number of components and with fewer number
of joints than conventional nozzles. For example, in the exemplary
embodiment of the repairable fuel nozzle 100 shown herein, the fuel
nozzle tip 68 comprises only nine braze joints and two weld joints
after repair, whereas some known conventional nozzles have twenty
two braze joints and three weld joints.
[0057] An exemplary method of repairing 850 a fuel nozzle according
to the present invention is shown in FIG. 4 and associated Steps
are described in detail below. The exemplary method of repairing
850 shown FIG. 4 can be used to repair the exemplary repairable
fuel nozzle 100 described previously herein.
[0058] Referring to FIG. 4, in Step 852, the first step is to open
an access to interior of the fuel nozzle tip assembly 68. In the
exemplary repairable nozzle 100, the nozzle tip assembly 68 is
coupled to a stem 83 (See FIGS. 1 and 2). An access to the nozzle
tip assembly may be created by machining through the stem 83. In
the exemplary embodiment of a repairable nozzle 100 shown herein,
the stem 83 has a cover plate 802 coupled to it, such as, for
example by welding or brazing. The weld plate 802 is located around
the fuel nozzle tip axis 11 (See FIGS. 1 and 2) such that by
removing the weld plate, it is possible to access some portions of
the distributor 300 near the nozzle tip axis 11. A preferred method
of removing the cover plate is by drilling using a drill tool 812
along the drilling direction 813, along the nozzle tip axis 11, as
shown in FIG. 5.
[0059] In Step 854, the primary orifice and its associated
components such as, for example, a primary fuel swirler 603, are
removed from the fuel nozzle 100. The secondary orifice 809, if
present, and its associated components, may also be removed in this
step. The preferred method of removing these components is by
drilling using a drill 812 along the fuel nozzle tip axis 11, as
shown in FIG. 5.
[0060] In Step 856, a preformed braze wire 602 is inserted into a
braze groove 601 in Primary Fuel Swirler 603 as shown in FIG. 6.
The braze wire material can be a known braze material, such as
AMS4786 (gold nickel alloy). In FIG. 6 the exemplary braze wire 602
has a circular cross section. Other suitable cross sectional shapes
for the braze wire 602 and corresponding shapes for the braze grove
601 can be used.
[0061] In Step 858 the Primary Fuel Swirler 603 is installed, such
as for example, by press-fit, into the Primary Orifice 606 as shown
in FIG. 7.
[0062] In Step 860, the Primary Fuel Swirler 603 and Primary
Orifice 606 are brazed together to form a new Primary Pilot
Assembly 807 as shown in FIG. 7. Brazing is performed using known
methods. A brazing temperature of between 1840 Deg. F. and 1960
Deg. F. can be used. Brazing at a temperature of 1950 Deg. F. is
preferred.
[0063] In Step 862, the new primary pilot assembly 807 is inserted
into a secondary orifice 809. The secondary orifice 809 comprises a
cylindrical wall 840 that is substantially coaxial with the primary
orifice 606. In the exemplary embodiment shown in FIGS. 8-10, the
primary orifice 606 and the secondary orifice 809, when assembled
as described herein, form an inner pilot flow passage 169 and an
annular outer pilot flow passage 168. The secondary orifice 809 has
a step 803 located on the interior side of the cylindrical wall 840
that facilitates locating the new primary pilot assembly 807 in the
new primary pilot assembly 807, as shown in FIG. 10. Other suitable
geometrical features may alternatively be used for this purpose. In
addition, the secondary orifice 809 has a step 804 located on the
exterior side of the cylindrical wall 840 that facilitates locating
the new pilot assembly 808 in the nozzle tip assembly 68, as shown
in FIGS. 10-14. Other suitable geometrical features may
alternatively be used for this purpose.
[0064] In the optional Step 864, fuel flow check on the new pilot
assembly 808 is performed, to check the fuel flow patterns in the
pilot fuel flow circuits, the inner pilot flow passage 169 and the
annular outer pilot flow passage 168. An exemplary arrangement is
shown in FIG. 8, showing a primary pilot flow circuit 608 and a
secondary pilot flow circuit 609 in flow communication with the
inner pilot flow passage 169 and the annular outer pilot flow
passage 168. Suitable test fixtures known in the art, such as for
example shown as item 604 in FIG. 8 may be used during the optional
flow checking step 864. Known sealing methods, such as for example
using O-rings 616 shown in FIG. 8, may be used for preventing fuel
leakage during the optional flow checking step 864. After flow
checking is completed, the pilot assembly 808 is removed from test
fixture 604.
[0065] In the optional Step 866, a non-destructive inspection of
the braze joint in the primary pilot assembly 807 is performed, as
shown for example in FIG. 9. X-ray inspection using known
techniques is preferred for inspecting the braze joint. X-rays 610
from a known X-ray source 611 can be used.
[0066] In Step 868, a preformed braze-wire 805 is inserted into a
braze-groove 806 in secondary orifice 809 as shown in FIG. 10. The
braze wire material can be a known braze material, such as AMS4786
(gold nickel alloy). In FIG. 10 the exemplary braze wire 805 has a
circular cross section. Other suitable cross sectional shapes for
the braze wire 805 and corresponding shapes for the braze grove 806
can be used.
[0067] In Step 870, the new sub-assembly from Step 868 comprising
the pilot assembly 808 with braze-wire 805 is installed in the
repair bore 801 of the nozzle, as shown in FIG. 1. The pilot
assembly is installed such that the braze-wire 805 is in contact
with the distributor ring body 301. A suitable placement fixture
811, such as for example shown in FIG. 11, is used to locate the
pilot assembly 808 to be substantially co-axial with the nozzle tip
axis 11. A locating feature, such as the step 804 on the wall 840
of the secondary orifice 809 is used to locate the pilot assembly
808 with respect to other components in the nozzle tip 68 (see FIG.
11).
[0068] In Step 872, a primary adaptor 820 is supplied. The primary
adaptor 820 is a component that receives a fuel flow from a fuel
flow passage in the distributor 300 and directs that fuel flow to
pilot fuel injectors and orifices. An exemplary embodiment of a
primary adaptor 820 is shown in FIG. 12. It comprises a body having
a flow passage 822 having an inlet 821 and an exit 823. In the
exemplary embodiment shown in FIG. 12, the exit 823 is located at a
front end 824 of the primary adaptor 820. In some applications, the
primary adaptor 825 may have features, such as for example, shown
as items 826 and 827 in FIG. 12, that enable the primary adaptor
820 to form flow passages when the primary adaptor 820 is installed
in a fuel nozzle 100. The exemplary primary adaptor 820 has
braze-grooves that can receive braze-wires during assembly. In the
exemplary primary adaptor 820 shown in FIG. 12, braze-groove 836 is
located near the front end 824, braze-grooves 832 and 834 are
located in the body. An embossment 827 is located near the front
end 824 for axially locating the primary adaptor 820 during
assembly. The primary adaptor may be manufactured using known
materials and methods such as milling and drilling. The exemplary
primary adaptor 820 shown in FIG. 12 is made from commercially
available Hast X material and conventionally machined. In other
applications, the flow path inside the body 825 and the features
outside the primary adaptor may have complex geometric features. In
these applications, alternative embodiments of the primary adaptor
820 may be used wherein the primary adaptor is made using rapid
manufacturing techniques described herein, such as for example,
DMLS (see FIG. 3). Referring to FIG. 14, when the repair and
reassembly of the nozzle tip 68 is completed as described herein,
the flow passage 822 supplies fuel received from the primary pilot
flow passage 102 in the distributor 300 at the inlet 821 and
directs that fuel flow to the inner pilot flow passage 169. As
shown in FIG. 14, a portion 826 of the body 825 forms a portion of
the secondary pilot passage 828. This portion 828 receives fuel
flow from the secondary pilot flow passage 104 in the distributor
300 and directs that fuel flow into an outer pilot flow passage
168. Although the primary adaptor 820 is described herein (see FIG.
14) in the context of a fuel nozzle 100 having two pilot flow
injectors (a primary pilot injector 163 and a secondary pilot
injector 167), the present invention is not thus limited. Those
skilled in the art will recognize that the present invention
disclosed herein encompasses alternative fuel nozzles having only
one pilot injector and those fuel nozzles having more than two fuel
injectors.
[0069] In Step 874, preformed braze-wires are inserted into
braze-grooves in the primary adaptor 820. As shown in FIG. 12, a
preformed braze-wire 835 is inserted into a braze-groove 836, a
preformed braze-wire 831 is inserted into a braze-groove 832 and a
preformed braze-wire 833 is inserted into a braze-groove 834. The
braze wire material can be a known braze material, such as AMS4786
(gold nickel alloy). In FIG. 12 the exemplary braze-wires 831, 833,
835 have circular cross-sections. Other suitable cross-sectional
shapes for the braze-wires 831, 833, 835 and corresponding shapes
for the braze-groves 832, 834, 836 can alternatively be used.
[0070] In Step 876, the primary adaptor 820 is inserted into the
repair bore 801 as shown in FIG. 13. The front end 824 of the
primary adaptor 820 fits into the pilot assembly 808. The
braze-wire 835 in the braze-groove 836 of the primary adaptor 820
is in contact with secondary orifice 809 wall. The flow passage 822
near the exit 823 of the primary adaptor 820 is substantially
coaxial with the fuel nozzle axis 11. Braze-wires 831, 833, 835 in
braze-groves 832, 834, 836 of the primary adaptor 820 are in
contact with the distributor 300 walls as shown in FIG. 13.
[0071] In Step 878, the assembly from Step 876 shown in FIG. 13
having braze-wires 831, 833, 835 is brazed. Brazing is performed
using known methods. A brazing temperature of between 1800 Deg. F.
and 1860 Deg. F. can be used. Brazing at a temperature of 1850 Deg.
F. is preferred.
[0072] In the optional Step 880, a non-destructive inspection of
the braze joints formed in Step 878 (see FIG. 13) is performed.
X-ray inspection using known techniques is preferred for inspecting
the braze joint.
[0073] In Step 882, a cover plate 802 is welded to assembly
obtained from Step 880, as shown in FIG. 14, such that axial access
bore in the stem 83 is sealed. Known welding methods can be used
for this purpose. A preferred welding method is TIG welding, using
HS188 weld wire.
[0074] In another aspect, the present invention discloses a method
of repair for use in repairing complex components in a repairable
fuel nozzle assembly by providing a method of repair for use to
repair a damaged component without having to disassemble the
component from a repairable fuel nozzle 100.
[0075] In an exemplary embodiment of a method of repairing a
damaged component in a fuel nozzle, LSNM has been used in the
repair of damaged parts. A powder is applied and fused on a part
along a toolpath to create a bead of the deposited material.
Deposited material beads are formed adjacent to and overlapping one
another to form a layer of the deposited material, then, a
plurality of layers are built upon one another until the part is
repaired. Alternatively, a layer of material can be formed
utilizing a single bead of material, then, a plurality of layers
are built upon one another until the part is repaired.
[0076] In Laser Net Shape Manufacturing (LNSM) method, the
dimensions and geometry of the component to be repaired are
modeled, such as for example, in accordance with a computer-aided
design (CAD) system, and from these representations, tool paths are
generated using known methods to drive the LNSM system.
[0077] A CAD model of a part to be repaired, such as for example
the venturi 500 heat shield 540 described herein, is generated by
numerically characterizing the shape of the venturi/heat shield
from drawings. Once the shape of the part is numerically
characterized, the computer generates a series of uniform slices
along the desired direction of material buildup, and the computer
determines a medial axis or spine (hereinafter referred to as a
medial axis) for each slice. It will be necessary to apply more
than one pass of material in a slice to re-build a desired geometry
of the heat shield 540. Tool-paths are determined using known
methods (such as, for example, as described in Publications US
2008/0314878 A1 and US 2008/0182017) based on the bead with, to
complete the build-up slice-by-slice. Alternatively, a series of
non-uniform slices along the desired direction of the material
build-up could be made, with the computer determining a medial axis
or spine for each slice. Adjacent beads of deposited material may
overlap to a determined extent to form a uniform layer. Adjacent
beads may overlap between about 10% to about 90%.
[0078] The movement of the deposition head, or equivalently, the
part, is then programmed using known numerical control computer
programs to create a pattern of instructions, to deposit material
along the determined medial axis path within a uniform or adaptive
thickness slice. The actual laser deposition parameters that are
used to deposit material will have been determined through prior
experimentation using known methods. Process parameters such as
laser power and toolpath speed are varied along the length of the
toolpath depending on the thickness of the slice cross-section. The
bead width can be varied by increasing the laser power and reducing
the deposition speed. Typically, laser power is increased where the
layer cross section is thicker and the laser power is reduced when
approaching the thinner sections of the layer.
[0079] FIG. 15 shows an exemplary damaged venturi 909 that has been
removed from a nozzle assembly. The damaged venturi 909 has a
damage area 910 from being exposed to high temperatures during
operation in a combustion environment, such as the combustor of an
engine. The venturi 500 described previously in the repairable
nozzle assembly 100, when exposed to high temperature environments
for a period of time, may appear like the damaged venturi 909 shown
in FIG. 15. As described previously herein, the heat shield 540
shields the fuel nozzle 100 components from the high temperature
flames. The damage arising from hot corrosion and erosion in a
combustion environment reduces the thickness of the heat shield
wall 542. The exemplary methods of repair described herein repair a
damaged venturi, such as for example shown in FIG. 15, by building
up the heat shield wall 542 and restoring substantially the same
geometry as that of the venturi 500. Although the methods of repair
described herein can be used to repair individual components, such
as item 909 shown in FIG. 15, they are particularly useful to
repair damaged components, such as a heat shield 540, in a nozzle
assembly 100, without having to disassemble the component from the
repairable nozzle assembly 100.
[0080] FIG. 16 shows an exemplary embodiment of the present
invention of a method of repair 920. For the repair of a fuel
nozzle component, such as a heat shield 540 in a venturi 500,
material is deposited to repair the damaged area 910 or section. In
step 922, a portion of the damaged component 909 is removed. It may
be necessary to grind a smooth and continuous surface onto the heat
shield damaged face 910 corresponding to the closest remaining
undamaged area or section, and then subsequently to deposit
material upon the surface until the heat shield 540 is repaired, as
described subsequently herein. FIG. 17 shows a venturi 909 and the
portion 912 that has been cut-off along a cut line 916 using
conventional machining. It should be noted that although the
venturi 500 is shown as an individual component in FIGS. 17, 18 and
19 for clarity, the exemplary steps 920 shown in FIG. 16, may be
performed without disassembling the components from the repairable
fuel nozzle 100.
[0081] In some cases, damage to the venturi/heat shield is in the
form of uneven and irregular shaped damage. In order to prepare the
venturi/heat shield for repair, the damaged area may be prepared by
machining away material in the area approximate to the damage in
order to form a smooth and continuous surface. This is shown in
FIG. 17, showing a cut line 916. Machining away the damage is
preferably conducted automatically in a multi-axis numerically
controlled milling machine that is programmed to form a
predetermined smooth surface. In Step 924, the machined area is
machined further, such as for example, for removing burrs. In Step
926, the repair region may be prepared further, as needed, by
aqueous cleaners and/or solvents, and dried. In step 928, the
repair is performed on the component 909 by building up material
(see FIG. 18) on a substrate 960 using a controlled deposition of
material to form a repaired part. In FIG. 18, material is built up
in an axial direction. An alternative way of repairing, using
building up material in a radial direction is shown in FIG. 19.
[0082] In repairing the venturi/heat shield using the methods
described herein, the composition of the powder feed 953 may be
maintained constant throughout the entire part. Alternatively, the
composition of the powder feed 953 may be intentionally varied
within any bead or as between successive beads, to produce
controllable composition variations in the article. For example, in
a heat shield, a tough heat resistant composition may be used near
the exposed surface.
[0083] A wide variety of materials may be deposited using the
approach of the invention. For example, metals and metal alloys
including nickel and nickel alloys, cobalt and cobalt alloys, and
iron and iron alloys, superalloys including Ni-based, Co-based, and
Fe based superalloys, ceramics and cermets may be deposited. The
deposited material may be a single material or a mixture of
different materials. Also, the deposited material may be varied or
changed during the deposition such that the bead of material is
formed of different materials or more than one material. Known
computer numerically controlled (CNC) methods may be used in the
repair process to control speed, turn on/off the laser, designate
laser power and powder flow. Some parameters that control the
process may be changed dynamically during the processing of a part,
including but not limited to laser power, tool velocity, powder
feed rate, and overlap ratio.
[0084] A Laser Net Shape Manufacturing (LNSM) desposition is
illustrated schematically in FIGS. 18 and 19. As shown in FIGS. 18
and 19, a powder supply (not shown) feeds a powder nozzle 952 for
deposition upon a substrate 960 on the heat shield 540. A laser 950
melts the powder as it is fed upon the substrate surface 960 and
melts the substrate surface to create a melt pool in the vicinity
where the laser 4950 is directed on the powder and the surface of
the substrate 960. The deposition system 965 and substrate 960 are
moved relatively to form a layer of a solidified deposited material
as the melt pool cools.
[0085] The path the laser 950 takes along the substrate 960 is
referred to as a toolpath. The deposited material is referred to as
a bead of material. The width of deposited material along the
toolpath is referred to as a bead width. The formed melt pool cools
and solidifies as the laser 950 moves along the substrate 960. More
than one powder feed may be used to form the deposited material,
and in this illustration, a second powder nozzle 952 is shown
contributing to the solidified deposited material. The laser 950,
by melting both the powder feed and the surface of the substrate
960, forms a strongly bonded deposited material.
[0086] Upon completion of a first bead of the deposited material,
the nozzle 952 and laser 950 are positioned and moved relative to
the substrate 960 so that an adjacent second bead of deposited
material may be deposited along side of the first bead, the width
of the second bead overlapping the width of the first bead. The
process is repeated until a layer of the deposited material is
formed.
[0087] The repairable fuel nozzle 100 for a turbine engine (see
FIGS. 1, 12, 14) and the method of repair 850 (see FIG. 4) comprise
fewer components and joints than known fuel nozzles and repair
methods. Specifically, the above described repairable fuel nozzle
100 requires fewer components because of the use of components and
assemblies such as, for example, primary adaptor 820 and pilot
assembly 808 and the disclosed methods of coupling these in the
repairable fuel nozzle 100. The repairable unitary venturi 500
having a repairable heat shield that is repairable without removing
it from the repairable fuel nozzle 100, as disclosed herein,
provides significant savings in cost. As a result, the described
repairable fuel nozzle 100 provides a lighter, less costly
alternative to known fuel nozzles. Moreover, the described unitary
construction for at least some of the fuel nozzle 100 components
and methods of assembly and repair 805 provide fewer opportunities
for leakage or failure and is more easily repairable compared to
known fuel nozzles.
[0088] As used herein, an element or step recited in the singular
and proceeded with the word "a" or "an" should be understood as not
excluding plural said elements or steps, unless such exclusion is
explicitly recited. When introducing elements/components/steps etc.
of fuel nozzle 100 and its components described and/or illustrated
herein, the articles "a", "an", "the" and "said" are intended to
mean that there are one or more of the element(s)/component(s)/etc.
The terms "comprising", "including" and "having" are intended to be
inclusive and mean that there may be additional
element(s)/component(s)/etc. other than the listed
element(s)/component(s)/etc. Furthermore, references to "one
embodiment" of the present invention are not intended to be
interpreted as excluding the existence of additional embodiments
that also incorporate the recited features.
[0089] Although the methods such as method of manufacture 700 and
method of repair 805, and articles such as primary adaptor 820,
pilot assembly 808, unitary venturi 500 described herein are
described in the context of swirling of air for mixing liquid fuel
with air in fuel nozzles in a turbine engine, it is understood that
the components, methods of manufacture and methods of repair and
assembly described herein are not limited to fuel nozzles or
turbine engines. The method of manufacture 700, method of repair
805 and repairable fuel nozzle 100 and its components, such as for
example venturi 500, illustrated in the figures included herein are
not limited to the specific embodiments described herein, but
rather, these can be utilized independently and separately from
other components described herein.
[0090] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to make and use the invention. The patentable
scope of the invention is defined by the claims, and may include
other examples that occur to those skilled in the art. Such other
examples are intended to be within the scope of the claims if they
have structural elements that do not differ from the literal
language of the claims, or if they include equivalent structural
elements with insubstantial differences from the literal languages
of the claims.
* * * * *