Fuel injection device for combustor

Abstract

To provide a fuel injection assembly and a combustor.SOLUTION: A fuel injection assembly (80) includes a boss (300) that forms at least a portion of an annular wall (308). The annular wall (308) defines a mixing channel (312) that extends along a center axis (350). The fuel injection assembly (80) further includes a fuel injection device (200) that has a radially outer wall (220) and a radially inner wall (222) that at least partially define a fuel plenum (224). The fuel injection device (200) further includes a plurality of premix tubes (226) that each extend along an injection axis (228) from an inlet end (230) on the radially outer wall (220) through the fuel plenum (224) to an outlet end (232), and the injection axis (228) of each of the premix tubes (226) is slanted towards the center axis (350) of the mixing channel (312).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to fuel injectors for gas turbine combustors, and more specifically to fuel injectors used in axial fuel staging (AFS) systems associated with such combustors. [Background technology]

[0002] Turbomachines are utilized in various industries and applications for energy transfer. For example, a gas turbine engine typically 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 the compressed working fluid to the combustion section. The compressed working fluid and a fuel (such as natural gas) are mixed in the combustion section and combusted in a combustion chamber to generate high-pressure, high-temperature combustion gases. The combustion gases flow from the combustion section to the turbine section, where they expand to produce work. For example, the expansion of the combustion gases in the turbine section rotates a rotor shaft connected to, for example, an electrical generator. The combustion gases are then exhausted from the gas turbine through the exhaust section.

[0003] In some combustors, generation of combustion gases occurs in two axially spaced stages. Such combustors, referred to herein as including an "axial fuel staging" (AFS) system, deliver fuel and oxidizer to one or more fuel injectors downstream of the combustor head end. In an AFS type combustor, a main fuel nozzle upstream of the combustor injects fuel and air (or a fuel and air mixture) axially into a primary combustion zone, and AFS fuel injectors located downstream of the main fuel nozzle inject a fuel and air (or a second fuel and air mixture) in a crossflow into a secondary combustion zone downstream of the main combustion zone. The crossflow is generally transverse to the flow of combustion products from the primary combustion zone.

[0004] A conventional gas turbine engine includes one or more combustors that combust a mixture of natural gas and air in a combustion chamber to produce high pressure and high temperature combustion gases. As by-products, nitrogen oxides (NOx) and other pollutants are produced and emitted through an exhaust section. Regulatory requirements for low emissions from gas turbines are becoming increasingly stringent, and environmental agencies around the world are demanding further reductions in emission rates of NOx and other pollutants from both new and existing gas turbines.

[0005] Combustion of mixtures of natural gas and large amounts of hydrogen and / or burning pure hydrogen instead of natural gas in a combustor significantly reduces or eliminates emissions of NOx and other pollutants. However, because hydrogen has different combustion characteristics than natural gas, high concentrations of hydrogen and / or pure hydrogen cannot be safely burned in conventional combustion systems, including conventional AFS fuel injectors. For example, burning high concentrations of hydrogen and / or pure hydrogen in conventional combustion systems can promote flashback or flame holding conditions, in which the combustion flame moves toward the fuel delivered by the injectors, which can cause severe damage to the injectors in a relatively short period of time.

[0006] Thus, there is a need in the art for a fuel injection assembly that can deliver alternative fuels (such as hydrogen) and air to the secondary combustion zone without causing flame holding or flashback problems. Summary of the Invention

[0007] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a fuel injection assembly and a combustor according to the present disclosure; FIG. 2 is a block diagram of a fuel injection assembly and a combustor according to the present disclosure;

[0008] In one embodiment, a fuel injection assembly for a combustor of a gas turbine is provided. The fuel injection assembly includes a fuel injector configured to couple to an outer sleeve of the combustor. The fuel injection assembly further includes a boss spaced from the fuel injector and configured to couple to a combustion liner of the combustor. The boss includes a flange portion, an annular wall portion extending from the flange portion, and an inner surface. The boss defines a serpentine cooling passage extending from an inlet in the flange portion to an outlet on the inner surface.

[0009] In another embodiment, a combustor is provided. The combustor includes one or more fuel nozzles and a combustion liner extending downstream from the fuel nozzles. The combustor further includes an outer sleeve spaced apart from and surrounding the combustion liner to define an annulus between the combustor and the outer sleeve. The combustor further includes a fuel injection assembly disposed downstream from the one or more fuel nozzles. The fuel injection assembly includes a fuel injector configured to couple to the outer sleeve of the combustor. The fuel injection assembly further includes a boss spaced apart from the fuel injector and configured to couple to the combustion liner of the combustor. The boss includes a flange portion, an annular wall portion extending from the flange portion, and an inner surface. The boss defines a serpentine cooling passage extending from an inlet in the flange portion to an outlet on the inner surface.

[0010] In yet another embodiment, a fuel injection assembly for a combustor of a gas turbine is provided. The fuel injection assembly includes a fuel injector configured to couple to an outer sleeve of the combustor. The fuel injection assembly further includes a boss spaced from the fuel injector and configured to couple to a combustion liner of the combustor. The boss has a flange portion and an annular wall portion extending from the flange portion. The annular wall portion includes a first end segment, a second end segment, and a side segment extending between the first end segment and the second end segment. The boss includes a first closure flange extending from the first end segment and a second closure flange extending from the second end segment.

[0011] In another embodiment, a fuel injection assembly for a combustor of a gas turbine is provided. The fuel injection assembly includes a boss forming at least a portion of an annular wall. The annular wall defines a mixing passage extending along a central axis. The fuel injection assembly further includes a fuel injector having a radially outer wall and a radially inner wall at least partially defining a fuel plenum. The fuel injector further includes a plurality of premixer tubes each extending along an injection axis from an inlet end on the radially outer wall through the fuel plenum to an outlet end, the injection axis being angled toward the central axis of the mixing passage.

[0012] In yet another embodiment, a combustor is provided. The combustor includes at least one fuel nozzle and a combustion liner extending downstream from the fuel nozzle. The combustor further includes an outer sleeve spaced apart from and surrounding the combustion liner to define an annulus between the combustion liner and the outer sleeve. The combustor further includes a fuel injection assembly disposed downstream from the at least one fuel nozzle. The fuel injection assembly includes a boss forming at least a portion of an annular wall. The annular wall defines a mixing passage extending along a central axis. The fuel injection assembly further includes a fuel injector having a radially outer wall and a radially inner wall that at least partially define a fuel plenum. The fuel injector further includes a plurality of premixer tubes each extending along an injection axis from an inlet end on the radially outer wall through the fuel plenum to an outlet end, the injection axis being angled toward a central axis of the mixing passage.

[0013] These and other features, aspects, and advantages of the present fuel injection assembly and combustor will become better understood with reference to the following detailed description and claims. The accompanying drawings, which form a part of the present specification, illustrate various embodiments of the disclosed technology and, together with the detailed description, serve to explain the principles of the technology. [Brief description of the drawings]

[0014] The present fuel injection assembly and combustor, when taken in conjunction with the accompanying drawings, will now be described in detail in a detailed manner sufficient to enable those skilled in the art to practice the present invention, including the best mode of making and using the present systems and methods.

[0015] [Figure 1] 1 is a schematic diagram of a turbomachine according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram of a combustor that may be used in the turbomachine of FIG. 1 in accordance with an embodiment of the present disclosure. [Diagram 3] FIG. 2 is an enlarged perspective view of a portion of a combustor having a fuel injection assembly according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a cross-sectional view of the combustor shown in FIG. 3 taken along line 4-4 according to an embodiment of the present disclosure. [Diagram 5] FIG. 5 is a cross-sectional view of the combustor shown in FIG. 3 taken along line 5-5. [Figure 6] FIG. 2 is a cross-sectional perspective view of a portion of a combustor having a fuel injection assembly according to an embodiment of the present disclosure. [Figure 7] 7 is a plan view of the fuel injection device shown in FIG. 6 taken along line 7-7 according to the embodiment of the present disclosure. [Figure 8] FIG. 2 is a perspective view of a boss of a fuel injection assembly according to an embodiment of the present disclosure. [Figure 9] FIG. 9 is a top down plan view of a boss of the fuel injection assembly of FIG. 8 in accordance with an embodiment of the present disclosure. [Figure 10] FIG. 9 is a perspective view of a boss of the fuel injection assembly of FIG. 8 in accordance with an embodiment of the present disclosure. [Figure 11] FIG. 11 is an enlarged cross-sectional view of a portion of a boss coupled to the combustion liner of FIGS. 8-10 that defines a first serpentine cooling passage in accordance with an embodiment of the present disclosure. [Figure 12] FIG. 11 is an enlarged cross-sectional view of a portion of a boss coupled to the combustion liner of FIGS. 8-10 that defines a second serpentine cooling passage in accordance with an embodiment of the present disclosure. [Figure 13] 13 is an enlarged plan view of the boss shown in FIG. 12 taken along line 13-13 according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Various embodiments of the present fuel injection assembly and combustor are described in detail below, one or more examples of which are illustrated in the drawings. The embodiments are intended to be illustrative, rather than limiting, of the present technology. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made in the present technology without departing from the scope or spirit of the technology as set forth in the appended claims. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Accordingly, the present disclosure covers modifications and variations that come within the scope of the appended claims and their equivalents.

[0017] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Moreover, unless otherwise specified, all embodiments described herein are to be construed as illustrative.

[0018] In the detailed description of the invention, numerical and letter designations are used to refer to features depicted in the drawings. In the drawings and the detailed description of the invention, like or similar designations indicate like or similar components of the invention. In this specification, the terms "first," "second," and "third" are used interchangeably to distinguish one component from another, and do not imply a position or importance of the individual components.

[0019] The term "fluid" may refer to either a gas or a liquid. The term "fluid communication" means the ability to flow or transmit a fluid between given areas.

[0020] As used herein, the terms "upstream" (or "forward") and "downstream" (or "aft") refer to relative directions with respect to fluid flow in a fluid pathway. For example, "upstream" refers to the direction from which fluid flows and "downstream" refers to the direction to which fluid flows. The term "radial" refers to a relative direction that is substantially perpendicular to an axial centerline of a part, the term "axial" refers to a relative direction that is substantially parallel and / or coaxial to an axial centerline of a part, and the term "circumferential" refers to a relative direction about the axial centerline of a part.

[0021] Approximate terms such as "about," "approximately," and "substantially" are not limited to the exact numerical values ​​stated. In at least some cases, the approximation corresponds to the precision of an instrument that measures the value or the precision of a method or machine for constructing or manufacturing the part and / or system. In at least some cases, the approximation corresponds to the precision of an instrument that measures the value or the precision of a method or machine for constructing or manufacturing the part and / or system. For example, the approximation may refer to an error within 1%, 2%, 4%, 5%, 10%, 15%, or 20% of any of the individual numerical values, numerical ranges, and / or upper and lower limits used to define the numerical ranges. When used in relation to angles or directions, such terms include within ±10 degrees of the stated angle or direction. For example, "approximately vertical" includes a direction within 10 degrees in any direction (e.g., clockwise or counterclockwise) from vertical.

[0022] Terms such as "coupled," "fixed," or "attached" refer to direct coupling, fixing, or attachment, as well as indirect coupling, fixing, or attachment through one or more intermediate parts or features, unless otherwise stated herein. Terms such as "directly coupled," "directly fixed," and "directly attached" refer to a first component being joined to a second component without an intervening structure. As used herein, the terms "including," "comprising," and "having" are intended to include non-exclusive inclusions. For example, a process, method, article, or device that includes recited features is not necessarily limited to those features, and may include other features not expressly recited or inherent to such process, method, article, or device. Furthermore, unless otherwise stated, the term "or" refers to an inclusive selection, not an exclusive selection. For example, a condition A or B is true if A is true (or present) and B is false (or absent), or if A is false (or absent) and B is true (or present).

[0023] In the present specification and claims, ranges of numerical limitations include all subranges contained therein unless otherwise stated or apparent from the context, for example, all ranges disclosed herein are inclusive and the limits are independently combinable with each other.

[0024] As used herein, the term "premixed" may be used to describe a component, passage, or cavity upstream of a respective combustion zone in which mixing occurs. For example, "premixed" may be used to describe a component, passage, or cavity in which two fluids (such as fuel and air) are mixed together before being discharged from such component, passage, or cavity (e.g., into the combustion zone).

[0025] Referring now to the drawings, Figure 1 illustrates a schematic diagram of one embodiment of a turbomachine, which in the illustrated embodiment is a gas turbine engine 10. Although an industrial or land-based gas turbine is described and illustrated herein, the present disclosure is not limited to land and / or industrial gas turbine engines unless otherwise recited in the claims. For example, the techniques described herein may be used with any type of turbomachine, including, but not limited to, a steam turbine, an aircraft gas turbine, or a marine gas turbine.

[0026] As shown in the figures, the gas turbine engine 10 generally includes an intake section 12, a compressor section 14 disposed downstream from the intake section 12, a number of combustors 17 (see FIG. 2 ) in a combustor section 16 disposed downstream from the compressor section 14, a turbine section 18 disposed downstream from the combustor section 16, and an exhaust section 20 disposed downstream from the turbine section 18. Additionally, the gas turbine engine 10 may include one or more shafts 22 coupled between the compressor section 14 and the turbine section 18.

[0027] The compressor section 14 generally includes a number of rotor disks 24 (one shown) and a number of rotor blades 26 extending radially outwardly from and connected to each rotor disk 24. Each rotor disk 24 is coupled to or forms part of a shaft 22 that extends through the compressor section 14. The compressor section 14 also includes a number of stator vanes (not shown) that are arranged in stages with the rotor blades 26 to direct flow to the rotor blades 26.

[0028] The turbine section 18 generally includes a number of rotor disks 28 (one shown) and a number of rotor blades 30 extending radially outward from and connected to each rotor disk 28. Each rotor disk 28 is coupled to or forms part of a shaft 22 that extends through the turbine section 18. The turbine section 18 further includes an outer casing 31 that circumferentially surrounds the shaft 22 and a portion of the rotor blades 30 and at least partially defines a hot gas path 32 through the turbine section 18. The turbine section 18 also includes a number of stator vanes (not shown) that are arranged in stages with the rotor blades 30 to direct flow to the rotor blades 30.

[0029] During operation, a working fluid, such as air, enters the intake section 12 into the compressor section 14 where the air is progressively compressed by multiple compressor stages of rotor blades and stator vanes to provide compressed air to combustors 17 in the combustor section 16. The compressed air is mixed with fuel and combusted in each combustor to generate combustion gases 34. The combustion gases 34 flow from the combustor section 16 through a hot gas path 32 into the turbine section 18 where energy (kinetic and / or thermal) is transferred from the combustion gases 34 to the rotor blades 30 to rotate the shaft 22. The mechanical rotational energy may then be used to drive the compressor section 14 and / or to generate electricity. The combustion gases 34 exiting the turbine section 18 may then exit the gas turbine engine 10 via the exhaust section 20.

[0030] 2 is a schematic diagram of a combustor 17 that may be included in a cannular combustion system 16 for a gas turbine 10. In a cannular combustion system, multiple (e.g., 8, 10, 12, 14, 16 or more) combustors 17 are arranged in an annular array about a shaft 22 that connects the compressor section 14 to the turbine section 18.

[0031] 2, the combustor 17 may define an axial direction A extending along an axial centerline 170. The combustor may also define a circumferential direction C extending about the axial direction A and the axial centerline 170. The combustor 17 may further define a radial direction R that is perpendicular to the axial direction A and the axial centerline 170.

[0032] As shown in FIG. 2, the combustor 17 includes a combustion liner 46 that defines a combustion chamber 70. The combustion liner 46 is located inside (i.e., circumferentially surrounded by) the outer sleeve 48, forming an annulus 47 therebetween. The combustion liner 46 may contain and channel combustion gases to the turbine section 18. The combustion liner 46 defines the combustion chamber 70 in which combustion takes place. As shown in FIG. 2, the combustion liner 46 may extend between the fuel nozzle 40 and the aft frame 118. The combustion liner 46 may have a generally cylindrical liner portion and a tapered transition portion separate from the generally cylindrical liner portion, as in many conventional combustion systems. Alternatively, the combustion liner 46 may have a one-piece (or "unibody") structure in which the generally cylindrical and tapered portions are integrated with one another. Thus, all discussions of the combustion liner 46 herein encompass both conventional combustion systems having separate liners and transition pieces, and combustion systems having unibody liners. Additionally, the present disclosure is equally applicable to combustion systems in which the transition piece of the turbine section 18 and the first stage nozzle are integrated (also referred to as a "transition nozzle" or "integral exit piece").

[0033] 2 illustrates a combustor 17 having both a fuel nozzle 40 and one or more fuel injection assemblies 80 (also referred to as an axial fuel staging (AFS) system), as described further herein. The one or more fuel nozzles 40 may be located at a forward end of the combustor 17. Fuel may be routed into the fuel nozzles 40 through a fuel supply conduit 38 that extends through an end cover 42. The fuel nozzles 40 deliver the fuel and compressed air 15 to a primary combustion zone 72 where combustion occurs. In some embodiments, the fuel and compressed air 15 are mixed into a mixture before reaching the primary combustion zone 72.

[0034] The combustion liner 46 may be surrounded by an outer sleeve 48 spaced radially outward of the combustion liner 46 to define an annulus 47 through which the compressed air 15 flows to the head end of the combustor 17. For example, the compressed air 15 enters the annulus 47 through the outer sleeve 48 (e.g., through impingement holes proximate the aft frame 118) and travels toward the end cover 42, with the compressed air 15 in the annulus 47 flowing counter to the direction of the combustion gases 172 (34 in FIG. 1 ) in the combustion liner 46. Heat is convectively transferred from the combustion liner 46 to the compressed air 15, cooling the combustion liner 46 and warming the compressed air 15.

[0035] In some embodiments, the outer sleeve 48 may include a flow sleeve and an impingement sleeve coupled together. The flow sleeve may be located at the forward end and the impingement sleeve may be located at the aft end. Alternatively, the outer sleeve 48 may have a unitary (or "unisleeve") construction in which the flow sleeve and impingement sleeve are axially integrated with one another. As previously mentioned, any discussion of the outer sleeve 48 herein is intended to encompass both conventional combustion systems having separate flow sleeves and impingement sleeves and combustion systems having a unisleeve outer sleeve.

[0036] The forward casing 50 and the end cover 42 of the combustor 17 define a head end air plenum 122 that includes one or more fuel nozzles 40. The fuel nozzles 40 may be any type of fuel nozzle, such as a bundle tube fuel nozzle or a swirler nozzle (often referred to as a "swozzle"). The fuel nozzles 40 may be disposed within the head end air plenum 122 that is at least partially defined by the forward casing 50. In many embodiments, the fuel nozzles 40 may extend from the end cover 42. For example, each fuel nozzle 40 may be coupled to an aft face of the end cover 42 via a flange (not shown). As shown in FIG. 2, the one or more fuel nozzles 40 may be partially surrounded by a combustion liner 46. The aft or downstream ends of the fuel nozzles 40 pass through or collectively define a cap plate 44 that defines an upstream end of the combustion chamber 70.

[0037] The fuel nozzles 40 may be in fluid communication with a first fuel supply 150 configured to supply a first fuel 158 to the fuel nozzles 40. In many embodiments, the first fuel 158 may be a fuel mixture including natural gas (such as methane, ethane, propane, or other suitable natural gas) and / or hydrogen. In other embodiments, the first fuel 158 may be pure natural gas or pure hydrogen (e.g., 100% hydrogen, which may or may not include some amount of contaminants) such that the first fuel is not a mixture of multiple fuels. In an exemplary embodiment, the first fuel 158 and the compressed air 15 may be mixed together in the fuel nozzles 40 to form a first mixture of the compressed air 15 and the first fuel 158 before being ejected (or injected) by the fuel nozzles 40 into the primary combustion zone 72.

[0038] The forward casing 50 may be fluidly and mechanically connected to a compressor discharge casing 60, which defines a high pressure plenum 66 around the combustion liner 46 and the outer sleeve 48. Compressed air 15 from the compressor section 14 passes through the high pressure plenum 66 and enters the combustor 17 through an opening (not shown) in the downstream end of the outer sleeve 48 (indicated by the arrow near the aft frame 118). The compressed air travels upstream through the annulus 47 and reverses direction at the end cover 42 to enter the fuel nozzles 40 for head end cooling. In particular, the compressed air 15 flows from the high pressure plenum 66 through an opening defined in the outer sleeve 48 into the annulus 47 at the aft end of the combustor 17. The compressed air 15 travels upstream from the aft end of the combustor 17 to the head end air plenum 122, where the compressed air 15 reverses direction to enter the fuel nozzles 40.

[0039] In the exemplary embodiment, a fuel injection assembly 80 is provided to deliver a second fuel / air mixture downstream from the primary combustion zone 72 to the secondary combustion zone 74. For example, the second flow of fuel and air may be introduced into the secondary combustion zone 74 by one or more fuel injectors 200.

[0040] The primary combustion zone 72 and secondary combustion zone 74 may each be a portion of the combustion chamber 70 and may be defined by the combustion liner 46. For example, the primary combustion zone 72 may be defined from the exit of the fuel nozzle 40 to the fuel injectors 200, and the secondary combustion zone 74 may be defined from the fuel injectors 200 to the aft frame 118. In this arrangement, the forward-most boundary of the fuel injectors 200 may define the end of the primary combustion zone 72 and the beginning of the secondary combustion zone 74 (e.g., the axial location where the second flow of fuel and air is introduced).

[0041] Combustion systems having such axially separated combustion zones are described as "axial fuel staging" (AFS) systems. The fuel injection assemblies 80 may be circumferentially spaced apart from one another on the outer sleeve 48 (e.g., equally spaced apart in some embodiments). In many embodiments, the combustor 17 may include four fuel injection assemblies 80 spaced apart from one another and configured to inject the second mixture of fuel and air into the secondary combustion zone 74 via the fuel injectors 200. In other embodiments, the combustor 17 may include any number of fuel injection assemblies 80 (e.g., 1, 2, 3, or up to 10).

[0042] 2, each fuel injection assembly 80 may include a fuel injector 200 and a boss 300 circumferentially and axially aligned with the fuel injector 200. The fuel injector 200 may be coupled to the outer sleeve 48, and the boss 300 may be coupled to the combustion liner 46 and disposed within the annulus 47. In particular, the fuel injector 200 may be coupled to a radially outer surface of the outer sleeve 48, and the boss 300 may be coupled to a radially outer surface of the combustion liner 46. The boss 300 may be radially spaced apart from the fuel injector 200. As described in more detail below, the boss 300 may be fluidly connected to the annulus 47, and the fuel injector 200 may be fluidly connected to the high pressure plenum 66.

[0043] The fuel supply conduit 102 may be fluidly coupled to the fuel injector 200. The fuel injector 200 may be in fluid communication with a second fuel supply 152 configured to supply a second fuel 160 to the fuel injector 200 via the fuel supply conduit 102. The second fuel supply 152 may be the same as or different from the first fuel supply 150 such that the fuel injector 200 is supplied with the same or a different fuel as the fuel nozzle 40. In many embodiments, the second fuel 160 may be a fuel mixture including natural gas (such as methane, ethane, propane, or other suitable natural gas) and / or hydrogen. In other embodiments, the second fuel 160 may be pure natural gas or pure hydrogen (e.g., 100% hydrogen, which may or may not include some amount of contaminants) such that the first fuel is not a mixture of multiple fuels. In an exemplary embodiment, the second fuel 160 and the compressed air 15 may mix together in the fuel injector 200 to form a mixture of compressed air 15 and the second fuel 160 before being injected into the boss 300, which is further mixed (or diluted) with air from the annulus 47 before being injected into the secondary combustion zone 74.

[0044] 3, a close-up perspective view of a portion of the combustor 17 and fuel injection assembly 80 is shown in accordance with an embodiment of the present disclosure. As shown, the fuel injection assembly 80 may include a fuel injector 200 coupled to the outer sleeve 48. In particular, the fuel injector 200 may be coupled to a radially outer or outer surface of the outer sleeve 48. For example, the fuel injector 200 may include a body 204 and an injector flange 206 extending outwardly from the body 204. One or more fasteners 208 (such as threaded fasteners or other suitable fasteners) may extend through the injector flange 206 and into the outer sleeve 48 to couple the fuel injector 200 to the outer sleeve 48. One or more of the fasteners 208 may extend through the injector flange 206 and into a boss 300 (example boss 300 shown in FIGS. 8-10 ).

[0045] In many embodiments, the body 204 of the fuel injector 200 may extend along an axial centerline 252 between the forward endwall 210 and the aft endwall 212. In many embodiments, the axial centerline 252 of the fuel injector 200 may be generally aligned with the axial direction A of the combustor 17 (or may be at a visible angle relative to the axial direction A of the combustor 17). The sidewalls 214 may extend generally axially between the forward endwall 210 and the aft endwall 212 relative to the axial centerline 252 of the fuel injector 200. In many embodiments, the forward endwall 210 and the aft endwall 212 may each include a straight portion 216 and an angled portion 218. The straight portion 216 is oriented generally perpendicular to the axial centerline 252, and the angled portion 218 extends between the straight portion 216 and each of the sidewalls 214.

[0046] The conduit fitting 215 may extend outwardly from the forward endwall 210 of the body 204 along an axial centerline 252. In particular, the conduit fitting 215 may extend outwardly along the axial centerline 252 of a straight portion 216 of the forward endwall 210. The conduit fitting 215 may be fluidly coupled to the fuel supply conduit 102 such that the conduit fitting 215 functions to receive a flow of fuel from the fuel supply conduit 102. The conduit fitting 215 may have any suitable size and shape and may be integrally formed with or coupled to any suitable portion of the fuel injector 200 that enables the conduit fitting 215 to function as described herein.

[0047] In an exemplary embodiment, the fuel injection assembly 80 may further include a debris filter 400 coupled to the fuel injector 200. The debris filter 400 may surround the fuel injector 200 such that all air entering the fuel injector 200 from the high pressure plenum 66 passes through the debris filter 400. For example, the debris filter 400 may extend between the forward endwall 210, the aft endwall 212, and the sidewall 214. The debris filter 400 may have a number of holes 402 ( FIG. 5 ) defined therethrough to allow fluid communication between the high pressure plenum 66 and the fuel injector 200. The number of holes 402 may be sized to prevent debris (such as soot or other debris) from entering the fuel injector 200, which advantageously prevents the premixer tubes 226 and their respective fuel ports 240 from clogging. Additionally, the debris filter 400 may function as an inlet flow conditioner. That is, the debris filter 400 may function to reduce non-uniformity in the compressed air from the high pressure plenum 66 before it enters the fuel injector 200 .

[0048] Figures 4 and 5 each show different cross-sectional views of a combustor 17 including a fuel injection assembly 80 according to an embodiment of the present disclosure. Specifically, Figure 4 shows a cross-sectional view of the combustor 17 shown in Figure 3 taken along line 4-4, and Figure 5 shows a cross-sectional view of the combustor 17 shown in Figure 3 taken along line 5-5.

[0049] As shown in FIGS. 4 and 5 , the combustor 17 may include a combustion liner 46 that defines a combustion chamber 70 that includes a secondary combustion zone 74. The outer sleeve 48 may be radially spaced from the combustion liner 46 such that an annulus 47 is defined between the outer sleeve 48 and the combustion liner 46. The combustor 17, including the fuel injection assembly 80, may be disposed within a high pressure plenum 66. The annulus 47 may be fluidly connected to the high pressure plenum 66 via one or more impingement openings 90. The impingement openings 90 may be directed and sized to direct high pressure air 92 from the high pressure plenum 66 against an outer surface of the combustion liner 46. During the impingement process, the high pressure air 92 experiences a pressure drop by passing through the impingement openings 90 and becoming low pressure air 94, and undergoes energy transfer by removing heat from the combustion liner 46 (i.e., the low pressure air 94 picks up heat). Low pressure air 94 may be supplied to fuel injectors 200, as described below.

[0050] Fuel injection assembly 80 includes fuel injector 200, boss 300, debris filter 400, and insert 500 (which may be integrally formed with boss 300 in some embodiments). Fuel injector 200 may be coupled to outer sleeve 48 (e.g., via one or more fasteners 208), and fuel injector 200 may extend radially outward from outer sleeve 48 toward high pressure plenum 66. Boss 300 may be fixedly coupled to combustion liner 46 (e.g., via annular weld joint 302) and disposed within annulus 47.

[0051] In many embodiments, the boss 300 may form at least a portion of the annular wall 308. The annular wall 308 may define a mixing passage 312 extending along a central axis 350. The central axis 350 may be disposed centrally of the mixing passage 312 and may be oriented in a generally radial direction (e.g., generally parallel to the radial direction R of the combustor 17). In particular, the boss 300 may include a flange portion 304 and an annular wall portion 306. The annular wall portion 306 may be coupled to the insert 500 such that the annular wall portion 306 and the insert together form the annular wall 308.

[0052] It is noted that although the insert 500 and boss 300 are shown and described as separate pieces (which may be advantageous for testing and / or repairability by easily replacing the insert 500), the insert 500 may in other embodiments be integrally formed with the boss 300 (which may be advantageous for reducing manufacturing costs). In such embodiments, the boss 300 may include the annular wall 308 such that the mixing channel 312 is completely defined by the boss 300.

[0053] The flange portion 304 may extend generally axially and circumferentially, and the annular wall portion 306 may extend generally radially (i.e., generally perpendicularly from) the flange portion 304. The flange portion 304 may be fixedly coupled to the combustion liner 46 (e.g., via annular weld joint 302).

[0054] The flange portion 304 may partially define the combustion chamber 70. For example, the flange portion 304 may include a radially outer side 305 and a radially inner side 309. The radially inner side 309 may be aligned with the inner surface 49 of the combustion liner 46 such that the flange portion 304 partially defines the combustion chamber 70 (e.g., exhaust gases may contact the radially inner surface 309 of the flange portion 304). The flange portion 304 may extend outwardly from the annular wall portion 306 to an annular edge 310. The annular edge 310 may be a terminal end of the flange portion 304. The annular edge 310 may be welded to the combustion liner 46 (e.g., via annular weld joint 302). The annular wall portion 306 may extend generally radially to a terminal end 313.

[0055] In many embodiments, boss 300 may include an inner surface 314 having an angled portion 315 (eg, inclined, angled, or oblique with respect to radial direction R and / or central axis 350 ) and a straight portion 317 .

[0056] The insert 500 may define an outer surface 514 and an inner surface 516 (defining the mixing channel 312). The outer surface 514 may include an angled portion 518 and a straight portion 520. The angled portion 518 of the outer surface 514 of the insert 500 may be complementary (or parallel and co-extending) with the angled portion 315 of the inner surface 314 of the annular wall 306 of the boss 300. Similarly, the straight portion 520 of the outer surface 514 of the insert 500 may be complementary (or parallel and co-extending) with the straight portion 317 of the inner surface 314 of the annular wall 306 of the boss 300. As described in more detail below, the outer surface 514 of the insert 500 may be spaced apart from the inner surface 314 of the boss 300 such that a cooling gap 602 is defined between the boss 300 and the insert 500.

[0057] As shown in FIGS. 4 and 5 , the insert 500 may be annular (e.g., the insert 500 may surround the central axis 350). The insert 500 may include end walls 504 spaced axially apart from one another and a side wall 506 connecting the end walls 504. The end walls 504 may be generally perpendicular to the side walls 506, which may extend generally axially in many embodiments. The insert 500 may define a mixing passage 312, which may be generally rectangular in shape (or stadium shaped). That is, the side walls 506 may be longer than the end walls 504 such that the mixing passage 312 is elongated in the axial direction A, which advantageously allows the fuel injection assembly to introduce more fuel / air without obstructing a large portion of the annulus 47.

[0058] The insert 500 may extend radially between a base portion 508 and a tip portion 510. The base portion 508 may be generally aligned or flush (e.g., radially) with the radially inner surface 309 of the flange portion 304. The tip portion 510 may be arcuate or rounded, which may advantageously prevent fuel / air from the fuel injector 200 from creating flow vortices at the tip portion 510. Additionally, the insert 500 may define a step 512 at the radially outer end of the ramp. The step 512 may contact the terminal end 313 of the annular wall portion 306 of the boss 300 such that the insert 500 seats (i.e., contacts) the terminal end 313 of the annular wall portion 306 of the boss 300.

[0059] 4 and 5 , the fuel injector 200 may further include a radially outer wall 220 and a radially inner wall 222 that at least partially define a fuel plenum 224. The radially outer wall 220 and the radially inner wall 222 may extend between the forward endwall 210, the aft endwall 212, and the sidewall 214 of the fuel injector 200. In this manner, the fuel plenum 224 may be collectively referred to by the radially outer wall 220, the radially inner wall 222, the forward endwall 210, the aft endwall 212, and the sidewall 214. The fuel plenum 224 may receive a flow of fuel via a conduit fitting 215.

[0060] In an exemplary embodiment, fuel injector 200 may further include a plurality of premixer tubes 226 each extending radially along an injection axis 228 from an inlet end 230 on outer wall 220, through fuel plenum 224 and radially inner wall 222, to an outlet end 232. Each of premixer tubes 226 may define a premix passage 234 extending between an inlet 236 at inlet end 230 to an outlet 238 at outlet end 232. In many embodiments, injection axis 228 of each premixer tube 226 may be a centerline of premixer tube 226. In many embodiments, each premixer tube 226 of the plurality of premixer tubes 226 may include one or more fuel ports 240 that fluidly connect fuel plenum 224 to premix passage 234. For example, as shown in FIG. 4, each premix passage 234 may include two fuel ports 240 diametrically opposed to one another (e.g., a forward fuel port and an aft fuel port), which advantageously provides uniform fuel distribution within the premix passage 234.

[0061] In various embodiments, the multiple premix tubes 226 may be fluidly connected to a high pressure air source (such as the high pressure plenum 66 shown in FIG. 5 ). For example, the premix passage 234 may receive a flow of high pressure air 92 (compressed air 15 in FIG. 2 ) from the high pressure plenum 66 via the inlet 236. The mixing passage 312 may be fluidly connected to a low pressure air source (e.g., the annulus 47). The mixing passage 312 may receive a mixture of high pressure air 92 and fuel from each of the premix tubes 226. Additionally, the mixing passage 312 may receive low pressure air 94 from the annulus 47.

[0062] The boss 300 and the insert 500 may be radially spaced apart from the fuel injector 200 such that a radial gap 272 is defined between the insert 500 and the fuel injector 200. For example, the radial gap 272 may be defined between the tip 264 of the premixer tube 226 and the tip 510 of the insert 500. A multi-fluid interaction area 600 may be defined between the outlet 238 of the premixer tube 226 and the inlet of the mixing passage 312. For example, the multi-fluid interaction area 600 may receive a mixture of high pressure air 92 and fuel from each of the premixer tubes 226. In addition, the multi-fluid interaction area 600 may receive low pressure air 94 from the annulus 47, which advantageously further mixes the fuel / air within the mixing passage 312 and dilutes the fuel closer to a desired fuel / air ratio before delivering the fuel / air to the combustion chamber 70.

[0063] 5, the injection axis 228 of each premixer tube 226 may be angled toward the central axis 350 of the mixing passage 312. For example, each premixer tube 226 may be oblique to the radial direction R such that the injection axis 228 is angled relative to the generally radially-oriented central axis 350 of the mixing passage 312. In this manner, the outlet end 232 of each premixer tube 226 may be closer to the central axis 350 of the mixing passage 312 than the inlet end 230.

[0064] In an exemplary embodiment, the multiple premixer tubes 226 may be arranged in multiple rows. As shown from left to right in FIG. 5 , the multiple rows may include a first outer row 244, a first inner row 246, a second inner row 250, and a second outer row 248. The first outer row 244 may be disposed between the sidewall 214 and the first inner row 246. The first inner row 246 may be disposed between the first outer row 244 and the second inner row 250. The second inner row 250 may be disposed between the first inner row 246 and the second outer row 248. The second outer row 248 may be disposed between the second inner row 250 and the sidewall 214. The first outer row 244 and the first inner row 246 may be disposed on a first side of the central axis 350, and the second outer row 248 and the second inner row 250 may be disposed on a second side of the central axis 350. In this manner, the first outer row 244 and the first inner row 246 of premixer tubes 226 may be angled opposite the second outer row 248 and the second inner row 250 of premixer tubes 226.

[0065] Each of the premixer tubes 226 may be oriented at an angle relative to the radial direction R (and / or the central axis 350). The premixer tubes 226 disposed in the outer rows 244, 248 may be tilted, inclined or angled more relative to the central axis 350 than the premixer tubes 226 disposed in the inner rows 246, 250. For example, the premixer tubes 226 disposed in the outer rows 244, 248 may be tilted about 10% or more to about 50% or more (or between about 10% and about 40%, or between about 10% and about 30%, or between about 10% and about 20%, etc.) more than the premixer tubes 226 disposed in the inner rows 246, 250.

[0066] 5 , the fuel injector 200 may further include an angled support 254 extending from the radially inner wall 222 and coupling to one or more of the premixer tubes 226 of the plurality of premixer tubes 226. The angled support 254 may extend radially inward from the radially inner wall 222 to a peak 256. In particular, the angled support 254 may include the peak 256, a first angled surface 258 extending between the peak 256 and a first end 259, and a second angled surface 260 extending between the peak 256 and a second end 261. The peak 256 may be a radially inward-most point of the angled support 254, and the peak 256 may couple to a tip 264 of one or more of the premixer tubes 226 (e.g., the inner two premixer tubes). The first and second ends 259, 261 may be where the angled support connects (or transitions) to the radially inner wall 222. The first angled surface 258 may extend radially outward from the peak 256 to a first end 259. Similarly, the second angled surface 260 may extend radially outward from the peak 256 to a second end 261. The peak 256 of the angled support 254 may be aligned along the central axis 350, along the axial centerline 252 of the fuel injector 200 (FIG. 7).

[0067] The angled supports 254 may advantageously provide increased structural integrity to the outer portion 260 of the premixer tube 226 and the entire fuel injector 200. Additionally, the angled supports 254 may advantageously facilitate additive manufacturing of the fuel injector 200 by preventing excessive overhang during additive manufacturing.

[0068] FIG. 6 illustrates a cross-sectional perspective view of a portion of a combustor 17 including a fuel injection assembly 80 according to an embodiment of the present disclosure. FIG. 7 illustrates a plan view of the fuel injector 200 shown in FIG. 6 along line 7-7. In particular, FIG. 7 illustrates a schematic axial-transverse plan view of the fuel injector 200, where the transverse direction T is tangent to the circumferential direction C and perpendicular to the central axis 350. As illustrated in FIGS. 6 and 7, which will be described in more detail below, adjacent rows of the premixer tubes 226 may be staggered side-by-side (e.g., axially staggered or offset relative to the axial centerline 252). As illustrated in FIG. 7, the angled support 254 (including the peak 256, the first angled surface 258, and the second angled surface 260) may extend along the axial centerline 252 from the forward endwall 210 to the aft endwall 212 of the fuel injector 200.

[0069] The premixer tubes 226 disposed in the first outer row 244 may be referred to as first outer premixer tube(s) 226A. The premixer tubes 226 disposed in the first inner row 246 may be referred to as first inner premixer tubes 226B. The premixer tubes 226 disposed in the second inner row 250 may be referred to as second inner premixer tubes 226C. The premixer tubes 226 disposed in the second outer row 248 may be referred to as second outer premixer tube(s) 226D.

[0070] Each premixer tube 226A-D may extend radially inward from the radially inner wall 222 toward the boss 300 and the insert 500. For example, as shown in FIG. 5, each premixer tube 226A-D may include an inner portion 257 and an outer portion 263. The inner portion 257 may be contained within (i.e., may be contained within) the fuel plenum 224 and may extend between the radially outer wall 220 and the radially inner wall 222. The outer portion 263 may extend radially inward from the radially inner wall 222 toward the boss 300 and the insert 500 (i.e., may be outside of the fuel plenum 224). For example, the outer portion 260 of each premixer tube 226A-D may extend from a base 262 to a tip 264 of the radially inner wall 222 (e.g., a radially inner end of each premixer tube).

[0071] As shown in FIG. 7, each premixer tube 226 in the rows 244, 246, 250, 248 of premixer tubes 226A-D may be aligned with the other premixer tubes 226A-D in the respective rows 244, 246, 250, 248 along a respective row axis 270A-D. Each of the row axes 270A-D may be substantially parallel to the axial centerline 252 of the fuel injector 200 and / or parallel to the axial direction A of the combustor 17. Each row axis 270A-D may extend through a center point of each of the premixer tubes 226A-D aligned along the respective row axis 270A-D. In many embodiments, each of the first outer premixer tubes 226A may be aligned along the row axis 270A. Each of the first inner premixer tubes 226B may be aligned along the row axis 270B. Each of the second inner premixer tubes 226C may be aligned along a row axis 270C. Each of the second outer premixer tubes 226D may be aligned along a row axis 270D.

[0072] In an exemplary embodiment, each row 244, 246, 248, 250 of premixer tubes 226A-D may be offset relative to an adjacent row of premixer tubes 226A-D such that the rows are staggered. For example, each row 244, 246, 248, 250 of premixer tubes 226A-D may be axially offset relative to an adjacent row of premixer tubes 226A-D in the axial direction A. For example, the premixer tubes 226 disposed in the first outer row 244 and the second inner row 250 may be axially aligned with one another and axially offset from the premixer tubes 226 disposed in the second outer row 248 and the first inner row 246. Similarly, the premixer tubes 226 disposed in the first inner row 246 and the second outer row 248 may be axially aligned with one another and axially offset from the premixer tubes 226 disposed in the first outer row 244 and the second inner row 250. This advantageously allows more premixer tubes 226 to be utilized in the fuel injector 200 when compared to a fuel injector having a non-staggered arrangement.

[0073] In various embodiments, one or more of the premixer tubes 226 of the plurality of premixer tubes 226 may define a non-circular opening in the axial-transverse plane. For example, the non-circular opening may include a stadium (e.g., a rectangle with rounded ends), a diamond, a rectangle, a triangle, an ellipse, or other non-circular shape. In an exemplary embodiment, as shown in FIG. 7, one or more of the premixer tubes 226 of the plurality of premixer tubes 226 may define an elliptical opening 266 in the axial-transverse plane. The elliptical opening 266 may include a major axis 268 and a minor axis 269 that are orthogonal to one another. The minor axis 269 may be generally parallel to the axial direction A of the combustor 17 and / or the axial centerline 252 of the fuel injector 200. The major axis 268 may be longer than the minor axis 269 and may be perpendicular to the axial direction A of the combustor and / or the axial centerline 252 of the fuel injector 200. The elliptical openings 266 may advantageously allow for better filling (e.g., of the premixer tubes 226), flow interaction, mixing, and reduced flame holding tendency when compared to other shapes (such as circular).

[0074] 8 and 9, two different views of the boss 300 of the fuel injection assembly 80 are illustrated in accordance with an exemplary aspect of the present disclosure. In particular, FIG. 8 illustrates a perspective view of the boss 300, and FIG. 9 illustrates a top-down plan view of the boss 300 in accordance with an embodiment of the present disclosure. As described above, the boss 300 may include a flange portion 304 and an annular wall portion 306. The annular wall portion 306 may be coupled to the insert 500 such that the annular wall portion 306 and the insert 500 together form an annular wall 308 (FIG. 5). The boss 300 may extend generally radially along a central axis 350. The central axis 350 may be aligned with a radial direction R when the boss 300 is installed in the combustor 17. Additionally, the boss 300 may include an axial centerline 352 perpendicular to the central axis 350. The axial centerline 352 may be generally parallel to an axial direction A of the combustor 17 when the boss 300 is installed in the combustor 17. However, in some embodiments, the axial centerline 352 of the boss 300 may be inclined or angled relative to the axial direction A of the combustor 17 .

[0075] 8 and 9, the flange portion 304 may extend generally axially and circumferentially, and the annular wall portion 306 may extend generally radially (i.e., generally perpendicularly from) the flange portion 304. The flange portion 304 may be fixedly coupled (e.g., via an annular weld joint 302) to the combustion liner 46 (FIGS. 4 and 5). The flange portion 304 may extend outwardly from the annular wall portion 306 to an annular edge 310. The annular edge 310 may be a terminal end of the flange portion 304. The annular edge 310 may be welded (e.g., via annular weld joint 302) to the combustion liner 46.

[0076] The annular wall portion 306 may extend generally radially from a root portion 311 at an intersection with the flange portion 304 to a terminal end portion 313. In many embodiments, as shown in Figures 8 and 9, the annular wall portion 306 may include a first end segment 316, a second end segment 318 spaced from the first end segment 316, and a side segment 320 extending between the first end segment 316 and the second end segment 318. The side segment 320 may extend generally axially between the first end segment 316 and the second end segment 318 relative to an axial centerline 352. The first end segment 316 and the second end segment 318 may be generally arcuate, rounded or otherwise curved and extend between the side segments 320. 8 and 9, the boss 300 may further include a first closure flange 322 extending from the first end segment 316 and a second closure flange 324 extending from the second end segment 318. The first closure flange 322 and the second closure flange 324 may extend away from the inner surface 314 and the opening 301 of the boss 300, respectively.

[0077] For example, the first closure flange 322 may extend in a direction generally perpendicular to the side segment 320 from the first end segment 316. Similarly, the second closure flange 324 may extend generally perpendicular to the side segment 320 from the second end segment 318. Unless otherwise stated, the first closure flange 322 and the second closure flange 324 may extend in a transverse direction T beyond the side segment 320 and extend in an axial direction A beyond their respective end segments 316, 318. As discussed above, the transverse direction T may be tangent to the circumferential direction C and perpendicular to the central axis 350.

[0078] The first closure flange 322 and the second closure flange 324 may each include a first overhang portion 326, a central body portion 328, and a second overhang portion 330. The body portion 328 of the first closure flange 322 may be coupled to the first end segment 316, and the body portion 328 of the second closure flange 324 may be coupled to the second end segment 318. The central body portion 328 may extend axially outward from the respective end segments 316, 318 to which they are attached. The first overhang portion 326 may extend transversely (i.e., transversely) from a first side of the central portion 328 of the body portion 328, and the second overhang portion 330 may extend transversely from a second side of the body portion 328 opposite the first side. The first overhang portion 326 may be longer in the transverse direction T than the second overhang portion 330. The first overhang portion 326 may extend transversely from the body center portion 328 beyond the side segments 320 and the annular edge 310 of the flange portion 304. The second overhang portion 330 may extend transversely from the body center portion 328 beyond the side segments 320. In an exemplary embodiment, the first overhang portion 326 may define a hole 332 through which a fastener (e.g., a threaded fastener) may extend to couple the boss 300 to one or more components of the fuel injection assembly 80 (e.g., the insert 500, the fuel injector 200 and / or the debris filter 400) and / or one or more components of the combustor 17 (e.g., the combustion liner 46 and / or the outer sleeve 48).

[0079] During operation, the closure flanges 322, 324 may advantageously prevent air from the annulus 47 from flowing into the mixing passage 312 through the end segments 316, 318 of the annular wall 306. For example, it may be advantageous for all of the air from the annulus 47 to enter the mixing passage 312 circumferentially (e.g., on the side segments 320) rather than axially to increase fuel / air mixing and prevent flow separation and / or flame holding problems.

[0080] In many embodiments, the boss 300 may include an inner surface 314 that defines an opening 301. The opening 301 may generally be shaped as a geometric stadium (e.g., a rectangle with two circular ends). With brief reference to FIGS. 4 and 5, an insert 500 may be disposed within the opening 301, and the insert 500 may define a mixing passage 312 (which may also be shaped as a geometric stadium). The insert 500 may be directly exposed to the hot fuel / air in the mixing passage 312, and since the flange portion 304 of the boss 300 partially defines the combustion chamber 70, the boss 300 may be exposed to the combustion gases in the combustion chamber 70. As such, it is important that both the insert 500 and the boss 300 are robust to high temperatures. The boss 300 shown and described herein advantageously includes a plurality of serpentine cooling passages 340 which function to cool both the boss 300 and the insert 500, thereby increasing the hardware life of these components and increasing the overall efficiency of the combustor 17.

[0081] 10 illustrates a perspective view of a boss 300 of a fuel injection assembly 80 according to an embodiment of the present disclosure. As shown, the boss 300 may define a serpentine or serpentine cooling passage 334 (shown in phantom) extending from an inlet 336 on the flange portion 304 to an outlet 338 on the inner surface 314. In particular, the boss 300 may define a plurality of serpentine cooling passages 334 extending from respective inlets 336 on the flange portion 304 to respective outlets 338 on the inner surface 314. The inlets 336 of each serpentine cooling passage 334 may be located on the flange portion 304 closer to the annular wall 306 than the annular edge 310. In particular, the inlets 336 of each serpentine cooling passage 334 may be defined on the radially outer surface 305 proximate the annular wall 306 (i.e., closer to the annular wall 306 than the annular edge 310). The multiple serpentine cooling passages 334 may be spaced apart from one another. For example, the multiple serpentine cooling passages 334 may be spaced (e.g., equally spaced) around the periphery of the opening 301 to provide cooling over a larger area of ​​the flange portion 304.

[0082] 11 and 12 respectively show close-up cross-sectional views of a combustor 17 having a boss 300 coupled to a combustion liner 46 and a serpentine cooling passage 334 according to an embodiment of the present disclosure. As mentioned above, the flange portion 304 of the boss 300 may extend to an annular edge 310, which may be fixedly coupled (e.g., via an annular weld joint 302) to the combustion liner 46. The boss 300 may include an inner surface 314 spaced apart from the insert 500 such that a cooling gap 602 is defined between the boss 300 and the insert 500. In particular, the cooling gap 602 may be defined between a sidewall 506 of the insert and the inner surface 314 of the boss 300. Referring briefly to FIG. 5, as shown, the cooling gap 602 extends radially outward from the outlet 338 toward the terminal end 313 of the boss 300. Additionally, the cooling gap 602 may extend radially inward from the outlet 338 to a film cooling outlet 604. The film cooling outlet 604 may supply film cooling air to the base 508 of the insert 500 during operation of the fuel injection assembly 80 before extending along the radially inner surface 309 of the flange portion 304.

[0083] In the exemplary embodiment, the serpentine cooling passage 334 may extend from an inlet 336 in fluid communication with a source of low pressure air (such as the annulus 47) to an outlet 338 in fluid communication with the cooling gap 602. The inlet 336 may be disposed on the flange portion 304 of the boss 300, and the outlet 338 may be disposed on the inner surface 314 opposite the sidewall 506. In the exemplary embodiment, the outlet 338 of the serpentine cooling passage 334 may direct the air to impinge on the insert 500 (e.g., air exiting the outlet 338 may travel across the cooling gap 602 and strike the insert 500). The air within the cooling gap 602 may then exit through the film cooling outlet 604.

[0084] In many embodiments, the serpentine cooling passage 334 may include an inlet portion 342, a U-shaped portion 344, and an outlet portion 346. The inlet portion 342 may extend from the inlet 336 toward the annular edge 310 (with the weld joint 302), and the outlet portion 346 may extend from the annular edge 310 to the outlet 338. In particular, the inlet portion 342 may extend from the inlet 336 to the U-shaped portion 344, and the outlet portion 346 may extend from the U-shaped portion 344 to the outlet 338. The U-shaped portion 344 may fluidly couple the inlet portion 342 with the outlet portion 346. For example, the U-shaped portion 344 may extend from the inlet portion 342 toward the annular edge 310 to an apex 348. Further, the U-shaped portion 344 may extend from the apex 348 away from the annular edge 310 to the outlet portion 346.

[0085] In some embodiments, the inlet portion 342 may be generally parallel to the outlet portion 346, as shown in FIG. 11. In other embodiments, the inlet portion 342 and the outlet portion 346 may be angled, inclined, or tilted relative to one another. For example, as shown in FIG. 12, the inlet portion 342 may diverge away from the outlet portion 346 as the inlet portion 342 extends from the inlet 336 toward the annular edge 310. In addition, the outlet portion 346 may converge toward the inlet portion 342 as the outlet portion 346 extends away from the annular edge 310 toward the outlet 338. In some embodiments, the plurality of serpentine cooling passages 334 may include serpentine cooling passages 334 having parallel inlet and outlet portions 342 and 346 (as in FIG. 11) along the sides of the boss 300 and serpentine cooling passages 334 having non-parallel inlet and outlet portions 342 and 346 (as in FIG. 12) along the ends of the boss 300.

[0086] In various embodiments, at least one of the inlets 336 and / or outlets 338 of the serpentine cooling passages 334 may have a non-circular shape, which may advantageously enhance the cooling effect of the serpentine cooling passages 334 as well as facilitate additive manufacturing of the boss 300. In an exemplary embodiment, the inlets 336 and the outlets 338 may each have a different non-circular shape. For example, the inlets 336 may have a first non-circular shape (e.g., teardrop shape) and the outlets 338 may have a second non-circular shape (e.g., hexagonal) that is different from the first non-circular shape. As shown in FIGS. 11 and 12, in an exemplary embodiment, the inlets 336 may have a teardrop shape 354. However, in other embodiments (not shown), the inlets 336 may have a polygonal shape or other suitable shape, which may or may not be symmetrical. Referring now to FIG. 13, a close-up plan view of the boss 300 shown in FIG. 12 taken along line 13-13 is shown in accordance with an embodiment of the present disclosure. As shown, the outlet 338 may have a polygonal shape 355. That is, the outlet 338 may have a hexagonal shape with two parallel sides 356 longer than all other sides. The two parallel sides 356 may be perpendicular to the radial direction R in many embodiments.

[0087] In many embodiments, the boss 300, the fuel injector 200, the insert 500, and / or the debris filter 400 described herein may each be integrally formed as a single piece. That is, the boss 300, the fuel injector 200, the insert 500, and / or the debris filter 400 may each be manufactured as a single body or object without internal welded joints, internal brazed joints, internal adhesive joints, or combinations thereof. In an exemplary implementation, this may be done by utilizing additive manufacturing systems and methods, such as direct metal laser sintering (DMLS), direct metal laser melting (DMLM), or other suitable additive manufacturing techniques. In other embodiments, other manufacturing techniques, such as casting or other suitable techniques, may be used. In some examples, the boss 300 and the insert 500 may be configured as a single body or object.

[0088] Additionally, by utilizing additive manufacturing techniques, the boss 300, fuel injector 200, insert 500, and / or debris filter 400 may each be integrally formed as a single piece of continuous metal and may include fewer subcomponents and / or joints as compared to previous designs. The integral formation of each of the boss 300, fuel injector 200, insert 500, and / or debris filter 400 by additive manufacturing may be advantageous to improve the overall assembly process. For example, integral formation reduces the number of separate parts that need to be assembled, thereby reducing the associated time and overall assembly costs. Additionally, existing issues with, for example, leakage, joint quality between separate parts, and overall performance may be advantageously reduced.

[0089] The present specification has been described by way of examples to disclose the invention, including the best mode thereof, and to enable those skilled in the art to practice the invention, including making and using the apparatus or system and practicing the method. The patentable scope of the invention is defined by the claims, and may include other examples that are obvious to those skilled in the art. Such other examples are within the scope of the claims if they have elements that are not literally different from the claims, or have equivalent elements that are only insubstantial different from the claims.

[0090] Further aspects of the present invention are set out in the following embodiment section. [Embodiment 1] 1. A fuel injection assembly for a combustor of a gas turbine, the fuel injection assembly comprising: a fuel injector configured to couple to an outer sleeve of the combustor; and a boss spaced from the fuel injector and configured to couple to a combustion liner of the combustor, the boss comprising a flange portion, an annular wall portion extending from the flange portion, and an inner surface, the boss defining a serpentine cooling passage extending from an inlet in the flange portion to an outlet on the inner surface. [Embodiment 2] The fuel injection assembly of embodiment 1, further comprising an insert coupled to the boss, the insert defining a cooling gap between the boss and the insert. [Embodiment 3] The fuel injection assembly of embodiment 1 or embodiment 2, wherein an inlet of the serpentine cooling passage is in fluid communication with the source of low pressure air and an outlet of the serpentine cooling passage is in fluid communication with the cooling gap. [Embodiment 4] The fuel injection assembly of any one of embodiments 1 to 3, wherein the flange portion of the boss extends to the annular edge. [Embodiment 5] A fuel injection assembly as described in any one of embodiment paragraphs 1 to 4, wherein the serpentine passage includes an inlet section, an outlet section, and a U-shaped section fluidly connecting the inlet section and the outlet section, the inlet section extending from the inlet toward the annular edge, and the outlet section extending from the annular edge toward the outlet. [Embodiment 6] The fuel injection assembly of any one of embodiments 1 to 5, wherein the inlet portion is generally parallel to the outlet portion. [Embodiment 7] The fuel injection assembly of any one of embodiment paragraphs 1 through 6, wherein the inlet portion diverges away from the outlet portion as it extends from the inlet towards the annular edge, and the outlet portion converges towards the inlet portion as the outlet portion extends away from the annular edge towards the outlet. [Embodiment 8] A fuel injection assembly as described in any one of embodiment paragraphs 1 to 7, wherein the flange portion of the boss includes a radially outer surface and an inlet of the serpentine cooling passage is defined in the radially outer surface adjacent the annular wall portion. [Embodiment Item 9] The fuel injection assembly of any one of embodiment paragraphs 1 through 8, wherein at least one of the inlet or outlet of the serpentine cooling passage is non-circular. [Embodiment 10] The fuel injection assembly of any one of embodiment paragraphs 1 to 9, wherein the serpentine cooling passage is a first serpentine cooling passage of a plurality of serpentine cooling passages defined in the boss, the plurality of serpentine cooling passages being spaced apart from one another. [Embodiment 11] The fuel injection assembly of any one of embodiments 1 to 10, wherein the annular wall includes a first end segment, a second end segment, and a side segment extending between the first end segment and the second end segment, and the boss includes a first closure flange extending from the first end segment and a second closure flange extending from the second end segment. [Embodiment 12] 1. A combustor comprising: one or more fuel nozzles; a combustion liner extending downstream from the fuel nozzles; an outer sleeve spaced from and surrounding the combustion liner to define an annulus between the combustion liner and the outer sleeve; and a fuel injection assembly disposed downstream from the one or more fuel nozzles, the fuel injection assembly comprising a boss spaced from the fuel injector and coupled to the combustion liner of the combustor, the boss having a flange portion, an annular wall portion extending from the flange portion, and an inner surface, the boss defining a serpentine cooling passage extending from an inlet in the flange portion to an outlet on the inner surface. [Embodiment 13] 13. The combustor of embodiment 12, further comprising an insert coupled to the boss, the insert defining a cooling gap between the boss. [Embodiment 14] The combustor of embodiment paragraph 12 or embodiment paragraph 13, wherein an inlet of the serpentine cooling passage is in fluid communication with the source of low pressure air and an outlet of the serpentine cooling passage is in fluid communication with the cooling gap. [Embodiment Item 15] The combustor of any one of embodiments 12 through 14, wherein the flange portion of the boss extends to the annular edge. [Embodiment 16] The combustor of any one of embodiment paragraphs 12 through 15, wherein the serpentine passage includes an inlet section, an outlet section, and a U-shaped section fluidly connecting the inlet section and the outlet section, the inlet section extending from the inlet toward the annular edge, and the outlet section extending from the annular edge toward the outlet. [Embodiment 17] 17. The combustor of any one of embodiments 1 through 16, wherein the serpentine cooling passage is a first serpentine cooling passage of a plurality of serpentine cooling passages defined in the boss, the plurality of serpentine cooling passages being spaced apart from one another, an inlet portion of the first serpentine cooling passage being generally parallel to an outlet portion of the first serpentine cooling passage, the plurality of serpentine cooling passages including a second serpentine cooling passage having a second inlet portion and a second outlet portion, the second inlet portion diverging away from the second outlet portion as the second inlet portion extends towards the annular edge, and the second outlet portion converging towards the second inlet portion as the second outlet portion extends away from the annular edge. [Embodiment 18] The combustor of any one of embodiments 12 through 16, wherein the annular wall includes a first end segment, a second end segment, and a side segment extending between the first end segment and the second end segment, and the boss includes a first closure flange extending from the first end segment and a second closure flange extending from the second end segment. [Embodiment 19] 1. A fuel injection assembly for a combustor of a gas turbine, the fuel injection assembly comprising: a fuel injector configured to couple to an outer sleeve of the combustor; and a boss spaced from the fuel injector and configured to couple to a combustion liner of the combustor, the boss comprising a flange portion and an annular wall portion extending from the flange portion, the annular wall portion including a first end segment, a second end segment, and a side segment extending between the first end segment and the second end segment, the boss comprising a first closure flange extending from the first end segment and a second closure flange extending from the second end segment. [Embodiment 20] 20. The fuel injection assembly of claim 19, wherein the flange portion of the boss includes a plurality of serpentine cooling passages, each serpentine cooling passage having an inlet disposed adjacent the annular wall and an outlet defined in an inner surface of the annular wall, the inlet being fluidly connected with the inlet portion, the outlet being fluidly connected with the outlet portion, and the inlet and outlet portions being fluidly connected by a U-shaped portion. A fuel injection assembly for a combustor of a gas turbine, the fuel injection assembly comprising: a boss forming at least a portion of an annular wall, the annular wall defining a mixing passage extending along a central axis; and a fuel injector having radially outer and inner walls at least partially defining a fuel plenum, and a plurality of premixer tubes each extending along an injection axis from an inlet end on the radially outer wall through the fuel plenum to an outlet end, the injection axis being angled toward a central axis of the mixing passage. [Embodiment 21] The fuel injection assembly of embodiment paragraph 19 or embodiment paragraph 20, wherein at least one premixer tube of the plurality of premixer tubes defines a non-circular opening. [Embodiment 22] The fuel injection assembly of any one of embodiment paragraphs 19 through 21, wherein at least one premixer tube of the plurality of premixer tubes defines an elliptical opening. [Embodiment 23] The fuel injection assembly of any one of embodiments 19 through 22, wherein the plurality of premixer tubes are in fluid communication with a source of high pressure air and the mixing passage is in fluid communication with a source of low pressure air. [Embodiment 24] The fuel injection assembly of any one of embodiments 19 through 23, wherein the plurality of premixer tubes are arranged in a plurality of rows. [Embodiment 25] The fuel injection assembly of any one of embodiments 19 through 24, wherein the plurality of rows includes a first outer row, a first inner row, a second inner row, and a second outer row. [Embodiment 26] The fuel injection assembly of any one of embodiment paragraphs 19 through 25, wherein an inclined support extends from the radially inner wall, the inclined support being coupled to one or more premixer tubes of the plurality of premixer tubes. [Embodiment 27] The fuel injection assembly of any one of embodiments 19 through 26, wherein each row of premixer tubes is axially offset relative to an adjacent row of premixer tubes. [Embodiment 28] The fuel injection assembly of any one of embodiments 19 to 27, wherein the boss has a flange portion and an annular wall portion extending from the flange portion, the flange portion configured to couple to a combustion liner of the combustor. [Embodiment 29] The fuel injection assembly of any one of embodiments 19 through 28, further comprising an insert coupled to the annular wall of the boss, the insert and the annular wall together forming the annular wall. [Embodiment 30] The fuel injection assembly of any one of embodiments 19 through 29, further comprising a debris filter coupled to the fuel injector. [Embodiment 31] 1. A combustor comprising: one or more fuel nozzles; a combustion liner extending downstream from the fuel nozzles; an outer sleeve spaced from and surrounding the combustion liner to define an annulus between the combustion liner and the outer sleeve; and a fuel injection assembly disposed downstream from the one or more fuel nozzles, the fuel injection assembly comprising: a boss coupled to the combustion liner, the boss forming at least a portion of an annular wall, the annular wall defining a mixing passage extending along a central axis; and a fuel injector coupled to the outer sleeve radially outward from the boss, the fuel injector having radially outer and inner walls that at least partially define a fuel plenum, and a plurality of premixer tubes each extending along an injection axis from an inlet end on the radially outer wall through the fuel plenum and the radially inner wall to an outlet end, the injection axis being inclined toward a central axis of the mixing passage. [Embodiment 32] 32. The combustor of embodiment 31, wherein at least one premixer tube of the plurality of premixer tubes defines a non-circular opening. [Embodiment 33] The combustor of embodiment paragraph 31 or embodiment paragraph 32, wherein at least one premixer tube of the plurality of premixer tubes defines an elliptical opening. [Embodiment 34] The combustor of any one of embodiment paragraphs 31 to 33, wherein the plurality of premixer tubes are fluidly connected to a high pressure air source, the mixing passage is fluidly connected to a low pressure air source, the low pressure air source being an annulus between the combustion liner and the outer sleeve. [Embodiment 35] The combustor of any one of embodiments 31 through 34, wherein the plurality of premixer tubes are arranged in a plurality of rows. [Embodiment 36] The combustor of any one of embodiments 31 through 35, wherein the plurality of rows includes a first outer row, a first inner row, a second inner row, and a second outer row. [Embodiment 37] The combustor of any one of embodiments 31 through 36, wherein an inclined support extends from the radially inner wall, the inclined support coupled to one or more premixer tubes of the plurality of premixer tubes. [Embodiment 38] The combustor of any one of embodiments 31 through 37, wherein each row of premixer tubes is axially offset relative to an adjacent row of premixer tubes. [Embodiment 39] The combustor of any one of embodiments 31 through 38, wherein the boss comprises a flange portion and an annular wall portion extending from the flange portion, the flange portion being coupled to a combustion liner of the combustor. [Explanation of symbols]

[0091] 10. Gas Turbine Engine 17 Combustor 40 Fuel Nozzle 46 Combustion Liner 47 Annulus 48 Outer Sleeve 66 High Pressure Plenum 80 Fuel Injection Assembly 200 fuel injector 220 Radial outer wall 222 Radial inner wall 224 Fuel Plenum 226 Premixing tube 228 Injection shaft 230 Inlet end 232 Outlet end 254 Inclined support 300 Boss 304 Flange part 306 Annular wall 308 Circular Wall 312 Mixing channel 350 Central axis of mixing channel

Claims

1. A fuel injection assembly (80) for a combustor (17) of a gas turbine engine (10), the fuel injection assembly (80) comprising: a boss (300) forming at least a portion of an annular wall (308), the annular wall (308) defining a mixing channel (312) extending along a central axis (350); a fuel injector (200) having a radially outer wall (220) and a radially inner wall (222) at least partially defining a fuel plenum (224), and a plurality of premixer tubes (226) each extending along an injection axis (228) from an inlet end (230) on the radially outer wall (220), through the fuel plenum (224) to an outlet end (232); and wherein the injection axis (228) is inclined toward a central axis (350) of the mixing channel (312).

2. The fuel injection assembly (80) of claim 1, wherein at least one premixer tube (226) of the plurality of premixer tubes (226) defines a non-circular opening.

3. The fuel injection assembly (80) of claim 1, wherein at least one premixer tube (226) of the plurality of premixer tubes (226) defines an elliptical opening.

4. The fuel injection assembly (80) of claim 1 or claim 2, wherein the plurality of premixer tubes (226) are in fluid communication with the high pressure air source (66) and the mixing passage (312) is in fluid communication with the low pressure air source (47).

5. The fuel injection assembly (80) of claim 1, claim 2 or claim 4, wherein the plurality of premixer tubes (226) are arranged in a plurality of rows (244, 246, 248, 250).

6. The fuel injection assembly (80) of claim 5, wherein the plurality of rows comprises a first outer row (244), a first inner row (246), a second inner row (250), and a second outer row (248).

7. 2. The fuel injection assembly of claim 1, wherein an inclined support extends from the radially inner wall, the inclined support being coupled to at least one premixer tube of the plurality of premixer tubes.

8. The fuel injection assembly (80) of claim 5, wherein each row (244, 246, 248, 250) of premixer tubes (226) is axially offset relative to an adjacent row (244, 246, 248, 250) of premixer tubes (226).

9. 2. The fuel injection assembly of claim 1, wherein the boss comprises a flange portion and an annular wall portion extending from the flange portion, the flange portion configured to couple to a combustion liner of the combustor.

10. 10. The fuel injection assembly (80) of claim 9, further comprising an insert coupled to the annular wall portion (306) of the boss (300), the insert and the annular wall portion (306) together forming an annular wall (308).

11. The fuel injection assembly (80) of claim 1, further comprising a debris filter (400) coupled to the fuel injector (200).

12. A combustor (17), one or more fuel nozzles (40); a combustion liner (46) extending downstream from the one or more fuel nozzles (40); an outer sleeve (48) spaced apart from and surrounding the combustion liner (46) to define an annulus (47) therebetween; A fuel injection assembly (80) disposed downstream of one or more fuel nozzles (40), comprising: a fuel injection assembly (80) according to any one of claims 1 to 11; A combustor (17).

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