Patent Description:
Turbomachines are utilized in a variety of industries and applications for energy transfer purposes. For example, a gas turbine engine generally includes a compressor section, a combustion section, a turbine section, and an exhaust section. The compressor section progressively increases the pressure of a working fluid entering the gas turbine engine and supplies this compressed working fluid to the combustion section. The compressed working fluid and a fuel (e.g., natural gas) mix within the combustion section and burn in a combustion chamber to generate high pressure and high temperature combustion gases. The combustion gases flow from the combustion section into the turbine section where they expand to produce work. For example, expansion of the combustion gases in the turbine section may rotate a rotor shaft connected, e.g., to a generator to produce electricity. The combustion gases then exit the gas turbine via the exhaust section.

In some combustors, the generation of combustion gases occurs at two, axially spaced stages. Such combustors are referred to herein as including an "axial fuel staging" (AFS) system, which delivers fuel and an oxidant to one or more fuel injectors downstream of the head end of the combustor. In a combustor with an AFS system, a primary fuel nozzle at an upstream end of the combustor injects fuel and air (or a fuel/air mixture) in an axial direction into a primary combustion zone, and an AFS fuel injector located at a position downstream of the primary fuel nozzle injects fuel and air (or a second fuel/air mixture) as a cross-flow into a secondary combustion zone downstream of the primary combustion zone. The cross-flow is generally transverse to the flow of combustion products from the primary combustion zone. In some cases, it is desirable to introduce the fuel and air into the secondary combustion zone as a mixture. Therefore, the mixing capability of the AFS injector influences the overall operating efficiency and/or emissions of the gas turbine.

AFS injectors are often constructed using an additive manufacturing system, which allows for complex structural geometries and internal circuits within the injectors that otherwise would not be possible to produce. However, utilizing an additive manufacturing system to produce fuel injectors is often a high source of cost and can result in part defects. For example, additive manufacturing systems are typically limited to a certain workable area and build plate size, which puts a constraint the number of fuel injectors that may be produced at one time within the additive machine. Additionally, producing fuel injectors in an additive manufacturing system often requires numerous temporary support structures that adds additional time to the production of the part and results in increased cost.

Accordingly, an improved AFS injector having features that maximize the additive manufacturing system's workable area and build plate size, thereby increasing the amount of fuel injectors that can be produced at one time, is desired in the art. Additionally, an improved AFS injector, that minimizes the number of temporary support structures required to complete fabrication, is desired.

A method of fabricating a fuel injector is described by <CIT> and a fuel injector is also described by <CIT>.

Aspects and advantages of the fuel injectors, combustors, and methods of fabricating a fuel injector in accordance with the present disclosure will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the technology.

In accordance with an aspect of the invention as defined by the claims, a fuel injector as described in claim <NUM> is provided.

In accordance with yet another aspect of the invention as defined by the claims, a method for fabricating a fuel injector as described in claim <NUM> is provided.

These and other features, aspects and advantages of the present fuel injectors, combustors, and methods of fabricating a fuel injector will become better understood with reference to the following description and appended claims.

A full and enabling disclosure of the present fuel injectors, combustors, and methods of fabricating a fuel injector, including the best mode of making and using the present systems and methods, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:.

Reference now will be made in detail to embodiments of the present fuel injectors, combustors, and methods of fabricating a fuel injector, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation, rather than limitation of, the technology. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present technology without departing from the scope or spirit of the claimed technology. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims.

As used herein, the terms "upstream" (or "forward") and "downstream" (or "aft") refer to the relative direction with respect to fluid flow in a fluid pathway. The term "radially" refers to the relative direction that is substantially perpendicular to an axial centerline of a particular component, the term "axially" refers to the relative direction that is substantially parallel and/or coaxially aligned to an axial centerline of a particular component and the term "circumferentially" refers to the relative direction that extends around the axial centerline of a particular component. terms of approximation, such as "generally," or "about" include values within ten percent greater or less than the stated value. When used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction. For example, "generally vertical" includes directions within ten degrees of vertical in any direction, e.g., clockwise or counter-clockwise.

Referring now to the drawings, <FIG> illustrates a schematic diagram of one embodiment of a turbomachine, which in the illustrated embodiment is a gas turbine <NUM>. Although an industrial or land-based gas turbine is shown and described herein, the present disclosure is not limited to a land based and/or industrial gas turbine unless otherwise specified in the claims. For example, the invention as described herein may be used in any type of turbomachine including but not limited to a steam turbine, an aircraft gas turbine, or a marine gas turbine.

As shown, gas turbine <NUM> generally includes an inlet section <NUM>, a compressor section <NUM> disposed downstream of the inlet section <NUM>, a plurality of combustors <NUM> (<FIG>) within a combustor section <NUM> disposed downstream of the compressor section <NUM>, a turbine section <NUM> disposed downstream of the combustor section <NUM>, and an exhaust section <NUM> disposed downstream of the turbine section <NUM>. Additionally, the gas turbine <NUM> may include one or more shafts <NUM> coupled between the compressor section <NUM> and the turbine section <NUM>.

The compressor section <NUM> may generally include a plurality of rotor disks <NUM> (one of which is shown) and a plurality of rotor blades <NUM> extending radially outwardly from and connected to each rotor disk <NUM>. Each rotor disk <NUM> in turn may be coupled to or form a portion of the shaft <NUM> that extends through the compressor section <NUM>.

The turbine section <NUM> may generally include a plurality of rotor disks <NUM> (one of which is shown) and a plurality of rotor blades <NUM> extending radially outwardly from and being interconnected to each rotor disk <NUM>. Each rotor disk <NUM> in turn may be coupled to or form a portion of the shaft <NUM> that extends through the turbine section <NUM>. The turbine section <NUM> further includes an outer casing <NUM> that circumferentially surrounds the portion of the shaft <NUM> and the rotor blades <NUM>, thereby at least partially defining a hot gas path <NUM> through the turbine section <NUM>.

During operation, a working fluid such as air <NUM> flows through the inlet section <NUM> and into the compressor section <NUM> where the air <NUM> is progressively compressed, thus providing pressurized air or compressed air <NUM> to the combustors of the combustor section <NUM>. The compressed air <NUM> is mixed with fuel and burned within each combustor to produce combustion gases <NUM>. The combustion gases <NUM> flow through the hot gas path <NUM> from the combustor section <NUM> into the turbine section <NUM>, wherein energy (kinetic and/or thermal) is transferred from the combustion gases <NUM> to the rotor blades <NUM>, causing the shaft <NUM> to rotate. The mechanical rotational energy may then be used to power the compressor section <NUM> and/or to generate electricity. The combustion gases <NUM> exiting the turbine section <NUM> may then be exhausted from the gas turbine <NUM> via the exhaust section <NUM>.

<FIG> is a schematic representation of a combustor <NUM>, as may be included in a can annular combustion system for a heavy-duty gas turbine. In a can-annular combustion system, a plurality of combustors <NUM> (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more) are positioned in an annular array about the shaft <NUM> that connects a compressor to a turbine. The turbine may be operably connected (e.g., by the shaft <NUM>) to a generator for producing electrical power.

As shown in <FIG>, the combustor <NUM> may define an axial direction A and a circumferential direction C which extends around the axial direction A. The combustor <NUM> may also define a radial direction R perpendicular to the axial direction A.

In <FIG>, the combustor <NUM> includes a combustion liner <NUM> that contains and conveys combustion gases <NUM> to the turbine. The combustion liner <NUM> may have a cylindrical liner portion and a tapered transition portion that is separate from the cylindrical liner portion, as in many conventional combustion systems. Alternately, the combustion liner <NUM> may have a unified body (or "unibody") construction, in which the cylindrical portion and the tapered portion are integrated with one another. Thus, any discussion of the combustion liner <NUM> herein is intended to encompass both conventional combustion systems having a separate liner and transition piece and those combustion systems having a unibody liner. Moreover, the present disclosure is equally applicable to those combustion systems in which the transition piece and the stage one nozzle of the turbine are integrated into a single unit, sometimes referred to as a "transition nozzle" or an "integrated exit piece.

The combustion liner <NUM> is surrounded by an outer sleeve <NUM>, which is spaced radially outward of the combustion liner <NUM> to define a cooling flow annulus <NUM> between the combustion liner <NUM> and the outer sleeve <NUM>. The outer sleeve <NUM> may include a flow sleeve portion at the forward end and an impingement sleeve portion at the aft end, as in many conventional combustion systems. Alternately, the outer sleeve <NUM> may have a unified body (or "unisleeve") construction, in which the flow sleeve portion and the impingement sleeve portion are integrated with one another in the axial direction A. As before, any discussion of the outer sleeve <NUM> herein is intended to encompass both convention combustion systems having a separate flow sleeve and impingement sleeve and combustion systems having a unisleeve outer sleeve.

A head end portion <NUM> of the combustor <NUM> includes one or more fuel nozzles <NUM>. The fuel nozzles <NUM> have a fuel inlet <NUM> at an upstream (or inlet) end. The fuel inlets <NUM> may be formed through an end cover <NUM> at a forward end of the combustor <NUM>. The downstream (or outlet) ends of the fuel nozzles <NUM> extend through a combustor cap <NUM>.

The head end portion <NUM> of the combustor <NUM> is at least partially surrounded by a forward casing <NUM>, which is physically coupled and fluidly connected to a compressor discharge case <NUM>. The compressor discharge case <NUM> is fluidly connected to an outlet of the compressor <NUM> (shown in <FIG>) and defines a pressurized air plenum <NUM> that surrounds at least a portion of the combustor <NUM>. Compressed air <NUM> flows from the compressor discharge case <NUM> into the cooling flow annulus <NUM> through holes in the outer sleeve <NUM> near an aft end <NUM> of the combustor <NUM>. Because the cooling flow annulus <NUM> is fluidly coupled to the head end portion <NUM>, the compressed air <NUM> travels upstream from near the aft end <NUM> of the combustor <NUM> to the head end portion <NUM>, where the compressed air <NUM> reverses direction and enters the fuel nozzles <NUM>.

The fuel nozzles <NUM> introduce fuel and air, as a primary fuel/air mixture <NUM>, into a primary combustion zone <NUM> at a forward end of the combustion liner <NUM>, where the fuel and air are combusted. In one embodiment, the fuel and air are mixed within the fuel nozzles <NUM> (e.g., in a premixed fuel nozzle). In other embodiments, the fuel and air may be separately introduced into the primary combustion zone <NUM> and mixed within the primary combustion zone <NUM> (e.g., as may occur with a diffusion nozzle). Reference made herein to a "first fuel/air mixture" should be interpreted as describing both a premixed fuel/air mixture and a diffusion-type fuel/air mixture, either of which may be produced by fuel nozzles <NUM>.

The combustion gases from the primary combustion zone <NUM> travel downstream toward an aft end <NUM> of the combustor <NUM>. One or more fuel injectors <NUM> introduce fuel and air, as a secondary fuel/air mixture <NUM>, into a secondary combustion zone <NUM>, where the fuel and air are ignited by the primary zone combustion gases to form a combined combustion gas product stream <NUM>. Such a combustion system having axially separated combustion zones is described as an "axial fuel staging" (AFS) system, and the injector assemblies <NUM> may be referred to herein as "AFS injectors.

In the embodiment shown, fuel for each injector assembly <NUM> is supplied from the head end of the combustor <NUM>, via a fuel inlet <NUM>. Each fuel inlet <NUM> is coupled to a fuel supply line <NUM>, which is coupled to a respective injector assembly <NUM>. It should be understood that other methods of delivering fuel to the injector assemblies <NUM> may be employed, including supplying fuel from a ring manifold or from radially oriented fuel supply lines that extend through the compressor discharge case <NUM>.

<FIG> further shows that the injector assemblies <NUM> may be oriented at an angle θ (theta) relative to the center line <NUM> of the combustor <NUM>. In the embodiment shown, the leading edge portion of the injector <NUM> (that is, the portion of the injector <NUM> located most closely to the head end) is oriented away from the center line <NUM> of the combustor <NUM>, while the trailing edge portion of the injector <NUM> is oriented toward the center line <NUM> of the combustor <NUM>. The angle θ, defined between the longitudinal axis <NUM> of the injector <NUM> and the center line <NUM>, may be between <NUM> degrees and ±<NUM> degrees, between <NUM> degrees and ±<NUM> degrees, between <NUM> degrees and ±<NUM> degrees, or between <NUM> degrees and ±<NUM> degrees, or any intermediate value therebetween.

<FIG> illustrates the orientation of the injector assembly <NUM> at a positive angle relative to the center line <NUM> of the combustor. In other embodiments (not separately illustrated), it may be desirable to orient the injector <NUM> at a negative angle relative to the center line <NUM>, such that the leading edge portion is proximate the center line <NUM>, and the trailing edge portion is distal to the center line <NUM>. In one embodiment, all the injector assemblies <NUM> for a combustor <NUM>, if disposed at a non-zero angle, are oriented at the same angle (that is, all are oriented at the same positive angle, or all are oriented at the same negative angle).

The injector assemblies <NUM> inject the second fuel/air mixture <NUM> into the combustion liner <NUM> in a direction transverse to the center line <NUM> and/or the flow of combustion products from the primary combustion zone, thereby forming the secondary combustion zone <NUM>. The combined combustion gases <NUM> from the primary and secondary combustion zones travel downstream through the aft end <NUM> of the combustor can <NUM> and into the turbine section <NUM> (<FIG>), where the combustion gases <NUM> are expanded to drive the turbine <NUM>.

Notably, to enhance the operating efficiency of the gas turbine <NUM> and to reduce emissions, it is desirable for the injector <NUM> to thoroughly mix fuel and compressed gas to form the second fuel/air mixture <NUM>. Thus, the injector embodiments described below facilitate improved mixing. Additionally, because the fuel injectors <NUM> include a large number of fuel injection ports, as described further below, the ability to introduce fuels having a wide range of heat release values is increased, providing greater fuel flexibility for the gas turbine operator.

<FIG> illustrates an exemplary fuel injection assembly <NUM> in accordance with embodiments of the present disclosure. As shown, the injector assembly <NUM> may include a fuel injector <NUM> and a boss <NUM>. Although the fuel injector <NUM> and the boss <NUM> are shown in <FIG> as being two separate components coupled together, in many embodiments, the fuel injector <NUM> and the boss <NUM> may be a single integrally formed component.

As shown, the fuel injector <NUM> includes end walls <NUM> spaced apart from one another and side walls <NUM> extending between the end walls <NUM>. In many embodiments, when installed in a combustor <NUM>, the side walls <NUM> of the fuel injector <NUM> may extend parallel to the axial direction A (<FIG>). The end walls <NUM> of the fuel injector <NUM> include a forward end wall <NUM> and an aft end wall <NUM> disposed oppositely from one another. The side walls <NUM> may be spaced apart from one another and may extend between the forward end wall <NUM> and the aft end wall <NUM>. In many embodiments, both the forward end wall <NUM> and the aft end wall <NUM> are be arcuate and have a generally rounded cross-sectional shape, and the side walls may extend generally straight between the end walls <NUM>, such that the end walls <NUM> and the side walls <NUM> collectively define a first opening <NUM> having a cross section shaped as a geometric stadium. In various embodiments, the side walls <NUM> may be longer than the end walls <NUM> such that the opening <NUM> is the longest in the axial direction A when attached to the combustor <NUM>. In some embodiments, as shown, the end walls <NUM> and the side walls <NUM> may collectively define a geometric stadium shaped area, i.e. a rectangle having rounded ends, that outlines and defines a perimeter of the first opening <NUM>. In other embodiments (not shown), the end walls <NUM> may be straight such that the end walls <NUM> and the side walls <NUM> collectively define a rectangular shaped area.

In many embodiments, the first opening <NUM> may function to provide a path for compressed air <NUM> from the pressurized air plenum <NUM> to travel through and be mixed with fuel prior to reaching the secondary combustion zone <NUM>. As shown in <FIG>, the fuel injector <NUM> may further include at least one fuel injection member <NUM>, which may be disposed within the first opening <NUM> and extend axially between the end walls <NUM>. The fuel injection members <NUM> may be substantially hollow bodies that function to provide fuel to the first opening <NUM> via a plurality of fuel ports <NUM> defined through the fuel injection members <NUM>. Each of the fuel injection members may extend from a first end located at the forward end wall <NUM> to a second end positioned at the aft end wall <NUM>. In many embodiments, the fuel injection members <NUM> may be spaced apart from one another within the opening <NUM> may extend straight, i.e., without a sudden change in direction, from the forward end wall <NUM> to the aft end wall <NUM> in the axial direction A. In the embodiment shown in <FIG>, the fuel injector is shown as having two fuel injection members <NUM>. However, the fuel injector <NUM> may have any number of fuel injection members <NUM> disposed within the first opening <NUM> (e.g. <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more), and the present invention is not limited to any particular number of fuel injection members <NUM> unless specifically recited in the claims.

As shown in <FIG>, the fuel injector <NUM> further includes a conduit fitting <NUM> that is integrally formed with the forward end wall <NUM>. The conduit fitting <NUM> may be fluidly coupled to the fuel supply line <NUM> such that it receives a flow of fuel from the fuel supply line <NUM>. The conduit fitting <NUM> may then distribute fuel to each of the fuel injection members <NUM> and/or the side wall fuel injection members <NUM>, <NUM> (<FIG>) to be ejected into the first opening <NUM> and mixed with the compressed air <NUM>. As shown in <FIG>, the location and orientation of the conduit fitting <NUM> relative to the build plate <NUM> may be advantageous for the additive manufacturing system <NUM> because it prevents the conduit fitting <NUM> from having any sharp angles or overhang when being fabricated that could otherwise result in printing defects.

In many embodiments, the entire fuel injector <NUM> may be integrally formed as a single component. That is each of the subcomponents, e.g., the end walls <NUM>, the side walls <NUM>, the fuel injection members, and any other subcomponent of the fuel injector, may be manufactured together as a single body. In exemplary embodiments, this may be done by utilizing the additive manufacturing system <NUM> described herein. However, in other embodiments, other manufacturing techniques, such as casting or other suitable techniques, may be used. In this regard, utilizing additive manufacturing methods, the fuel injector <NUM> may be integrally formed as a single piece of continuous metal, and may thus include fewer sub-components and/or joints compared to prior designs. The integral formation of the fuel injector <NUM> through additive manufacturing may advantageously improve the overall assembly process. For example, the integral formation reduces the number of separate parts that must be assembled, thus reducing associated time and overall assembly costs. Additionally, existing issues with, for example, leakage, joint quality between separate parts, and overall performance may advantageously be reduced.

As shown in <FIG> and <FIG>, the fuel injector assembly <NUM> may further include a boss <NUM>. As shown, the boss <NUM> may be fixedly coupled to the combustion liner <NUM> at a first end <NUM> and may extend radially through the cooling flow annulus <NUM> to a flange portion <NUM> disposed at a second end <NUM>. The flange portion <NUM> may be substantially flat and planar, such that it provides a smooth surface for the fuel injector <NUM> to be sealingly coupled thereto, which results in no fuel/air leaks during operation of the gas turbine <NUM>. In many embodiments, the boss <NUM> may include a jacket portion <NUM> that extends between the first end <NUM> and the flange portion <NUM>.

The boss <NUM> may define a second opening <NUM> that aligns with the first opening and creates a path for fuel and air to be introduced into secondary combustion zone <NUM> (<FIG>). For example, in some embodiments, the second opening <NUM> and the first opening may share a common center axis <NUM> (<FIG> and <FIG>). In this way, the boss <NUM> provides for fluid communication between the secondary combustion zone <NUM> and the fuel injector <NUM>. More specifically, the second opening <NUM> may be defined by flange portion <NUM> and the jacket portion <NUM> of the boss <NUM> and may be shaped as a geometric stadium, i.e. a rectangle having rounded ends. In many embodiments, the size of the second opening <NUM> may vary between fuel injection assemblies <NUM> on the combustor <NUM>. For example, because the second opening <NUM> functions at least partially to meter the flow of air and fuel being introduced to the secondary combustion zone <NUM>, it may be advantageous in some embodiments to have more/less air and fuel be introduced through each one of the fuel injection assembly <NUM> on the combustor <NUM>. This may be accomplished by having increasing or decreasing the size of the second opening <NUM> depending on how much air and fuel is desired to be introduced to the secondary combustion zone <NUM>.

<FIG> illustrates a cross-sectional view of the fuel injection assembly <NUM> coupled to the combustor <NUM>. As shown in <FIG>, The jacket portion <NUM> extends from the flange <NUM>, through the cooling flow annulus <NUM>, to the combustion liner <NUM>. In many embodiments, the jacket portion <NUM> creates impediment to the flow of compressed air <NUM> through the cooling flow annulus <NUM> (<FIG>). However, as shown in <FIG>, the jacket portion <NUM> is shaped as a geometric stadium having its major axis parallel to the direction of the compressed air <NUM> flow. This advantageously produces a smaller compressed air <NUM> blockage in the cooling flow annulus <NUM> than, for example, a jacket portion having a round shape, while still providing an adequate area for enough fuel and air to be introduced through the second opening <NUM> and into the secondary combustion zone <NUM>.

In many embodiments, as shown, the side walls <NUM> may include a first side wall fuel injection member <NUM> and a second side wall fuel injection member <NUM>. For example, the side wall fuel injection members <NUM>, <NUM> may be integrally formed within the side walls <NUM>, such that they function to both partially define the first opening <NUM> and inject fuel through the plurality of fuel ports <NUM> for mixing within the fuel injector <NUM>. In various embodiments, as shown, the fuel injection members <NUM> may be a third fuel injection member <NUM> and a fourth fuel injection member <NUM>. In many embodiments, there may be six injection planes within the fuel injector <NUM>. For example, a single row of fuel ports <NUM> may be defined on both the side wall fuel injection members <NUM>, <NUM>, which provides for two of the fuel injection planes. Four more fuel injection planes may be disposed on the fuel injection members <NUM>, <NUM>. For example, each fuel injection member <NUM>, <NUM> may have a single row of fuel ports <NUM> disposed on either side of the fuel injection members <NUM>, <NUM>, which provides four fuel injection planes. In some embodiments, the first side wall fuel injection member <NUM> and the second side wall fuel injection member <NUM> may converge towards one another as they extend radially inward. In this way, the entire geometric stadium area defined by the end walls <NUM> and the side walls <NUM> gradually reduces as the fuel injector <NUM> extends radially inward.

As shown in <FIG>, the fuel injection members <NUM>, <NUM> may each have an exterior cross-sectional profile <NUM> defining a teardrop shape. As shown, the teardrop shape is characterized as having a leading edge <NUM>, a trailing edge <NUM> opposite the leading edge <NUM>, and walls <NUM>. The walls <NUM> may extend between the leading edge <NUM> and the trailing edge <NUM>. In many embodiments, the walls <NUM> of each fuel injection member <NUM>, <NUM> defines the plurality of fuel injection ports <NUM>. In at least one embodiment, the fuel injection ports <NUM> may be disposed in a single row (<FIG>). As shown in <FIG> collectively, the exterior cross-sectional profile <NUM> of the fuel injection members <NUM>, <NUM> may be uniform in the axial direction A, such that there is no sudden change in shape or orientation as they extend in the axial direction A from the forward end wall <NUM> to the aft end wall <NUM>. Although the fuel injection members <NUM>, <NUM> are shown in <FIG> as having an exterior cross sectional profile <NUM> that defines a teardrop shape, the fuel injection members <NUM>, <NUM> may each have an exterior cross-sectional profile defining any one of a circular shape, triangular shape, diamond shape, rectangular shape, or any other suitable cross sectional shape.

As shown in <FIG>, the fuel injector <NUM> may further include an injection axis <NUM> disposed in the center of the first opening <NUM>. The injection axis <NUM> may be parallel to the radial direction R when the fuel injector is connected to a combustor <NUM>. In many embodiments, the side walls may converge towards the injection axis <NUM> in the downstream direction with respect to the direction of air flow through the fuel injector <NUM>.

<FIG> illustrates a plan view of the fuel injection assembly <NUM>, showing a fuel circuit <NUM> defined within the fuel injector <NUM> in dotted lines. As shown, the fuel circuit <NUM> may be fluidly coupled to the fuel supply line <NUM> via the conduit fitting <NUM>. In many embodiments, the fuel circuit includes <NUM> inlet plenum <NUM> defined within the forward end wall <NUM> of the fuel injector <NUM>. The inlet plenum <NUM> may receive fuel from the fuel supply line <NUM> and distribute it to one or more fuel passages <NUM> defined within the side wall fuel injection members <NUM>, <NUM> and/or the fuel injection members <NUM>, <NUM>. In some embodiments, as shown in <FIG>, each of the fuel passages <NUM> may extend directly from the inlet fuel plenum <NUM>, along the axial direction A, to the aft end wall <NUM>. In many embodiments, each of the fuel passages <NUM> may be parallel to one another. As shown in <FIG> the plurality of fuel ports <NUM> may be defined on the side wall fuel injection members <NUM>, <NUM> and/or the fuel injection members <NUM>, <NUM> and in fluid communication with the respective fuel passages <NUM>, in order to provide fuel to the first opening <NUM> to be mixed with compressed air <NUM> before entering the secondary combustion zone <NUM>. For example, in many embodiments, each fuel port <NUM> of the plurality of fuel ports <NUM> may extend between a respective fuel passage <NUM> and the opening <NUM>.

As shown in <FIG>, the fuel injector <NUM> may further include a longitudinal axis <NUM> that extends across the center of the first opening <NUM> of the fuel injector <NUM>. As shown in <FIG>, the first sidewall fuel injection member <NUM> and the third fuel injection member <NUM> may be disposed on a first side of the longitudinal axis <NUM>, and the second sidewall fuel injection member <NUM> and the fourth fuel injection member <NUM> may be disposed on a second side of the longitudinal axis <NUM>. In many embodiments, the longitudinal axis <NUM> may be parallel to the axial direction A when the fuel injector <NUM> is connected to the combustor <NUM>.

In many embodiments, the fuel injector <NUM> may further include a first connecting member <NUM> that extends away from the forward end wall <NUM> and a second connecting member <NUM> that extends away from the aft end wall <NUM>. As shown in <FIG>, the first connecting member. More specifically, the first connecting member <NUM> may extend away from a corner <NUM> of the fuel injector that is disposed at the intersection of the first sidewall fuel injection member <NUM> and the forward end wall <NUM>. Similarly, the second connecting member <NUM> may extend away from a corner <NUM> disposed at the intersection of the second sidewall fuel injection member <NUM> and the aft end wall <NUM>. In this way, the first connecting member <NUM> and the second connecting member <NUM> may be disposed on opposite sides of the longitudinal axis <NUM>, in order to provide support to the fuel injector <NUM> in all directions when mounted to the boss <NUM>. In many embodiments, each of the connecting members <NUM>, <NUM> may define a faster hole that is sized to receive a mechanical fastener <NUM> therethrough, which couples the fuel injector <NUM> to the boss <NUM>.

To illustrate an example of an additive manufacturing system and process, <FIG> shows a schematic/block view of an additive manufacturing system <NUM> for generating an object <NUM>, such as the fuel injector <NUM> described herein. <FIG> may represent an additive manufacturing system configured for direct metal laser sintering (DMLS) or direct metal laser melting (DMLM). The additive manufacturing system <NUM> builds objects, for example, the object <NUM>, in a layer-by-layer manner by sintering or melting a powder material (not shown) using an energy beam <NUM> generated by a source such as a laser <NUM>. The powder to be melted by the energy beam is supplied by reservoir <NUM> and spread evenly over a build plate <NUM> using a recoater arm <NUM> to maintain the powder at a level <NUM> and remove excess powder material extending above the powder level <NUM> to waste container <NUM>. The energy beam <NUM> sinters or melts a cross sectional layer of the object being built under control of the galvo scanner <NUM>. The build plate <NUM> is lowered and another layer of powder is spread over the build plate and the object being built, followed by successive melting/sintering of the powder by the laser <NUM>. The process is repeated until the object <NUM> is completely built up from the melted/sintered powder material. The laser <NUM> may be controlled by a computer system including a processor and a memory. The computer system may determine a scan pattern for each layer and control laser <NUM> to irradiate the powder material according to the scan pattern. After fabrication of the object <NUM> is complete, various post-processing procedures may be applied to the object <NUM>. Post processing procedures include removal of excess powder by, for example, blowing or vacuuming. Other post processing procedures include a stress release process. Additionally, thermal and chemical post processing procedures can be used to finish the object <NUM>.

<FIG> illustrate various views of a build plate assembly <NUM> in which multiple fuel injectors <NUM> are attached to a build plate <NUM>. The fuel injectors <NUM> illustrated in <FIG> have been fabricated onto the build plate <NUM> using an additive manufacturing system, such as the additive manufacturing system <NUM> described herein. As shown, the fuel injectors <NUM> are still attached to a build plate <NUM> and have not undergone any post-machining or post processing procedures. In many embodiments, the fuel injectors <NUM> may be fixedly connected to the build plate <NUM>, such that they may be machined off the build plate before being assembled onto the combustor <NUM>.

Numerous features of the fuel injector <NUM> described herein advantageously improve the efficiency in which the fuel injector is additively manufactured. This may allow for faster production, fewer errors during fabrication, and overall cost savings. The features of the fuel injector <NUM>, and the orientation of the fuel injector <NUM> on the build plate <NUM>, favorably allow for the maximum number of fuel injectors per workable area, which allows for more efficient production of the fuel injector <NUM>. For example, in <FIG>, the workable area <NUM> is indicated by the dotted lines surrounding the fuel injectors <NUM> in the build plate assembly <NUM>. The workable area <NUM> shows the area in which the additive manufacturing system <NUM> is capable of operating, which is at least partially dependent on the particular additive machine and build plate size. Therefore, maximizing the number of fuel injectors <NUM> for a particular build plate and workable area increases the rate of production and cost savings. For example, in the embodiments shown in <FIG>, the features of the fuel injector <NUM> allow for six fuel injectors to be manufactured at a time on a single build plate <NUM>. Although the embodiments shown in <FIG> illustrate six fuel injectors attached to the build plate <NUM>, other embodiments may include more or less depending on the size of the build plate and workable area. In this way, the features and orientation of the fuel injector <NUM> is fully scalable depending on the size of the build plate <NUM> and the workable area <NUM>. For example, larger build plates may allow for <NUM>, <NUM>, <NUM>, or upwards of <NUM> fuel injectors to be produced at a time, and the present invention should not be limited to the number of fuel injectors fabricated on the build plate unless specifically recited in the claims.

As shown in <FIG>, the build plate assembly <NUM> may include one or more temporary supports <NUM> (shown in dotted lines), which function to provide temporary support to the fuel injector <NUM> while it is being fabricated on the build plate <NUM>. The temporary supports <NUM> may then be removed prior to installation of the fuel injector <NUM> in the combustor <NUM>. In many embodiments, it may be advantageous to minimize the number and/or amount of temporary supports <NUM> necessary to produce a fuel injector <NUM>, at least because it reduces the amount of material used during the fabrication which reduces cost. As described above, the second connecting member <NUM> extends away from the aft end wall <NUM>, which allows it to be directly coupled to the build plate <NUM>, as shown, during the additive manufacturing process, thereby reducing the number of removable supports <NUM> necessary and increasing production cost savings. In addition, having the first connecting member <NUM> and the second connecting member <NUM> extend away from the end walls <NUM>, instead of, e.g. the side walls <NUM>, allows for more room on the build plate <NUM> to fit more fuel injectors <NUM>.

As shown in <FIG> and <FIG>, the longitudinal axis <NUM> of each of the fuel injectors <NUM> may form an angle <NUM> with the build plate <NUM> that is oblique, i.e. not parallel or perpendicular. For example, in some embodiments, the angle <NUM> may be between about <NUM>° and about <NUM>°. In other embodiments, the angle <NUM> may be between about <NUM>° and about <NUM>°. In various embodiments, the angle <NUM> may be between about <NUM>° and about <NUM>°. In particular embodiments, the angle <NUM> may be between about <NUM>° and about <NUM>°. The angle <NUM> between the longitudinal axis of the fuel injector <NUM> and the build plate <NUM> may be advantageous for many reasons. For example, the angle <NUM> may prevent excess powder from building up on the part during the additive manufacturing process. In addition, the angle <NUM> may allow for the complex fuel circuit <NUM> to be additively manufactured without collapsing due to weight of the fuel injector during the printing process. In many embodiments, the angle <NUM> allows the fuel injector <NUM> to be additively manufactured without running into any features that could otherwise be problematic to additively manufacture. For example, the angle <NUM> may advantageously prevent features of the fuel injector <NUM> from overhanging while being fabricated, which may otherwise result in distortion of the part.

In many embodiments, as shown in <FIG>, the forward end wall <NUM> and the aft end wall <NUM> may be curve as they extend between the side walls <NUM>, which may provide numerous advantageous for being fabricated on the additive manufacturing system <NUM>. As shown, when attached to the build plate <NUM>, the forward end wall <NUM> may be generally concave, i.e., the forward end wall <NUM> may rounded inward (towards the build plate). Similarly, when attached to the build plate <NUM>, the aft end wall <NUM> may be generally convex, i.e., rounded outward (away from the build plate). Utilizing end walls <NUM> that are curved, rounded, and/or arcuate advantageously allows the additive manufacturing system <NUM> to fabricate the end walls <NUM> at an angle, thereby preventing unwanted overhang during the production process.

<FIG> is a flow chart of a sequential set of steps <NUM> through <NUM>, which define a method <NUM> of fabricating a fuel injector <NUM>, in accordance with embodiments of the present disclosure. The method <NUM> may be performed using an additive manufacturing system, such as the additive manufacturing system <NUM> described herein or another suitable system. As shown in <FIG>, the method <NUM> includes a step <NUM> of irradiating a layer of powder in a powder bed <NUM> to form a fused region. In many embodiments, the powder bed may be disposed the build plate <NUM>, such that the fused region is fixedly attached to the build plate <NUM>. The method <NUM> may include a step <NUM> of providing a subsequent layer of powder over the powder bed <NUM> from a first side of the powder bed <NUM>. The method <NUM> further includes a step <NUM> of repeating steps <NUM> and <NUM> until the fuel injector <NUM> is formed on the build plate <NUM>.

<FIG> illustrates a cross section of a fuel injector <NUM> taken from along the injection axis <NUM> (See <FIG>). As shown in <FIG>, the forward end wall <NUM>, the aft end wall <NUM>, the first side wall fuel injection member <NUM>, and the second side wall fuel injection member <NUM> each define respective interior surfaces <NUM>, <NUM>, <NUM>, and <NUM> that collectively encompass the opening <NUM>, such that the interior surfaces, <NUM>, <NUM>, <NUM>, <NUM> collectively define the boundary of the opening <NUM>. As shown in <FIG>, the opening <NUM> includes a major axis <NUM> and a minor axis <NUM>. In exemplary embodiments, the major axis <NUM> aligns with the longitudinal axis <NUM> (<FIG>) and extends between the interior surface <NUM> of the forward end wall <NUM> and the interior surface <NUM> of the aft end wall <NUM>. The minor axis <NUM> may be perpendicular to both the major axis <NUM> and the injection axis <NUM>, and the minor axis <NUM> may extend between the interior surface <NUM> of the first side wall fuel injection member <NUM> and the interior surface <NUM> of the second side wall fuel injection member <NUM>. In various embodiments, the major axis <NUM> may be longer than the minor axis <NUM>.

As shown in <FIG>, the first opening <NUM> may be generally shaped as a geometric stadium, i.e. a rectangle having rounded ends. For example, the interior surfaces <NUM> and <NUM> of the side wall fuel injection members <NUM>, <NUM> may extend straight, parallel to the major axis <NUM>, between the interior surface <NUM> of the forward end wall <NUM> and the interior surface <NUM> of the aft end wall <NUM>. Additionally, the interior surfaces <NUM> and <NUM> of the forward end wall <NUM> and the aft end wall <NUM> are generally curved or arcuate. The interior surface <NUM> of the forward end wall <NUM> diverges away from the minor axis <NUM> from the interior surface <NUM> of the first side wall fuel injection member <NUM> to the major axis <NUM>, and the interior surface <NUM> of the forward end wall <NUM> converges towards the minor axis <NUM> from the major axis <NUM> to the interior surface <NUM> of the second side wall fuel injection member <NUM>. Similarly, the interior surface <NUM> of the aft end wall <NUM> diverges away from the minor axis <NUM> from the interior surface <NUM> of the first side wall fuel injection member <NUM> to the major axis <NUM>, and the interior surface <NUM> of the aft end wall <NUM> converges towards the minor axis <NUM> from the major axis <NUM> to the interior surface <NUM> of the second side wall fuel injection member <NUM>.

As shown in <FIG> and <FIG>, the fuel injector <NUM> may have a shape that generally corresponds with the contour or shape of the opening <NUM>, which advantageously provides multiple benefits when additively manufacturing the fuel injector <NUM>. For example, the advanced geometric shape of the fuel injector <NUM> shown and described herein advantageously facilitates the additive manufacturing of the fuel injector <NUM> without defects, especially when fabricated on the build plate <NUM> in the position shown in <FIG>. For example, the end walls <NUM> being generally arcuate or curved in the manner described herein advantageously facilitates additive manufacturing of the fuel injector <NUM> without causing overhang, which could otherwise result in printing defects or a total collapse of the fuel injector <NUM> on the build plate <NUM>.

Claim 1:
A method for fabricating a fuel injector (<NUM>), comprising:
irradiating a layer of powder in a powder bed (<NUM>) to form a fused region, the powder bed (<NUM>) disposed on a build plate (<NUM>);
providing a subsequent layer of powder over the powder bed (<NUM>) by passing a recoater arm (<NUM>) over the powder bed (<NUM>) from a first side of the powder bed (<NUM>); and
repeating steps the irradiating step and the providing step until the fuel injector (<NUM>) is formed on the build plate (<NUM>), wherein the fuel injector (<NUM>) comprises:
a forward end wall (<NUM>) and an aft end wall (<NUM>) disposed oppositely from one another;
side walls (<NUM>) extending between the forward end wall (<NUM>) and the aft end wall (<NUM>), wherein the forward end wall (<NUM>) and the aft end wall (<NUM>) are arcuate, and wherein the forward end wall (<NUM>), the aft end wall (<NUM>), and the side walls (<NUM>) collectively define an opening (<NUM>) for passage of air, wherein the forward end wall (<NUM>), the aft end wall (<NUM>), and the side walls (<NUM>) each define a respective interior surface that collectively provide a boundary for the opening (<NUM>), wherein the opening (<NUM>) comprises a major axis (<NUM>) and a minor axis (<NUM>), and wherein the interior surface (<NUM>) of the forward end wall (<NUM>) and the interior surface (<NUM>) of the aft end wall (<NUM>) diverge away from the minor axis (<NUM>) from a first side wall of the side walls (<NUM>) to the major axis (<NUM>) and converge towards the minor axis (<NUM>) from the major axis (<NUM>) to a second side wall of the side walls (<NUM>);
at least one fuel injection member (<NUM>) disposed within the opening (<NUM>) and extending between the forward end wall (<NUM>) and the aft end wall (<NUM>)
an injection axis (<NUM>) defined through the center of the opening (<NUM>) and a longitudinal axis (<NUM>) perpendicular to the injection axis (<NUM>), wherein the longitudinal axis (<NUM>) of the fuel injector (<NUM>) forms an angle with the build plate (<NUM>) that is oblique.