Fuel injection assembly having partial direct injector

Abstract

To provide a fuel injection assembly capable of supplying an alternative fuel such as hydrogen and air to a secondary combustion zone.SOLUTION: A fuel injection assembly (80) for a combustor (17) of a gas turbine engine (10) includes a fuel injector (200) formed to be coupled to an outer sleeve (48) of the combustor. A boss (300) is configured to be coupled to a combustion liner (46) of the combustor (17) at a position aligned with the fuel injector (200) in axial and circumferential directions. An insert (600) is removably coupled to the boss (300). The insert (600) includes: a flange part (304); and an annular wall part (306) extending from the flange part to define a mixing passage (312). The insert (600) defines a plurality of partial direct injector (500) arranged around the mixing passage (312) while being spaced apart from each other. The combustor (17) including the fuel injection assembly (80) is also provided.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure generally relates 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 Art

[0002] Turbo machines are utilized in various industries and applications for energy transfer. For example, a gas turbine engine generally includes a compressor section, a combustion section, a turbine section, and an exhaust section. The compressor section gradually increases the pressure of the working fluid entering the gas turbine engine and supplies the compressed working fluid to the combustion section. The compressed working fluid and fuel (such as natural gas) are mixed in the combustion section and burned in the combustion chamber to generate high-pressure and 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 a generator or the like. The combustion gases are then discharged from the gas turbine engine through the exhaust section.

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

[0004] Conventional gas turbine engines include 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 generated and discharged from the exhaust section. Regulatory requirements regarding low-emission gases from gas turbines are becoming increasingly stringent, and environmental authorities worldwide are demanding further reduction of the emission rates of NOx and other pollutants from both new and existing gas turbines.

[0005] When a mixture of natural gas and a large amount of hydrogen and / or pure hydrogen is combusted in a combustor instead of natural gas, the emission of CO2 is significantly reduced or eliminated. However, since the combustion characteristics of hydrogen are different from those of natural gas, in a conventional combustion system including a conventional AFS fuel injector, high-concentration hydrogen and / or pure hydrogen cannot be combusted without problems. For example, when high-concentration hydrogen and / or pure hydrogen is combusted in a conventional combustion system, a flashback or flame holding state in which the combustion flame moves toward the fuel supplied from the injector is promoted, which may cause serious damage to the injector in a relatively short time.

[0006] Therefore, in the art, a fuel injection assembly that can send alternative fuels (such as hydrogen) and air to a secondary combustion zone without causing flame holding or flashback problems is desired. SUMMARY OF THE INVENTION

[0007] Aspects and advantages of the fuel injection assembly and method according to the present disclosure are described in the following detailed description, and some may be apparent from the following detailed description or may be learned through the practice of the technology.

[0008] In one embodiment, a fuel injection assembly for a combustor of a gas turbine includes a fuel injector configured to couple to an outer sleeve of the combustor. A boss is configured to couple to a combustion liner of the combustor at a position axially and circumferentially aligned with the fuel injector. An insert is removably coupled to the boss. The insert includes a flange portion and an annular wall portion extending from the flange portion to define a mixing flow path. The insert defines a plurality of partial direct injectors spaced apart from each other and disposed around the mixing flow path.

[0009] In another embodiment, a combustor for a gas turbine engine is provided. The combustor includes one or more fuel nozzles, a combustion liner extending downstream of the fuel nozzles, an outer sleeve spaced from and surrounding the combustion liner to define an annulus therebetween, and a fuel injection assembly disposed downstream of the one or more fuel nozzles. The fuel injection assembly includes a fuel injector configured to couple to an outer sleeve of the combustor. A boss is configured to couple to a combustion liner of the combustor at a position axially and circumferentially aligned with the fuel injector. An insert is removably coupled to the boss. The insert includes a flange portion and an annular wall portion extending from the flange portion to define a mixing flow path. The insert defines a plurality of partial direct injectors spaced apart from each other and disposed around the mixing flow path.

[0010] The above and other features, aspects, and advantages of the present fuel injection assembly and method may be better understood by reference to the following detailed description and the claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various embodiments of the present disclosure and, together with the detailed description, serve to explain the principles of the technology.

Brief Description of the Drawings

[0011] The present fuel injection assembly and method are disclosed in sufficient detail in the following detailed description with reference to the accompanying drawings so that those skilled in the art can implement them, including the best mode of manufacturing and using the present system and method.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0012] Various embodiments of the present fuel injection assembly and method are described in detail, and one or more examples thereof are shown in the drawings. Each example is not intended to limit the technology but is for illustration purposes. In fact, it will be apparent to those skilled in the art that various modifications and changes can be made to the technology without departing from the technical scope and technical idea described in the claims. For example, features exemplified or described as part of one embodiment can be used in combination with another embodiment to form yet another embodiment. Accordingly, the present disclosure encompasses modifications and changes that fall within the scope of the appended claims and their equivalents.

[0013] The term "exemplary" as used herein means "serving as an example, instance, or illustration." Embodiments described as "exemplary" in this specification should not necessarily be construed as being more preferred or advantageous than other embodiments. Furthermore, unless otherwise specified, all embodiments described in this specification are to be construed as exemplary.

[0014] In the detailed description of the invention, reference numerals and letters are used to refer to the features shown in the drawings. In the drawings and the detailed description of the invention, like or similar reference numerals indicate like or similar members of the invention. As used herein, the terms "first", "second", and "third" are used interchangeably to distinguish one component from another and do not mean the position or importance of individual components.

[0015] The term "fluid" may be either a gas or a liquid. The term "fluid communication" means that fluid can flow or be conveyed between given regions.

[0016] As used herein, the terms "upstream" (or "front") and "downstream" (or "rear") indicate relative directions with respect to the flow of fluid in a fluid path. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction in which the fluid flows. The term "radial direction" refers to a relative direction that is substantially perpendicular to the axial centerline of a component, the term "axial direction" refers to a relative direction that is substantially parallel and / or coaxial with the axial centerline of a component, and the term "circumferential direction" refers to a relative direction around the axial centerline of a component.

[0017] Approximating terms such as "about", "substantially", and "essentially" are not limited to the exact numerical values described. In at least some instances, the approximating expression corresponds to the accuracy of the instrument for measuring the value or the accuracy of the method or machine for constructing or manufacturing the component and / or system. In at least some instances, the approximating expression corresponds to the accuracy of the instrument for measuring the value or the accuracy of the method or machine for constructing or manufacturing the component and / or system. For example, the approximating expression 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 defining the numerical range. When used with respect to an angle or direction, such terms include within ±10 degrees of the angle or direction described. For example, "substantially vertical" includes a direction within 10 degrees in either direction (e.g., clockwise or counterclockwise) from vertical.

[0018] Terms such as "coupling", "fixing", or "attaching" mean not only direct coupling, fixing, or attaching, but also indirect coupling, fixing, or attaching through one or more intermediate parts or features, unless otherwise described in this specification. Terms such as "direct coupling", "direct fixing", "direct attaching", etc. mean that the first component is joined to the second component without an intervening structure. The terms "comprising", "including", and "having" as used in this specification are inclusive of non-exclusive inclusion. For example, a process, method, article, or apparatus comprising the recited features is not necessarily limited to those features, and may include other features not explicitly recited and not inherent to such process, method, article, or apparatus.

[0019] In this specification and the claims, a numerical limitation range includes any sub-range included in that range, unless otherwise described or apparent from the context. For example, all the ranges disclosed in this specification include upper and lower limits, and the upper and lower limits can be combined independently of each other.

[0020] The term "premixing" as used in this specification can be used to represent a component, passage, or cavity upstream of each combustion zone where mixing occurs inside. For example, "premixing" can be used to represent a component, passage, or cavity where two types of fluids (such as fuel and air) are mixed together and then discharged from such component, passage, or cavity (e.g., into the combustion zone).

[0021] Referring now to the drawings, FIG. 1 shows a schematic view of an embodiment of a turbomachine, which in the embodiment shown in this figure is a gas turbine engine 10. In this specification, industrial or land-based gas turbines are described and explained, but the present disclosure is not limited to land-based and / or industrial gas turbine engines unless otherwise specified in the claims. For example, the technology described herein can be used in any type of turbomachine, including but not limited to steam turbines, aircraft gas turbines, or marine gas turbines.

[0022] As shown in the figure, the gas turbine engine 10 generally includes an intake section 12, a compressor section 14 disposed downstream of the intake section 12, a plurality of combustors 17 (see FIG. 2) within a combustor section 16 disposed downstream of the compressor section 14, a turbine section 18 disposed downstream of the combustor section 16, and an exhaust section 20 disposed downstream of the turbine section 18. Further, the gas turbine engine 10 may include one or more shafts 22 coupling the compressor section 14 and the turbine section 18. The shaft 22 may be coupled to a generator (not shown) for power generation.

[0023] The compressor section 14 generally includes a plurality of rotor disks 24 (one of which is shown) and a plurality of rotor blades 26 extending radially outward and connected from each rotor disk 24. Each rotor disk 24 is coupled to a shaft 22 passing through the compressor section 14 or forms part of the shaft 22. The compressor section 14 further includes a plurality of stationary blades (not shown), which are arranged in a plurality of stages together with the rotor blades 26 to direct the flow to the rotor blades 26.

[0024] The turbine section 18 generally includes a plurality of rotor disks 28 (one of which is illustrated) and a plurality of rotor blades 30 extending radially outwardly from and connected to each rotor disk 28. Each rotor disk 28 is coupled to or forms part of a shaft 22 that passes through the turbine section 18. The turbine section 18 further includes an outer casing 31 that circumferentially surrounds a portion of the shaft 22 and the rotor blades 30, and at least partially defines a hot gas path 32 through the turbine section 18. The turbine section 18 further includes a plurality of stationary blades (not shown) that are arranged in a plurality of stages together with the rotor blades 30 and direct the flow to the rotor blades 30.

[0025] During operation, a working fluid such as air flows from the intake section 12 into the compressor section 14, where the air is gradually compressed by a plurality of compressor stages of the rotor blades and stationary blades and the compressed air 15 is supplied to the combustor 17 of the combustor section 16. The compressed air 15 is mixed with fuel and burned in each combustor to generate combustion gas 34. The combustion gas 34 flows from the combustor section 16 through the hot gas path 32 into the turbine section 18, where energy (kinetic and / or thermal) is transferred from the combustion gas 34 to the rotor blades 30 to rotate the shaft 22. The mechanical rotational energy can then be used to drive the compressor section 14 and / or for power generation. The combustion gas 34 exiting the turbine section 18 can then be discharged from the gas turbine engine 10 via the exhaust section 20.

[0026] FIG. 2 is a schematic view of a combustor 17 and can be included in a can annular combustion system 16 for a gas turbine 10. In a can annular combustion system, a plurality (e.g., 8, 10, 12, 14, 16 or more) of combustors 17 are arranged in an annular array around a shaft 22 that connects the compressor section 14 to the turbine section 18.

[0027] As shown in FIG. 2, the combustor 17 may define an axial direction A extending along the axial centerline 170. The combustor may also define a circumferential direction C extending around the axial direction A and the axial centerline 170. The combustor 17 may further define a radial direction R orthogonal to the axial direction A and the axial centerline 170.

[0028] 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 the outer sleeve 48 (i.e., circumferentially surrounded by the outer sleeve 48), and an annulus 47 is formed therebetween. The combustion liner 46 may contain combustion gas and convey it to the turbine section 18. The combustion liner 46 defines a combustion chamber 70 where combustion occurs. As shown in FIG. 2, the combustion liner 46 may extend between the fuel nozzle 40 and the rear 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, like many conventional combustion systems. Alternatively, the combustion liner 46 may have an integral (or "unibody") structure in which the generally cylindrical portion and the tapered portion are integrated with each other. Thus, all descriptions of the combustion liner 46 herein include both conventional combustion systems having separate liners and transition pieces and combustion systems having a unibody liner. Further, the present disclosure is equally applicable to a combustion system (also referred to as a "transition nozzle" or "integrated outlet piece") in which the transition piece of the turbine section 18 and the first-stage nozzle are integrated.

[0029] FIG. 2 shows 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 further described herein. One or more fuel nozzles 40 may be disposed at the front end of the combustor 17. Fuel can be sent into the fuel nozzle 40 through a fuel supply conduit 38 extending through the end cover 42. The fuel nozzle 40 conveys fuel and compressed air 15 to the 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.

[0030] 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 an impingement hole proximate the rear frame 118) and travels toward the end cover 42, and the compressed air 15 within the annulus 47 flows in a direction opposite to that of the combustion gas 172 (reference numeral 34 in FIG. 1) within 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.

[0031] In some embodiments, the outer sleeve 48 may include a flow sleeve and an impingement sleeve coupled to each other. The flow sleeve may be disposed at the front end, and the impingement sleeve may be disposed at the rear end. Alternatively, the outer sleeve 48 may have a unitary (or "unisleeve") structure in which the flow sleeve and the impingement sleeve are integrally formed with each other axially. As described above, the description of the outer sleeve 48 herein is intended to encompass both a conventional combustion system having separate flow and impingement sleeves and a combustion system having a unisleeve outer sleeve.

[0032] The front 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 can be of any type, such as a bundled-tube fuel nozzle or a swirler nozzle (often referred to as a "swozzle"). The fuel nozzles 40 can be disposed within the head-end air plenum 122 that is at least partially defined by the front casing 50. In many embodiments, the fuel nozzles 40 can extend from the end cover 42. For example, each fuel nozzle 40 can be coupled to the rear face of the end cover 42 via a flange (not shown). As shown in FIG. 2, one or more fuel nozzles 40 can be partially surrounded by the combustion liner 46. The rear or downstream end of the fuel nozzles 40 penetrates or collectively defines the cap plate 44 that defines the upstream end of the combustion chamber 70.

[0033] The fuel nozzles 40 can 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 can be a fuel mixture that includes natural gas (such as methane, ethane, propane, or other suitable natural gas) and / or hydrogen. In other embodiments, the first fuel 158 can be pure natural gas or pure hydrogen (e.g., 100% hydrogen, which may or may not contain a certain amount of impurities) 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 can be mixed together within the fuel nozzles 40 to form a first mixture of the compressed air 15 and the first fuel 158 before being ejected (or injected) into the primary combustion zone 72 by the fuel nozzles 40.

[0034] The front casing 50 may be fluidly and mechanically connected to the 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) at the downstream end of the outer sleeve 48 (indicated by the arrow near the rear frame 118). The compressed air moves upstream through the annulus 47, reverses at the end cover 42, and enters the fuel nozzle 40 to cool the head end. 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 rear end of the combustor 17. The compressed air 15 moves upstream from the rear end of the combustor 17 to the head-end air plenum 122, where the compressed air 15 reverses direction and enters the fuel nozzle 40.

[0035] In an exemplary embodiment, the fuel injection assembly 80 is provided to send a second fuel / air mixture from the primary combustion zone 72 to the secondary combustion zone 74 downstream therefrom. For example, a second flow of fuel and air may be introduced into the secondary combustion zone 74 by one or more fuel injectors 200.

[0036] The primary combustion zone 72 and the secondary combustion zone 74 may each be part 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 outlet of the fuel nozzle 40 to the fuel injector 200, and the secondary combustion zone 74 may be defined from the fuel injector 200 to the rear frame 118. In this configuration, the most forward boundary of the fuel injector 200 may define the end of the primary combustion zone 72 and the start of the secondary combustion zone 74 (e.g., the axial position at which the second flow of fuel and air is introduced).

[0037] A combustion system having combustion zones axially spaced apart in this manner is described as an "axial fuel staging" (AFS) system. The fuel injection assemblies 80 may be circumferentially spaced apart from each other 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 that are circumferentially spaced apart from each other and configured to inject a 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 (e.g., 1, 2, 3, or up to 10) of fuel injection assemblies 80.

[0038] As shown in FIG. 2, each fuel injection assembly 80 may include a fuel injector 200 and a boss 300 that is 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 the radially outer surface of the outer sleeve 48, and the boss 300 may be coupled to the radially outer surface of the combustion liner 46. The boss 300 may be radially spaced apart from the fuel injector 200. As will be described in more detail below, the boss 300 may be in fluid communication with the annulus 47, and the fuel injector 200 may be in fluid communication with the high pressure plenum 66.

[0039] 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 device 152 configured to supply a second fuel 160 to the fuel injector 200 via the fuel supply conduit 102. The second fuel supply device 152 may be the same as or different from the first fuel supply device 150 such that the fuel injector 200 is supplied with the same fuel 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 contain a certain amount of impurities) 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 be mixed together within the fuel injector 200 to form a mixture of the compressed air 15 and the second fuel 160 before being injected into the boss 300, and this mixture may be further mixed (or diluted) with the air from the annulus 47 before being injected into the secondary combustion zone 74.

[0040] Referring now to FIG. 3, an enlarged perspective view of a portion of the combustor 17 and the fuel injection assembly 80 according to an embodiment of the present disclosure is shown. As shown in the figure, 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 the 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 the boss 300.

[0041] In many embodiments, the body 204 of the fuel injector 200 may extend along an axial centerline 252 between a front end wall 210 and a rear end wall 212. In many embodiments, the axial centerline 252 of the fuel injector 200 may generally be aligned with the axial direction A of the combustor 17 (or may be slightly inclined with respect to the axial direction A of the combustor 17). The side walls 214 may extend generally axially between the front end wall 210 and the rear end wall 212 with respect to the axial centerline 252 of the fuel injector 200. In many embodiments, the front end wall 210 and the rear end wall 212 may each include a straight portion 216 and an inclined portion 218. The straight portion 216 is oriented generally perpendicular to the axial centerline 252, and the inclined portions 218 each extend between the straight portion 216 and the respective side walls 214.

[0042] The conduit fitting 215 may extend outwardly from the front end wall 210 of the body 204 along the axial centerline 252. In particular, the conduit fitting 215 may extend outwardly along the axial centerline 252 of the straight portion 216 of the front end wall 210. The conduit fitting 215 may be fluidly coupled to the fuel supply conduit 102 so as to receive the 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 such that the conduit fitting 215 can function as described herein.

[0043] 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 a front end wall 210, a rear end wall 212, and side walls 214. The debris filter 400 may be defined with a plurality of holes 402 (FIGS. 4 and 5) therethrough to enable fluid communication between the high-pressure plenum 66 and the fuel injector 200. The plurality of holes 402 may be sized to prevent debris (such as soot or other debris) from entering the fuel injector 200, which advantageously prevents clogging of the premix tubes 226 and their respective fuel ports 240. Further, the debris filter 400 may function as an inlet flow regulator. That is, the debris filter 400 may function to reduce the non-uniformity of the compressed air before the compressed air from the high-pressure plenum 66 enters the fuel injector 200.

[0044] FIG. 4 shows a cross-sectional view taken along the line 4-4 of the combustor 17 shown in FIG. 3 according to an embodiment of the present disclosure. FIG. 5 shows a cross-sectional view of another embodiment of the boss 300 attached to the combustor 17. As shown in FIGS. 4 and 5, the combustor 17 may include a combustion liner 46 that defines a combustion chamber 70 including a secondary combustion zone 74. The outer sleeve 48 may be disposed 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 may be disposed within the high-pressure plenum 66 (FIG. 2), including the fuel injection assembly 80. The annulus 47 may be in fluid communication with the high-pressure plenum 66 via one or more impingement openings 90. The impingement openings 90 may be oriented and dimensioned to cause high-pressure air 92 from the high-pressure plenum 66 to impinge on the outer surface of the combustion liner 46. During the impingement process, the high-pressure air 92 experiences a pressure drop as it passes through the impingement openings 90 to become low-pressure air 94 and receives energy transfer by removing heat from the combustion liner 46 (i.e., the low-pressure air 94 picks up heat). The low-pressure air 94 may be supplied to the fuel injector 200 as described below.

[0045] The fuel injection assembly 80 includes a fuel injector 200, a boss 300, and a debris filter 400. The fuel injection assembly 80 may include an insert 600 removably coupled to the boss 300. The fuel injector 200 may be coupled to the outer sleeve 48 (e.g., via one or more fasteners 208), and the fuel injector 200 may extend radially outward from the outer sleeve 48 toward the high-pressure plenum 66. The boss 300 may be fixedly coupled to the combustion liner 46 (e.g., via an annular weld joint 302) and may be disposed within the annulus 47. The insert 600 can be removably coupled to the boss 300 by any method, such as one or more fasteners, friction fit, or other means. The insert 600 may be inserted into an opening defined by the boss 300. In some embodiments, the insert 600 and the boss 300 may be integrally formed as a single part (e.g., a monolithic part). However, forming the boss 300 and the insert 600 separately allows the insert 600 to be easily removed, repaired, and / or replaced without damaging the combustor 17 or the fuel injection assembly 80.

[0046] In many embodiments, the insert 600 may include a flange portion 304 and an annular wall portion 306. The annular wall portion 306 may define a mixing flow path 312 that extends along a central axis 350. The central axis 350 may be disposed at the center of the mixing flow path 312 and may be oriented substantially radially (e.g., substantially parallel to the radial direction R of the combustor 17). The flange portion 304 may extend substantially axially and circumferentially, and the annular wall portion 306 may extend from the flange portion 304 substantially axially radially (i.e., substantially perpendicular to the flange portion 304) to the end portion 313. The flange portion 304 may be fixedly coupled to the combustion liner 46 (e.g., via an annular weld joint 302).

[0047] The flange portion 304 may partially define the combustion chamber 70. For example, the flange portion 304 may include a radially outer surface 305 and a radially inner surface 309. The radially inner surface 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., the exhaust gas 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 portion 310. The annular edge portion 310 may be the end of the flange portion 304. In some embodiments, the annular edge portion 310 may be welded to the combustion liner 46 (e.g., via an annular weld joint 302). Alternatively, the flange portion 304 may be removably coupled to the boss 300, for example, by means of fasteners (such as bolts), friction fitting, an interlock function, etc. The radial thickness of the flange portion 304 may be greater than the radial thickness of the combustion liner 46, and the radially outer surface 305 of the flange portion 304 is radially spaced from the radially outer surface of the combustion liner 46.

[0048] The insert 600 may define a mixing flow path 312, and the mixing flow path 312 may be substantially rectangular (or stadium-shaped as shown in FIG. 6). In other words, its side walls may be longer than the end walls such that the mixing flow path 312 is elongated in the axial direction A, and the fuel injection assembly 80 can increase the fuel / air introduction amount without substantially obstructing most of the annulus 47.

[0049] As shown in FIGS. 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. Also, the radially outer wall 220 and the radially inner wall 222 may extend between a front end wall 210 (FIG. 3), a rear end wall 212 (FIG. 3), and a side wall 214 of the fuel injector 200. In this way, the fuel plenum 224 can be comprehensively defined by the radially outer wall 220, the radially inner wall 222, the front end wall 210, the rear end wall 212, and the side wall 214. The fuel plenum 224 can receive the fuel flow through a conduit joint 215 (FIG. 3).

[0050] In an exemplary embodiment, the fuel injector 200 may further include a plurality of premixing tubes 226 that extend along an injection axis 228 from an inlet end 230 on the radially outer wall 220, through the fuel plenum 224 and the radially inner wall 222, to an outlet end 232. As shown in the figure, the premixing tubes 226 may extend radially inwardly beyond the radially inner wall 222 to each outlet end 232, or the outlet ends 232 of some or all of the premixing tubes 226 may be in the same plane as the radially inner wall. Each of the premixing tubes 226 may define a premixing passage 234 that extends from an inlet at the inlet end 230 to an outlet at the outlet end 232. In many embodiments, the injection axis 228 of each premixing tube 226 may be the centerline of the premixing tube 226. In many embodiments, each of the plurality of premixing tubes 226 may include one or more fuel ports 240 that fluidly connect the fuel plenum 224 to the premixing passage 234. For example, as shown in FIG. 4, each premixing passage 234 may include two fuel ports 240 (e.g., a front fuel port and a rear fuel port) that are diametrically opposed to each other, which advantageously provides uniform fuel distribution within the premixing passage 234.

[0051] In various embodiments, the plurality of premixing tubes 226 may be fluidly coupled to a high-pressure air source (such as the high-pressure plenum 66 shown in FIG. 5). For example, the premixing flow path 234 may receive a flow of high-pressure air 92 (compressed air 15 in FIG. 2) from the high-pressure plenum 66 through an inlet at the inlet end 230. The mixing flow path 312 may be fluidly coupled to a low-pressure air source (such as the annulus 47). The mixing flow path 312 may receive a mixture of high-pressure air 92 and fuel from each of the premixing tubes 226, and the premixing tubes 226 are angled to direct the flow into the mixing flow path 312. Additionally, the mixing flow path 312 may receive low-pressure air 94 from the annulus 47.

[0052] The insert 600 may be disposed radially spaced from the fuel injector 200 such that a radial gap 272 is defined between the insert 600 and the fuel injector 200. The multi-fluid interaction region 600 may be defined between the outlet of the outlet end 232 of the premixing tube 226 and the inlet of the mixing flow path 312. For example, the multi-fluid interaction region 600 may receive a mixture of high-pressure air 92 and fuel from each of the premixing tubes 226. Additionally, the multi-fluid interaction region 600 may receive low-pressure air 94 from the annulus 47, which advantageously further mixes the fuel / air and dilutes the fuel towards a desired fuel / air ratio before sending the fuel / air to the combustion chamber 70.

[0053] As shown in FIGS. 4 and 5, the injection axis 228 of each premixing tube 226 may be inclined towards the central axis 350 of the mixing flow path 312. For example, each premixing tube 226 may be oblique with respect to the radial direction R such that the injection axis 228 is angled with respect to the central axis 350 that is oriented substantially radially in the mixing flow path 312. In this way, the outlet end 232 of each premixing tube 226 may be closer to the central axis 350 of the mixing flow path 312 than the inlet end 230. The outer premixing tubes 226 (such as those farther from the injection axis 350) may be more inclined than the inner premixing tubes 226 (such as those closer to the injection axis 350).

[0054] As shown in FIGS. 4 to 6, the insert 600 may define a plurality of partial direct injectors 500 (or lean direct injectors) that are spaced apart from each other and disposed around (or collectively surround) the mixing flow path 312. A "partial direct injector" refers to an injector that directly injects air and fuel (e.g., partial air / fuel) into the combustion chamber 70 without complete mixing.

[0055] Each partial direct injector 500 may include a localized mixing chamber for fuel and air, and the fuel and air are injected into the combustion chamber 70 around the mixing flow path 312. The plurality of partial direct injectors 500 may inject only a small portion of the fuel / air supplied to the fuel injection assembly 80. For example, about 60% to about 95% of the fuel for the fuel injection assembly 80 may be supplied to the fuel injector 200 (e.g., the fuel plenum 224), and the remainder of the fuel for the fuel injection assembly 80 (e.g., about 5% to about 40%) may be supplied to the plurality of partial direct injectors 500. Thus, the plurality of partial direct injectors 500 may collectively define a total volume of about 5% to about 30% (or about 10% to about 20%, etc.) of the volume of the mixing flow path 312.

[0056] As shown in FIG. 4, one or more of the plurality of partial direct injectors 500 may be defined in the flange portion 304 of the insert 600. For example, one or more of the partial direct injectors 500 may be completely defined in the flange portion 304 of the insert 600. In some embodiments, all of the partial direct injectors 500 may be defined in the flange portion 304 of the insert 600. The partial direct injector 500 may be defined in the flange portion 304 between the radially outer surface 305 and the radially inner surface 309. In particular, each partial direct injector 500 may extend within the flange portion 304 from an outlet 502 defined in the radially inner surface 309 to a fuel injection orifice 504 defined radially inward of the radially outer surface 305.

[0057] In other embodiments, as shown in FIG. 5, one or more of the plurality of partial direct injectors 500 may be defined in the annular wall portion 306 of the insert 600. For example, one or more of the partial direct injectors 500 may be completely defined in the annular wall portion 306 of the insert 600. In some embodiments, all of the partial direct injectors 500 may be defined in the annular wall portion 306 of the insert 600. The partial direct injector 500 may be defined in the annular wall portion 306 between the terminal end portion 313 of the annular wall portion 306 and the radially inner surface 309. In particular, each partial direct injector 500 may extend within the annular wall portion 306 from an outlet 502 defined in the radially inner surface 309 to a fuel injection orifice 504 defined radially inward of the radially outer surface 305.

[0058] As shown in FIGS. 4 and 5, each partial direct injector 500 may extend to an outlet 502 on the radially inner surface 309 of the insert 600. Further, each partial direct injector 500 may be defined in the insert 600 by a boundary surface 518. The boundary surface 518 may include a cylindrical portion 520 and a tapered portion 522. The cylindrical portion 520 extends from the outlet 502 to the tapered portion 522, and the tapered portion 522 may extend from the cylindrical portion to the fuel injection orifice 504. Note that the tapered portion 522 may be conical. That is, the diameter of the tapered portion 522 may converge as the tapered portion 522 extends radially from the cylindrical portion 520 to the fuel injection orifice 504.

[0059] In an exemplary embodiment, the insert 600 may further define an air supply circuit 506 and a fuel supply circuit 508, each in fluid connection with a plurality of partial direct injectors 500. The air supply circuit 506 and the fuel supply circuit 508 may be fluidly coupled separately from the plurality of direct injectors, and the air supply circuit 506 and the fuel supply circuit 508 are fluidly separated, but each supplies fluid for mixing / injecting into the combustion chamber 70 to the partial direct injectors 500. The air supply circuit 506 may be fluidly coupled to an air supply system. In an exemplary embodiment, as shown in the figures, the air supply system may be the annulus 47. In other embodiments (not shown), the air supply system may be a high-pressure plenum 66 or another air source. Similarly, the fuel supply circuit 508 may be fluidly coupled to a fuel supply system 510. In some embodiments, the fuel supply circuit 508 may be fluidly connected to a fuel injector 200 (e.g., a fuel plenum 224 and / or a conduit fitting 215 such that fuel is supplied to both the fuel injector 200 and / or the partial direct injector 500). In other embodiments, the fuel supply system 510 may be a stand-alone fuel supply system 510 fluidly coupled independently to the fuel supply circuit 508 within the insert 600.

[0060] As shown in the figures, the air supply circuit 506 includes an air inlet passage 512, an air plenum 514, and an air outlet passage 516. As shown in the figures, in some embodiments, the air inlet passage 512 may extend from an inlet on the annular edge 310 (FIG. 6) and / or an inlet on the radially outer surface 305 (FIGS. 4 and 5) to the air plenum 514. The air plenum 514 may be annular in many embodiments (as shown in FIG. 6) and may be fluidly coupled (e.g., directly fluidly coupled) to the air inlet passage 512.

[0061] The fuel supply circuit 508 includes one or more fuel inlet passages 536. Each fuel inlet passage 536 of the one or more fuel inlet passages 536 may be fluidly coupled to each partial direct injector 500 of the plurality of partial direct injectors. In particular, each fuel inlet passage 536 of the one or more fuel inlet passages may extend from the terminal end 313 of the annular wall portion 306 to the fuel injection orifice 504 of each partial direct injector 500. Each fuel inlet passage 536 may extend substantially axially-radially within the insert 600 immediately upstream of the fuel injection orifice 504 of each partial direct injector 500 to which the fuel inlet passage 536 is fluidly coupled, and the fuel inlet passage 536 introduces (or guides) fuel to the partial direct injector 500 along the radial direction R.

[0062] In particular, as shown in FIG. 4, the fuel inlet passage 536 may include a first portion 524, a second portion 526 (which may extend substantially perpendicular to the first portion), and a third portion 528. The first portion 524 of the fuel inlet passage 536 may extend substantially axially-radially from the terminal end 313 of the fuel inlet passage 536 to the second portion 526. The second portion 526 of the fuel inlet passage 536 may extend from the first portion 524 to the third portion 528. The second portion 526 may be substantially perpendicular to one or both of the first portion 524 and the third portion 528, or the second portion 526 may be inclined (e.g., at an angle other than perpendicular) with respect to the first portion 524. The third portion 528 may extend substantially axially-radially from the second portion 526 to the fuel injection orifice 504 of the partial direct injector 500. In other embodiments, as shown in FIG. 5, the fuel inlet passage 536 may extend completely radially from the terminal end 313 to the fuel injection orifice 504 of the partial direct injector 500.

[0063] Referring now to FIG. 6, there is shown a cross-sectional view taken along line 6-6 of the insert 600 shown in FIG. 4 according to an embodiment of the present disclosure. As shown in the figure, the insert 600 may extend between a front end 301 and a rear end 303. The insert 600 can define a mixing channel 312, which can generally be shaped as a stadium (e.g., a rectangle with rounded ends or a rectangle with rounded corners). A plurality of partial direct injectors 500 may be defined within the insert 600 and may be disposed around the mixing channel 312 such that the plurality of partial direct injectors 500 collectively surround the mixing channel 312. The plurality of partial direct injectors 500 may be disposed closer to the mixing channel than the annular edge 310 of the boss.

[0064] As shown in the figure, the air supply circuit 506 includes one or more front air inlet passages 512A, one or more rear air inlet passages 512B, an air plenum 514, and a plurality of air outlet passages 516, each being fluidly connected to a respective partial direct injector 500. As shown in the figure, in some embodiments, the air inlet passages 512A, 512B may each extend from an inlet at the annular edge 310 to the air plenum 514. The air plenum 514 may be annular and may surround the mixing channel 312. In an exemplary embodiment, at least two air outlet passages 516 may be fluidly connected to each partial direct injector 500 of the plurality of partial direct injectors 500. In the case of an embodiment having two air outlet passages 516 fluidly connected to a single partial direct injector 500, the two air outlet passages 516 may be diametrically opposed (e.g., 180° apart) with respect to the partial direct injector 500. In an embodiment having more than two air outlet passages 516 connected to a single partial direct injector 500 (not shown), the air outlet passages 516 may be equally spaced around the partial direct injector 500. Thereby, air is evenly distributed within the partial direct injector 500 to improve mixing with fuel.

[0065] Referring now to FIG. 7, there is shown a cross-sectional view taken along line 7-7 of FIG. 6 of the insert 600 according to an embodiment of the present disclosure. As shown in the figure, the partial direct injector 500 can be defined in the insert 600 by the boundary surface 518. The partial direct injector 500 can extend radially between an outlet 502 on the radially inner surface 309 of the insert 600 and a fuel injection orifice 504 (or inlet). The boundary surface 518 may include a first cylindrical portion 520, a tapered portion 522, and optionally a second cylindrical portion 530. The first cylindrical portion 520 defines a first diameter, and the second cylindrical portion 530 defines a second diameter. The second diameter is smaller than the first diameter. When the second cylindrical portion 530 is present, it can extend radially from the fuel injection orifice 504 to the tapered portion 522 and can be used to facilitate the additive manufacturing of the insert 600 (or the boss 300 if the boss 300 includes the partial direct injector 500). The tapered portion 522 increases in diameter as the tapered portion 522 extends radially from the second cylindrical portion 530 to the first cylindrical portion 520. Note that the tapered portion 522 may be conical.

[0066] As shown in the figure, the air outlet passage 516 of the air supply circuit 506 can extend to the tapered portion 532 of the boundary surface 518. In particular, the two air outlet passages 516 can extend to the tapered portion 532 of the boundary surface 518. The two air outlet passages 516 may be diametrically opposed (e.g., 180° apart) with respect to the partial direct injector 500, introducing air uniformly to the partial direct injector 500. The fuel inlet passage 536 of the fuel supply circuit 508 can extend to the partial direct injector 500 substantially perpendicular to the air outlet passage 516. Thereby, advantageously, a cross-flow between air / fuel can be provided to increase mixing, improving the efficiency of the combustion process in the combustion chamber 70. In particular, the fuel inlet passage 536 can extend to the fuel injection orifice 504 (and / or the second cylindrical portion 530) to fluidly connect to the partial direct injector 500.

[0067] The partial direct injector 500 advantageously enables the combustor 17 to be operated with a large amount of hydrogen without causing flame holding problems within the axial fuel staging injector 80. For example, the fuel supplied to the fuel injection assembly 80 may be split between the fuel injector 200 and the partial direct injector 500, allowing for more localized mixing and efficient combustion.

[0068] In this specification, the present invention has been disclosed including its best mode, and has been described by way of examples to enable those skilled in the art to practice the manufacture, use, and method of the apparatus or system. The scope of patentability of the present invention is defined by the claims, and includes other examples that are obvious to those skilled in the art. Such other examples belong to the technical scope described in the claims if they have components that are not different in wording from the claims, or if they have equivalent components that have only non-essential differences from the wording of the claims.

[0069] Additional aspects of the present invention are set forth in the following embodiments section. [Embodiment Item 1] In a first aspect, 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, a boss configured to couple to a combustion liner of the combustor at a position axially and circumferentially aligned with the fuel injector, and an insert removably coupled to the boss. The insert includes a flange portion and an annular wall portion extending from the flange portion and defining a mixing flow path. The insert defines a plurality of partial direct injectors spaced apart from each other and disposed around the mixing flow path. [Embodiment Item 2] The fuel injection assembly according to Embodiment Item 1, wherein one or more of the plurality of partial direct injectors are defined in the flange portion of the insert. [Embodiment Item 3] The fuel injection assembly according to embodiment item 1 or embodiment item 2, wherein one or more partial direct injectors of a plurality of partial direct injectors are defined in the annular wall portion of the insert. [Embodiment item 4] The fuel injection assembly according to any one of embodiment items 1 to 3, wherein the insert defines an air supply circuit and a fuel supply circuit that are each fluidly connected to a plurality of partial direct injectors. [Embodiment item 5] The fuel injection assembly according to any one of embodiment items 1 to 4, wherein the air supply circuit includes an air inlet passage, an air plenum, and a plurality of air outlet passages, and each of the plurality of air outlet passages extends from the air plenum to each partial direct injector of the plurality of partial direct injectors. [Embodiment item 6] The fuel injection assembly according to any one of embodiment items 1 to 5, wherein the air plenum is annular. [Embodiment item 7] The fuel injection assembly according to any one of embodiment items 1 to 6, wherein each partial direct injector extends to an outlet on the radially inner surface of the flange portion of the insert. [Embodiment item 8] The fuel injection assembly according to any one of embodiment items 1 to 7, wherein each partial direct injector is defined in the insert by a boundary surface, and the boundary surface includes a cylindrical portion and a tapered portion. [Embodiment item 9] The fuel injection assembly according to any one of embodiment items 1 to 8, wherein the air outlet passage of the air supply circuit extends to the tapered portion of the boundary surface. [Embodiment item 10] The fuel injection assembly according to any one of embodiment items 1 to 9, wherein the fuel inlet passage of the fuel supply circuit extends to the partial direct injector substantially perpendicular to the air outlet passage. [Embodiment item 11] In another aspect of the present disclosure, a combustor is provided. The combustor includes one or more fuel nozzles, a combustion liner extending downstream of the fuel nozzles, an outer sleeve spaced apart from the combustion liner and surrounding it to define an annulus therebetween, and a fuel injection assembly disposed downstream of the one or more fuel nozzles. The fuel injection assembly includes a fuel injector coupled to the outer sleeve of the combustor, a boss coupled to the combustion liner of the combustor and axially and circumferentially aligned with the fuel injector, and an insert removably coupled to the boss. The insert includes a flange portion and an annular wall portion extending from the flange portion to define a mixing flow path. The insert defines a plurality of partial direct injectors disposed around the mixing flow path and spaced apart from each other. [Embodiment Item 12] The combustor according to Embodiment Item 11, wherein one or more of the plurality of partial direct injectors are defined in the flange portion of the insert. [Embodiment Item 13] The combustor according to Embodiment Item 11 or Embodiment Item 12, wherein one or more of the plurality of partial direct injectors are defined in the annular wall portion of the insert. [Embodiment Item 14] The combustor according to any one of Embodiment Items 11 to 13, wherein the insert defines an air supply circuit and a fuel supply circuit each fluidly connected to the plurality of partial direct injectors. [Embodiment Item 15] The combustor according to any one of Embodiment Items 11 to 14, wherein the air supply circuit includes an air inlet passage, an air plenum, and a plurality of air outlet passages each extending from the air plenum to a respective one of the plurality of partial direct injectors of the plurality of partial direct injectors. [Embodiment Item 16] The combustor according to any one of Embodiment Items 11 to 15, wherein the air plenum is annular. [Embodiment Item 17] The combustor according to any one of Embodiment Items 11 to 16, wherein each partial direct injector extends to the radially inner surface outlet of the flange portion of the insert. [Embodiment Item 18] The combustor according to any one of Embodiment Items 11 to 17, wherein each partial direct injector is defined in the insert by a boundary surface, and the boundary surface includes a cylindrical portion and a tapered portion. [Embodiment Item 19] The combustor according to any one of Embodiment Items 11 to 18, wherein the air outlet passage of the air supply circuit extends to the tapered portion of the boundary surface. [Embodiment Item 20] The combustor according to any one of Embodiment Items 11 to 19, wherein the fuel inlet passage of the fuel supply circuit extends to the partial direct injector substantially perpendicular to the air outlet passage.

Explanation of Signs

[0070] 10 Gas turbine engine 17 Combustor 40 Fuel nozzle 46 Combustion liner 47 Annulus 48 Outer sleeve 70 Combustion chamber 80 Fuel injection assembly 200 Fuel injector 300 Boss 304 Flange portion of the insert 305 Radially outer surface of the flange portion 306 Annular wall portion of the insert 309 Radially inner surface of the flange portion 312 Mixing flow path 313 Termination end of the annular wall portion 500 Partial direct injector 502 Outlet 504 Fuel injection orifice 506 Air supply circuit 508 Fuel supply circuit 512 Air inlet passage 514 Air plenum 516 Air outlet passage 518 Interface 520 First cylindrical portion of the interface 522 Taper portion of the interface 530 Second cylindrical portion of the interface 536 Fuel inlet passage 600 Insert

Claims

1. A fuel injection assembly (80) for a combustor (17) of a gas turbine engine (10), the fuel injection assembly (80) comprising: a fuel injector (200) configured to be coupled to an outer sleeve (48) of the combustor (17); a boss (300) configured to be coupled to a combustion liner (46) of the combustor (17) at a position axially and circumferentially aligned with the fuel injector (200); an insert (600) removably coupled to the boss (300); wherein the insert (600) includes a flange portion (304) and an annular wall portion (306) extending from the flange portion (304), the annular wall portion (306) defining a mixing flow path (312), and the insert (600) defines a plurality of partial direct injectors (500) spaced apart from each other and disposed around the mixing flow path (312). The fuel injection assembly (80).

2. The fuel injection assembly (80) according to claim 1, wherein one or more of the plurality of partial direct injectors (500) are defined in a flange portion (304) of the insert (600).

3. The fuel injection assembly (80) according to claim 1, wherein one or more of the plurality of partial direct injectors (500) are defined in an annular wall portion (306) of the insert (600).

4. The fuel injection assembly (80) according to claim 1, wherein the insert (600) defines an air supply circuit (506) and a fuel supply circuit (508) each fluidly connected to the plurality of partial direct injectors (500).

5. The fuel injection assembly (80) according to claim 4, wherein the air supply circuit (506) includes an air inlet passage (512), an air plenum (514), and a plurality of air outlet passages (516) each extending from the air plenum (514) to a respective one of the plurality of partial direct injectors (500).

6. The fuel injection assembly (80) according to claim 5, wherein the air plenum (514) is annular.

7. The fuel injection assembly (80) according to claim 1, wherein each partial direct injector (500) of the plurality of partial direct injectors (500) extends to an outlet (502) on the radially inner surface (309) of the flange portion (304) of the insert (600).

8. The fuel injection assembly (80) according to claim 1, wherein each partial direct injector (500) of the plurality of partial direct injectors (500) is defined in the insert (600) by a boundary surface (518), and the boundary surface (518) has cylindrical portions (520, 530) and a tapered portion (522).

9. The fuel injection assembly (80) according to claim 8, wherein an air outlet passage (516) of the air supply circuit (506) extends to the tapered portion (522) of the boundary surface (518).

10. The fuel injection assembly (80) according to claim 9, wherein a fuel inlet passage (536) of the fuel supply circuit (508) extends to each partial direct injector (500) of the plurality of partial direct injectors (500) substantially perpendicular to the air outlet passage (516).

11. A combustor (17), wherein the combustor (17) has one or more fuel nozzles (40), a combustion liner (46) extending downstream of the one or more fuel nozzles (40) and defining a combustion chamber (70), an outer sleeve (48) spaced apart from the combustion liner (46) and surrounding it, defining an annulus (47) between the outer sleeve (48) and the combustion liner (46), and a fuel injection assembly (80) disposed downstream of the one or more fuel nozzles (40), the fuel injection assembly (80) according to any one of claims 1 to 10. A combustor (17) comprising the above.

12. The combustor (17) according to claim 11, wherein the flange portion (304) of the insert (600) partially defines the combustion chamber (70), each partial direct injector (500) extends to an outlet (502) on the radially inner surface (309) of the flange portion (304) of the insert (600), and the outlet (502) is in fluid communication with the combustion chamber (70).

Images