CROSS-REFERENCE TO RELATED APPLICATIONS 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 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.
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° F. (1920° 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.
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.
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.
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.
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.
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.
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 The above-mentioned need or needs may be met by exemplary embodiments which provide a method of repairing a fuel nozzle comprising the steps of: forming a pilot assembly; installing into a repair bore; inserting a primary adaptor into a repair bore such that the primary adaptor is in flow communication with a pilot flow passage and the pilot assembly; and coupling the primary adaptor to a distributor and the new pilot assembly.
BRIEF DESCRIPTION OF THE DRAWINGS 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:
FIG. 1 is a partial cross-sectional view of exemplary repairable fuel nozzle according to an exemplary embodiment of the present invention.
FIG. 2 is an axial cross sectional view of the tip region of the exemplary repairable fuel nozzle shown in FIG. 1.
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.
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.
FIG. 5 an axial cross-sectional view of the tip region of an exemplary fuel nozzle with some components drilled out.
FIG. 6 is a top plan view of an exemplary fuel swirler having a braze-groove.
FIG. 7 is an axial cross-sectional view of an exemplary primary pilot assembly.
FIG. 8 is an axial cross-sectional view of an exemplary new pilot assembly placed on a test fixture for flow testing.
FIG. 9 is a schematic view of an X-ray inspection of a new pilot assembly.
FIG. 10 is a schematic view of assembling a braze wire in braze-groove in a new pilot assembly.
FIG. 11 is an axial cross-sectional view of the tip region of an exemplary fuel nozzle during reassembly as part of repair.
FIG. 12 is an axial cross sectional view of an exemplary primary adaptor and braze wires.
FIG. 13 is an axial cross-sectional view of the tip region of an exemplary fuel nozzle during reassembly as part of repair.
FIG. 14 is an axial cross-sectional view of the tip region of an exemplary fuel nozzle after repair.
FIG. 15 is an isometric view of an exemplary venturi having exemplary damage.
FIG. 16 is a flow chart showing an exemplary method of repairing a damaged heat-shield.
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.
FIG. 18 is a side view of a damaged venturi heat-shield being repaired by an exemplary method of the present invention.
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 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.
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.
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.
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.
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 1 1.
The term “unitary” is used in this application to denote that the associated component, such, for example, as the venturi 500 described herein, is made as a single piece during manufacturing. Thus, a unitary component has a monolithic construction for the component.
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.
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.
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.
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.
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 FIGS. 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.
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.
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.
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.
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.
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.
The venturi 500 comprises a heat shield 540 for protecting venturi and other components in the fuel nozzle tip assembly 68 (see FIG. 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.
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.
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.
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.
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 FIGS. 14 may be made integrally to have a unitary construction using the DMLS method.
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.
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.
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.RTM. M 270 DMLS machine, a PHENIX PM250 machine, and/or an EOSINT.RTM. 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.
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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. 11. 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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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%.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
