Axial fuel stage injector with fuel injection in the same direction as high-pressure airflow

Abstract

To appropriately mix a highly reactive fuel such as hydrogen with air, thereby achieving low exhaust emissions and flame holding capability.SOLUTION: An axial fuel stage (AFS) injector includes a mixing member in which a mixing chamber having an inlet and an outlet in fluid communication with a combustion chamber of a combustor is defined. A high-pressure (HP) air-fuel injection member includes one or more rows of HP air-fuel injectors for introducing an air-fuel mixture into the mixing chamber. Each HP air-fuel injector includes two opposing side walls and an intermediate wall extending longitudinally between the two opposing side walls. The intermediate wall and each opposing side wall define elongated HP air outlets therebetween. A fuel plenum supplies fuel from a fuel source to a fuel injector defined at a radially inner end of the intermediate wall. Each elongated HP air outlet is configured to guide a flow of HP air from an HP air source toward the inlet of the mixing chamber in the same direction as a flow of fuel from one or more fuel injectors.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates generally to turbomachine combustors, and more particularly to axial fuel stage (AFS) injectors with fuel injection co-directional with high pressure airflow, and combustor and gas turbine systems including such AFS injectors. [Background technology]

[0002] A gas turbine system includes a combustion section that includes multiple combustors that combust fuel to generate a combustion gas flow that is converted to kinetic energy in a downstream turbine section. Current combustors include a head-end fuel nozzle assembly for burning the fuel in a primary combustion zone and axial fuel stage (AFS) injectors for burning the fuel in a secondary combustion zone downstream of the primary combustion zone. A portion of the supply air, for example from a compressor discharge casing, is delivered to the head-end fuel nozzle assembly and the AFS injectors through various flow paths. Current AFS injectors have challenges in adequately mixing highly reactive fuels, such as hydrogen, with air and achieving desirable low emissions and flame-holding capabilities. Summary of the Invention

[0003] All aspects, embodiments and features listed below may be combined in any technically possible manner.

[0004] One aspect of the disclosure encompasses an axial fuel stage (AFS) injector for a combustor of a gas turbine (GT) system, the AFS injector including: a mixing element having a mixing chamber defined therein, the mixing chamber having an inlet and an outlet, the outlet configured to be in fluid communication with a combustion chamber of the combustor; and a high-pressure (HP) air-fuel injection element including one or more rows of HP air-fuel injectors for directing an air-fuel mixture into the mixing chamber, each HP air-fuel injector having two opposing sidewalls and a longitudinally extending portion between the two opposing sidewalls. the intermediate wall, two opposing side walls and the intermediate wall, the intermediate wall and each opposing side wall defining an elongated high-pressure (HP) air jet therebetween; one or more fuel injectors defined at a radially inner end of the intermediate wall; and a fuel plenum defined in the intermediate wall, the fuel plenum configured to supply fuel from a fuel source to each of the one or more fuel injectors, each elongated HP air jet configured to direct a flow of HP air from the HP air source toward an inlet of the mixing chamber in the same direction as the flow of fuel from the one or more fuel injectors.

[0005] Another aspect of the present disclosure includes any of the above-described aspects, wherein the one or more rows of HP air-fuel injectors include a first row of HP air-fuel injectors and a second row of HP air-fuel injectors, and the HP air-fuel injection members include tapered deflector walls downstream of and between outlets of adjacent HP air jets of the first row of HP air-fuel injectors and the second row of HP air-fuel injectors.

[0006] Another aspect of the present disclosure includes any of the above aspects, wherein the one or more rows of HP air-fuel injectors include a first row of HP air-fuel injectors, a second row of HP air-fuel injectors, and a third row of HP air-fuel injectors between the first row of HP air-fuel injectors and the second row of HP air-fuel injectors.

[0007] Another aspect of the present disclosure includes any of the above-described aspects, wherein the HP air-fuel injectors of the third row of HP air-fuel injectors direct the air-fuel mixture in a direction parallel to the mixing chamber, and the HP air-fuel injectors of the first and second rows direct the air-fuel mixture at an acute angle relative to the direction parallel to the mixing chamber.

[0008] Another aspect of the present disclosure includes any of the above-described aspects, wherein the HP air nozzles of the third row of HP air-fuel injectors are transversely longer, relative to the axial direction of the AFS injectors, than the HP air nozzles of the first and second rows of HP air-fuel injectors.

[0009] Another aspect of the present disclosure includes any of the above aspects, wherein the HP air jets of the first row, second row, and third row of HP air-fuel injectors have the same length transversely relative to the axial direction of the AFS injector.

[0010] Another aspect of the present disclosure includes any of the above-described aspects, wherein the third row of HP air-fuel injectors is axially offset from the first row of HP air-fuel injectors and the second row of HP air-fuel injectors, and the HP air-fuel injection member further includes a tapered deflector wall downstream of and between the outlets of adjacent HP air jets of the first row of HP air-fuel injectors and the second row of HP air-fuel injectors.

[0011] Another aspect of the present disclosure includes any of the above aspects, and further includes recesses defined in the radially inner wall of the HP air-fuel injection member between a plurality of adjacent HP air-fuel injectors of at least one of the first row of HP air-fuel injectors and the second row of HP air-fuel injectors.

[0012] Another aspect of the present disclosure includes any of the above aspects, wherein the HP air-fuel injection member further includes one or more rows of HP air ejection slots circumferentially spaced from the one or more rows of HP air-fuel injectors for directing a separate flow of HP air from the HP air source toward the inlet of the mixing chamber.

[0013] Another aspect of the present disclosure includes any of the above aspects, wherein the HP air-fuel injection members include diverging openings downstream of each HP air-fuel injector.

[0014] Another embodiment of the present disclosure includes any of the above-described embodiments, wherein the two opposing side walls and the intermediate wall are joined at their longitudinal ends, and the two opposing side walls collectively have an elliptical cross-sectional shape.

[0015] Another aspect of the present disclosure includes any of the above aspects, wherein the intermediate wall has a teardrop-shaped cross-sectional shape with a bulbous end and a tip, and the one or more fuel injectors are at the tip.

[0016] Another aspect of the present disclosure includes any of the above aspects, wherein the one or more fuel injectors include a plurality of fuel injectors.

[0017] Another aspect of the present disclosure includes any of the above aspects, wherein the fuel plenum defined by the intermediate wall extends from one end of the intermediate wall to an opposite end of the intermediate wall.

[0018] Another aspect of the present disclosure includes any of the above-described aspects, wherein the flow of HP air also entrains low pressure (LP) air from an LP air source to direct LP air into the inlet of the mixing chamber along with the HP air.

[0019] Another aspect of the present disclosure includes any of the above-described aspects, wherein the HP air source is in direct fluid communication with a compressor discharge of the GT system, and the LP air source is in fluid communication with a cooling passage defined along at least a portion of a combustion liner of the combustor.

[0020] Another aspect of the present disclosure includes any of the above aspects, wherein the mixing element and the HP air-fuel injection element each include one or more mounting elements configured to receive fasteners that couple the mixing element and the HP air-fuel injection element to a combustion liner that defines the combustion chamber.

[0021] Another aspect of the present disclosure encompasses a combustor for a gas turbine system, the combustor comprising: a combustor body including a combustion liner; and a plurality of axially staged fuel (AFS) injectors facing the combustion liner, each AFS injector including a mixing element defining a mixing chamber therein, the mixing chamber having an inlet and an outlet, the outlet configured to be in fluid communication with a combustion chamber of the combustor; and a high-pressure (HP) air-fuel injection element including one or more rows of HP air-fuel injectors for directing an air-fuel mixture into the mixing chamber, each HP air-fuel injector having two opposing sidewalls and The mixing chamber includes an intermediate wall extending longitudinally between two opposing side walls, the intermediate wall and each opposing side wall defining an elongated high-pressure (HP) air outlet therebetween; one or more fuel injectors defined at a radially inner end of the intermediate wall; and a fuel plenum defined in the intermediate wall, the fuel plenum configured to supply fuel from a fuel source to each of the one or more fuel injectors, each elongated HP air outlet configured to direct a flow of HP air from the HP air source toward an inlet of the mixing chamber in the same direction as the flow of fuel from the one or more fuel injectors.

[0022] Another aspect of the present disclosure includes any of the above aspects, wherein the one or more rows of HP air-fuel injectors include a first row of HP air-fuel injectors, a second row of HP air-fuel injectors, and a third row of HP air-fuel injectors between the first row of HP air-fuel injectors and the second row of HP air-fuel injectors.

[0023] Another aspect of the present disclosure encompasses a gas turbine (GT) system comprising a compressor section, a combustion section operatively coupled to the compressor section, and a turbine section operatively coupled to the combustion section, the combustion section including one or more combustors including a combustor body including a combustion liner, a head-end fuel nozzle assembly at a forward end of the combustor body, and a plurality of axially staged fuel (AFS) injectors facing the combustor body downstream of the head-end fuel nozzle assembly, each AFS injector including a mixing element defining a mixing chamber therein, the mixing chamber having an inlet and an outlet, the outlet configured to be in fluid communication with a combustion chamber of the combustor, and one or more AFS injectors for directing an air-fuel mixture into the mixing chamber. and a HP air-fuel injection member including a row of HP air-fuel injectors, each HP air-fuel injector comprising two opposing side walls and an intermediate wall extending longitudinally between the two opposing side walls, the intermediate wall and each opposing side wall defining an elongated HP air outlet therebetween; one or more fuel injectors defined at a radially inner end of the intermediate wall; and a fuel plenum defined in the intermediate wall, the fuel plenum configured to supply fuel from a fuel source to each of the one or more fuel injectors, each elongated HP air outlet configured to direct a flow of HP air from the HP air source toward an inlet of the mixing chamber in the same direction as the flow of fuel from the one or more fuel injectors.

[0024] Two or more aspects described in this disclosure, including those described in the Summary of the Invention, may be combined to form embodiments not specifically described herein, i.e., all embodiments described in this application may be combined with each other.

[0025] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. [Brief explanation of the drawings]

[0026] These and other features of the present disclosure may be better understood by reference to the following detailed description taken in conjunction with the accompanying drawings, which set forth various embodiments of the present disclosure. [Figure 1] FIG. 1 is a functional block diagram of an exemplary gas turbine system that may be used with a combustor that includes axial fuel stage (AFS) injectors according to embodiments of the present disclosure. [Figure 2] FIG. 1 is a cross-sectional side view of a combustor including an AFS injector according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is a perspective, partially cross-sectional view of an AFS injector according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a cross-sectional view of the AFS injector of FIG. 3 taken along line 4-4 according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a cross-sectional view of the AFS injector of FIG. 3 taken along line 5-5 in accordance with an embodiment of the present disclosure. [Figure 6] FIG. 6 is a cross-sectional view of the AFS injector of FIG. 3 taken along line 6-6 in accordance with an embodiment of the present disclosure. [Figure 7] FIG. 2 is a perspective, partially cross-sectional view of an AFS injector according to another embodiment of the present disclosure. [Figure 8] FIG. 2 is a perspective, partially cross-sectional view of an AFS injector according to another embodiment of the present disclosure. [Figure 9] 1 is a schematic perspective view of a high-pressure air fuel injector for an AFS injector according to an embodiment of the present disclosure; FIG. [Figure 10] 1 is a schematic cross-sectional view of a high-pressure air fuel injector for an AFS injector according to an embodiment of the present disclosure; FIG. [Figure 11] FIG. 2 is an enlarged perspective cross-sectional view of an AFS injector according to an embodiment of the present disclosure. [Figure 12] FIG. 2 is an enlarged perspective cross-sectional view of an AFS injector according to another embodiment of the present disclosure. [Figure 13] FIG. 1B is a bottom view of a high-pressure air fuel injection member of an AFS injector according to various embodiments of the present disclosure. [Figure 14] FIG. 2 is an enlarged bottom view of a portion of a high-pressure air fuel injection member of an AFS injector according to various embodiments of the present disclosure. [Figure 15]FIG. 10 is an enlarged bottom view of a high-pressure air fuel injection member of an AFS injector according to another embodiment of the present disclosure. [Figure 16] FIG. 2 is a perspective, partially cross-sectional view of an AFS injector according to another embodiment of the present disclosure. [Figure 17] FIG. 17 is a cross-sectional view of the AFS injector of FIG. 16 taken along line 17-17 in accordance with an embodiment of the present disclosure. [Figure 18] FIG. 1 is a cross-sectional view of multiple parallel sintered metal layers of a mixing element or high-pressure air injection element of an AFS injector according to an embodiment of the present disclosure. [Figure 19] FIG. 1 is a schematic block diagram of an exemplary additive manufacturing system for additive manufacturing a mixing element and / or a high-pressure air injection element of an AFS injector according to an embodiment of the present disclosure.

[0027] The drawings of the present disclosure are not necessarily to scale. The drawings are intended to illustrate exemplary aspects of the present disclosure only and are not intended to limit the scope of the present disclosure. In the drawings, like reference numerals represent like elements between the drawings. DETAILED DESCRIPTION OF THE INVENTION

[0028] First, to clearly explain the present technology, it is necessary to select terminology when referring to and describing relevant machine components in the exemplary application of a turbomachine combustor and axial fuel stage (AFS) injector. Wherever possible, terms common in the art will be used consistent with their ordinary meaning. Unless otherwise noted, such terms should be interpreted broadly within the context of this application and the accompanying claims. It will be apparent to those skilled in the art that a component will often be referred to using several different or overlapping terms. What may be described as a single component in this specification may be described as consisting of multiple components in another context. Alternatively, what may be described as including multiple components in one place in this specification may be described as a single component in another place.

[0029] Additionally, several descriptive terms are used repeatedly in this specification, and it may be helpful to define these terms at the beginning of this section. These terms and their definitions are as follows, unless otherwise specified: As used herein, the terms "downstream" and "upstream" refer to directions with respect to fluid flow (e.g., the flow of working fluid through a turbomachine, or the flow of air through a combustor or AFS injector, or the flow of coolant through one of the turbomachine's subsystems). The term "downstream" corresponds to the direction in which the fluid is flowing, and the term "upstream" refers to the direction opposite to the flow (i.e., the direction from which it is flowing). The terms "forward" and "aft" refer to directions not further specified, with "forward" referring to the forward or compressor end of a turbomachine or combustor and "aft" referring to the aft or turbine end of a turbomachine or combustor.

[0030] The term "axial" refers to movement or position parallel to an axis (e.g., the axis of a combustor, AFS injector mixing chamber, or turbomachine). The term "radial" refers to movement or position perpendicular to an axis (e.g., the axis of a combustor or turbomachine). If a first component is closer to the axis than a second component, the first component is described herein as "radially inward" or "proximal to the axis" of the second component. Conversely, if a first component is located farther from the axis than the second component, the first component is described herein as "radially outward" or "distal to the axis" of the second component. Finally, the term "circumferential" refers to movement or position about an axis. As noted above, depending on the context, such terms may be applied relative to the axis of a combustor or the axis of a turbomachine.

[0031] Furthermore, certain descriptive terms are used repeatedly in this specification, as described below: The terms "first," "second," and "third" are used interchangeably to distinguish one component from another, and do not denote the location or importance of the individual components.

[0032] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the disclosure. As used herein, the singular "a," "an," or "an" refers to the plural unless the context clearly dictates otherwise. As used herein, the terms "comprises" and / or "includes" refer to the presence of stated features, integers, steps, operations, components, and / or parts, and do not exclude the presence or addition of one or more other features, integers, steps, operations, components, parts, and / or groups thereof. The terms "optional" or "optionally" mean that the event described following the term may or may not occur, or the feature described following the term may or may not be present, and such descriptions encompass both the occurrence of the event or the presence of the feature and the absence of the event or the absence of the feature.

[0033] When a component or layer is referred to as being "on," "engaged with," "connected to," "coupled to," or "attached to" another component or layer, it may be directly on, directly engaged with, connected to, coupled to, or attached to that other component or layer, or there may be intervening components or layers. In contrast, when a component is referred to as being "directly on," "directly engaged with," "directly connected to," or "directly coupled to" another component or layer, there are no intervening components or layers. Other terms used to describe relationships between components (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.) are to be interpreted similarly. As used herein, the term "and / or" encompasses any and all combinations of one or more of the listed items. The terms "coupled" and "attached" may be used interchangeably herein.

[0034] Embodiments of the present disclosure provide an axial fuel stage (AFS) injector for a combustor, as well as a combustor and gas turbine (GT) system including such an AFS injector. The AFS injector includes a mixing element having a mixing chamber defined therein. The mixing chamber includes an inlet and an outlet, the outlet configured to be in fluid communication with a combustion chamber of the combustor. The high-pressure (HP) air-fuel injection element includes one or more rows of HP air-fuel injectors for directing an air-fuel mixture into the mixing chamber. Each HP air-fuel injector includes two opposing sidewalls and an intermediate wall extending longitudinally therebetween, the intermediate walls defining an elongated high-pressure (HP) air outlet therebetween, one or more fuel injectors defined at radially inner ends of the intermediate walls, and a fuel plenum defined in the intermediate walls, the fuel plenum configured to supply fuel from a fuel source to each of the one or more fuel injectors. Each elongated HP air jet is configured to direct a flow of HP air from an HP air source toward an inlet of a mixing chamber co-directional with a flow of fuel from one or more fuel injectors, and the mixing chamber directs the air-fuel mixture into the combustion liner for combustion in a secondary combustion zone.

[0035] AFS injectors can optionally blend two air sources—one high-pressure air (e.g., compressor discharge air) and the other low-pressure air (e.g., post-impingement cooling air)—to reduce overall system pressure loss and improve air utilization efficiency in the combustor. In either case, AFS injectors can rapidly premix one or more air sources with highly reactive fuels, such as hydrogen, to achieve reduced emissions such as nitrogen oxides (NOx) and adequate flameholding. AFS injectors also achieve high fuel-air mixing, minimizing flow pressure loss and preventing fuel from entering the low-velocity airflow region. Furthermore, AFS injectors can be packaged in a relatively small form factor and attached to the combustion liner of the combustor body, allowing the combustor body to be attached to the GT system through a relatively small opening in the compressor discharge casing. AFS injectors can be additively manufactured to include multiple parallel sintered metal layers.

[0036] 1 illustrates a functional block diagram of an exemplary gas turbine (GT) system 90 that may incorporate various embodiments of a combustor 100 and axial fuel stage (AFS) injector 150 (FIG. 2) of the present disclosure. As shown, the GT system 90 generally includes an inlet section 102, which may include a series of filters, cooling coils, moisture separators, and / or other devices for cleaning or conditioning a working fluid (e.g., air) 104 entering the GT system 90. A working fluid 106 (air) flows to a compressor 108 in a compressor section 110, where kinetic energy is progressively added to the working fluid 106 to produce compressed, high-pressure (HP) air 112 (hereinafter referred to as "HP air 112" or "compressed air 112"). The HP air 112 is typically mixed with fuel 114A and / or 114B from a fuel source 116 to produce a combustible mixture in one or more combustors 100 of a combustion section 120 operatively coupled to the compressor section 110. The combustible mixture is combusted to produce high temperature and pressure combustion gases 122.

[0037] The combustion gases 122 flow through a turbine 128 of a turbine section 130 operatively coupled to the combustion section 120 to produce work. For example, the turbine 128 may be connected to a shaft 132 such that rotation of the turbine 128 drives the compressor 108 to produce the HP air 112. Alternatively or additionally, the shaft 132 may connect the turbine 128 to another load, such as a generator 134 for generating electricity. Exhaust gases 136 from the turbine 128 flow through an exhaust section 138 that connects the turbine 128 to a downstream exhaust stack 140. The exhaust section 138 may include, for example, a heat recovery steam generator (not shown) to clean the exhaust gases 136 and extract additional heat before they are released to the environment. When two or more combustors 100 are used, they may be spaced circumferentially about a turbine inlet 142 of the turbine 128.

[0038] In one embodiment, the GT system 90 includes an engine model commercially available from GE Vernoa (Cambridge, Massachusetts, USA). The present disclosure is not limited to any particular GT system and may be implemented with other engines, including, for example, GE Vernoa's HA, F, B, LM, GT, TM, and E-class engine models, as well as engine models from other manufacturers. The present disclosure is not limited to implementation with any particular turbomachine and may be applicable to steam turbines, jet engines, compressors, turbofans, etc.

[0039] The following describes a combustor 100 that may be used in the GT system 90. Figure 2 illustrates a cross-sectional side view of the combustor 100 disposed within the GT system 90. As described further herein, the combustor 100 may include one or more axial fuel stage (AFS) injectors 150 according to embodiments of the present disclosure.

[0040] 2, the combustor 100 is at least partially surrounded by an outer casing 152, such as a compressor discharge casing and / or a turbine casing. The interior of the outer casing 152 is in fluid communication with the compressor discharge 109 of the compressor 108 and provides the HP air source 154. That is, the HP air source 154 includes HP air 112 from the compressor discharge 109 of the compressor 108. The HP source 154 is in direct fluid communication with the compressor discharge 109 of the GT system 90. However, the HP air source 154 may be any source of HP air 112 that can be channeled to various openings or flow passages of the combustor 100 (i.e., within the AFS injectors 150) for component cooling and / or combustion.

[0041] As shown in FIG. 2 , the combustor 100 for the GT system 90 includes a combustor body 160. The combustor body 160 may be manufactured using any now known or later developed technology. For example, the combustor body 160 may be manufactured using additive manufacturing. The combustor body 160 may include a combustion liner 164, which may include, for example, a cylindrical portion 166 and a tapered transition portion 168. The combustion liner 164 may have an axis A, the direction of which may vary slightly depending on the axial position of the curved combustion liner 164. The tapered transition portion 168 is at the aft end (to the right in FIG. 2 ) of the cylindrical portion 166. As will be apparent to one skilled in the art, the tapered transition portion 168 transitions the hot gas path (HGP) from a circular cross-section of the cylindrical portion 166 of the liner to an arcuate cross-section that mates with the turbine inlet 142 of the turbine 128. The combustor 100 may further include an aft frame 170 at the aft end (to the right in FIG. 2) of the tapered transition section 168 .

[0042] Combustion liner 164 contains and channels combustion gases 122 to turbine section 130 ( FIG. 1 ). More specifically, combustion liner 164 defines a combustion chamber 172 in the hot gas path (HGP) within which combustion occurs. Combustion liner 164 may have a tapered transition section 168 that is separate from cylindrical section 166, as in many conventional combustion systems. Alternatively, as shown in FIG. 2 , combustion liner 164 may have a one-piece (or “unibody”) construction, in which cylindrical section 166 and tapered transition section 168 are integrated with one another as part of a single, additively manufactured part. Thus, all references herein to combustion liner 164 encompass both conventional combustion systems having separate cylindrical sections and tapered transition sections, as well as combustion systems having unibody liners.

[0043] The combustor body 160 also includes an airflow passage 174 defined at least in part by the cylindrical portion 166 of the combustion liner 164. As described herein, the airflow passage 174 is configured to deliver air (e.g., HP air 112A from the HP air source 154) to a head-end fuel nozzle assembly 176 (hereinafter simply referred to as the “head-end assembly 176”) of the combustor 100 at the forward end (left end in FIG. 2 ) of the combustion liner 164. That is, the airflow passage 174 is sized, shaped, and / or configured to deliver air (e.g., HP air 112A from the HP air source 154) to the head-end assembly 176 of the combustor 100. The airflow passage 174 may be defined entirely by the cylindrical portion 166, or the airflow passage 174 may be provided between the cylindrical portion 166 and a flow sleeve 177 spaced along at least a portion of the outer surface of the cylindrical portion 166. The airflow path 174 has an open end 178, or one or more airflow openings, near the head end assembly 176 through which HP air 112A from the HP air source 154 enters. The HP air 112A from the HP air source 154 may be taken directly from the compressor discharge, i.e., without using any air other than for simultaneous convective cooling of the combustor body 160.

[0044] An annular partition 179, located between the cylindrical portion 166 and the flow sleeve 177, separates a forward portion of the airflow passage 174 from an aft portion of the airflow passage 174. The axial position of the annular partition 179 is generally aligned with the cap assembly 198, described below, and the forward portion of the airflow passage 174 is radially outward of the head-end assembly 176 (rather than the combustion chamber 172) and does not require significant cooling. Aft of the annular partition 179, the flow sleeve 177 may include a plurality of impingement holes 192 (shown in the outer sleeve 190) to allow the HP air 112B to enter the airflow passage 174. After passing through the impingement holes 192, the HP air 112B undergoes a pressure drop, becoming LP air 182 and flowing through the airflow passage 174 to and / or into one or more AFS injectors 150, as further described herein.

[0045] The head end assembly 176 generally includes one or more axially extending fuel nozzles 194 extending downstream from the end cover 196 and a cap assembly 198 extending radially and axially within the outer casing 152 downstream from the end cover 196 and defining a forward boundary of the combustion chamber 172. The head end assembly 176 may include any now known or later developed axially extending fuel nozzles 194 for channeling the first fuel 114A from the axially extending fuel nozzles 194 to the primary combustion zone 202. In certain embodiments, the axially extending fuel nozzles 194 of the head end assembly 176 extend at least partially through the cap assembly 198 and deliver a combustible mixture of the fuel 114A and HP air 112A to the primary combustion zone 202.

[0046] The combustor body 160 also includes axial fuel stage (AFS) injector openings or seats 180 facing the combustion liner 164 downstream of the head-end assembly 176. The openings or seats 180 extend through the wall of the combustion liner 164. One or more AFS injector openings or seats 180 (hereinafter referred to as “openings 180”) may be provided, in which AFS injectors 150 are mounted and configured to receive HP air 112B from the HP air source 154 (although other air flows are possible as described herein). Each AFS injector opening 180 may include any necessary structure (e.g., threaded fasteners, bolt holes, welded areas, etc.) to which the AFS injector 150 may be mounted. As shown, the combustor 100 and combustor body 160 may include multiple circumferentially spaced AFS injector openings 180 and corresponding AFS injectors 150. Any number of AFS injectors 150 may be used.

[0047] As described below, in some embodiments, the AFS injector 150 may be configured to receive low-pressure (LP) air 182 from a low-pressure (LP) air source 184, such as a cooling passage, and direct the LP air 182 along with fuel 114B to the combustion liner 164. The fuel 114B may be supplied from a fuel source 116 using any form of fuel line 188. The fuels 114A, 114B may be any currently known or future developed combustor 100 fuel, such as, but not limited to, fuel oil, natural gas, hydrogen, and / or blends thereof. The fuels 114A, 114B may be the same or different.

[0048] In several embodiments, LP air 182 can be supplied to AFS injectors 150 from LP air source 184 in a variety of ways. In certain embodiments, LP air 182 originates from HP air source 154 but is used for cooling before being used by AFS injectors 150. In one example, combustor body 160 further includes cooling passages 186 defined at least in part by tapered transition section 168. In this configuration, one or more cooling passages 186 constitute LP air source 184. One or more cooling passages 186 may be in fluid communication with other cooling passages (not shown) in combustor 100 (e.g., in aft frame 170). In any event, LP air 182 from LP air source 184 may be used to cool one or more high-temperature components of combustor 100. More specifically, LP air 182 from LP air source 184 is removed from compressor discharge 109 and then passes through cooling passage 186 (defined at least in part by tapered transition 168).

[0049] In one example, the cooling passages 186 may be defined by a flow sleeve 190 or within the tapered transition section 168. If desired, impingement cooling holes 192 may be provided in the flow sleeve 190 surrounding the tapered transition section 168 so that the HP air 112 from the HP air source 154 flows into the LP air 182. In this regard, the LP air source 184 includes one or more cooling passages 186 defined along at least a portion of the combustion liner 164 (e.g., the tapered transition section 168) as well as upstream cooling passages of other high temperature components of the combustor 100. Furthermore, the one or more cooling passages 186 may be downstream of an impingement cooling member (e.g., the outer sleeve portion 168 with the impingement cooling holes 192 or the sleeve 190 around the portion 190 with the holes 192) that is in direct fluid communication with the compressor discharge section 109 (i.e., the HP air source 154) of the GT system 90. The high-temperature components may include any components of the combustor 100 that require cooling, and the LP air 182 may be directed into the cooling passages 186 as desired. That is, one or more cooling passages 186 may be defined in or along (another) high-temperature component of the combustor 100 other than the tapered transition 168 (e.g., the aft frame 170). The LP air source 184 may also be considered to be in fluid communication with the cooling passages 186 defined along at least a portion of the combustion liner 164 of the combustor 100. In either case, the one or more cooling passages 186 are between the AFS injectors 150 and the HP air source 154, and in some embodiments, the cooling passages 186 are configured to deliver the LP air 182 from the LP air source 184 to the AFS injectors 150. Because the LP air 182 from the LP air source 184 is used to cool components of the combustor 100, it is also referred to herein as “post-cooling” or “post-impingement air.”

[0050] As described above, the combustor 100 includes one or more axially staged fuel (AFS) injectors 150 facing the combustor body 160 (i.e., the combustion liner 164). As described above, the AFS injectors 150 may include multiple AFS injectors 150 spaced circumferentially around the combustor body 160. Each AFS injector 150 extends radially toward an opening 180 in the combustion liner 164 downstream of the head-end assembly 176 (i.e., downstream of the axially extending fuel nozzles 194). As described below, the AFS injectors 150 are configured to receive HP air 112B and second fuel 114B from the HP air source 154 for combustion in the secondary combustion zone 204 downstream of the primary combustion zone 202. In certain embodiments, the AFS injectors 150 may optionally draw LP air 182 from the LP air source 184. In this case, LP air 182 from LP air source 184 may be routed to AFS injector 150, for example, via cooling passage 186, and combined with HP air 112B and second fuel 114B for combustion in a secondary combustion zone 204 downstream of the primary combustion zone 202.

[0051] 3-6 show various views of an AFS injector 150 according to an embodiment of the present disclosure. FIG. 3 shows a perspective partial cross-sectional view of the AFS injector 150. FIG. 4 shows a cross-sectional view taken along line 4-4 of FIG. 3. FIG. 5 shows a cross-sectional view taken along line 5-5 of FIG. 3. FIG. 6 shows a cross-sectional view taken along line 6-6 of FIG. 3. The AFS injector 150 includes a mixing element 210 and a high-pressure (HP) air-fuel injection element 212. The mixing element 210 and the HP air-fuel injection element 212 are coupled together to form the AFS injector 150. More specifically, as shown in FIGS. 3-6 , the mixing element 210 and the HP air-fuel injection element 212 may each include one or more mounting elements 213 configured to receive fasteners 215 (e.g., bolts, welds, or other fasteners) that couple the mixing element 210 and the HP air-fuel injection element 212 to the combustor body 160 ( FIG. 2 ), such as an AFS injector mount 274 coupled to the outer sleeve 190. Alternatively, the mixing element 210 and the HP air-fuel injection element 212 may be formed as a single, integral member, for example, by additive manufacturing. Each AFS injector 150 is aligned with and positioned within a respective opening 180 in the combustion liner 164. The HP air-fuel injection element 212 may hereinafter be referred to simply as the “injection element 212.”

[0052] As shown in FIGS. 3-6 , the mixing element 210 includes a mixing chamber 214 defined therein. The mixing chamber 214 includes an inlet 216 and an outlet 218. The inlet 216 is radially inward of the HP air-fuel injection element 212, and the outlet 218 is configured to be in fluid communication with the combustion liner 164 of the combustor 100 ( FIG. 2 ). The outlet 218 may be defined by the mixing element 210 having any cross-sectional shape. In one example, the outlet 218 has an axially elongated slot cross-sectional shape. In either case, the mixing element 210 has its outlet 218 positioned and secured within the opening 180 of the combustion liner 164.

[0053] The mixing chamber 214 may take a variety of forms. More specifically, as shown in FIGS. 3-6, the mixing chamber 214 may be axially elongated or may comprise a generally elongated chamber having elongated opposing walls 220, 222 and opposing ends 226. The mixing chamber 214 is referred to as "axially elongated" because its longitudinal length may be generally aligned with the axis A of the combustion liner 164. As shown in FIG. 4, the opposing ends 226 may be rounded as they transition to the respective opposing walls 220, 222. That is, the two opposing side walls 220, 222 and the opposing ends 226 join at their longitudinal ends to define an elliptical cross-sectional shape. Although not shown, the mixing chamber 214 may have some curvature and / or narrowing from the inlet 216 to the outlet 218, if desired.

[0054] 3, 5, and 6, the mixing chamber 214 may extend radially relative to the circumference C of the combustion liner 164 (from right to left on the page of FIGS. 5-6). Thus, the mixing chamber 214 extends radially (i.e., along a particular radial direction R) relative to the axis A of the combustion liner 164. The dimensions of the mixing chamber 214 are user-determined based on the characteristics of the fuel 114B, HP air 112B, LP air 182, and / or combustion liner 164, among many other considerations. As shown in FIG. 4, the length LM of the mixing chamber 214 from the inlet 216 to the outlet 218 is user-determined. Dimensions of all components of the mixing element 210 (and HP air-fuel injection element 212) of the AFS injector 150 may be customized to produce the desired (final) air-fuel mixture 276.

[0055] With continued reference to FIGS. 3-6 , the HP air-fuel injection member 212 will now be described. The HP air-fuel injection member 212 may also be referred to as a "top hat." The HP air-fuel injection member 212 includes one or more rows 230 of HP air-fuel injectors 232 for directing an (initial) air-fuel mixture 236 into the mixing chamber 214. FIGS. 3-6 show three rows 230A-C of the HP air-fuel injectors 232. More specifically, the one or more rows 230 of HP air-fuel injectors 232 include a first row 230A of HP air-fuel injectors 232, a second row 230B of HP air-fuel injectors 232, and a third row 230C of HP air-fuel injectors 232 between the first row 230A of HP air-fuel injectors 232 and the second row 230B of HP air-fuel injectors 232. Figure 7 shows a perspective, partial cross-sectional view of an AFS injector having two rows 230A-B of HP air-fuel injectors 232. That is, the one or more rows 230 of HP air-fuel injectors 232 include a first row 230A of HP air-fuel injectors 232 and a second row 230B of HP air-fuel injectors 232. Figure 8 shows a perspective, partial cross-sectional view of an AFS injector 150 having one row 230 of HP air-fuel injectors 232.

[0056] 4-6, the HP air-fuel injection element 212 may optionally include a filter element 238 upstream of the set of HP air-fuel injectors 232. For clarity, the filter element 238 is not shown in FIG. 3. The filter element 238 may include any now known or later developed filter structure capable of preventing unwanted contaminants from entering the AFS injector 150 from the HP air source 154.

[0057] FIG. 9 shows a schematic perspective view of an HP air-fuel injector 232 according to an embodiment of the present disclosure, and FIG. 10 shows a schematic cross-sectional view. Note that the schematics of the HP air-fuel injectors 232 in FIGS. 9 and 10 are referred to as schematic views because the injector is typically fabricated with the remainder of the injection member 212, typically using additive manufacturing, and is not a separate entity as shown. Each HP air-fuel injector 232 includes two opposing sidewalls 240, 242 and an intermediate wall 244 extending longitudinally between the two opposing sidewalls 240, 242. The intermediate wall 244 and each opposing sidewall 240, 242 define elongated high-pressure (HP) air jets 246A, 246B therebetween. The HP air jets 246A, 246B can have any desired cross-sectional shape. In one non-limiting example, each HP air jet 246A, 246B has an elongated cross-sectional shape, such as a rounded slot, an ellipse, or an oval. The HP air jets 246A, 246B are longer than they are wide and typically have relatively narrow openings. The axial spacing of the HP air jets 246A, 246B (and the HP air-fuel injector 232) relative to the axis A of the combustion liner 164 is user-determinable to produce a desired air-fuel mixture 236. In one embodiment, as shown in FIG. 9 , the two opposing side walls 240, 242 and the intermediate wall 244 are joined at their longitudinal ends, and the two opposing side walls 240, 242 collectively have an elliptical cross-sectional shape, i.e., a racetrack shape. In another example (not shown), each HP air jet 246A, 246B may have a circular cross-sectional shape. (Note that for clarity, only one HP air fuel injector 232 is shown in detail in FIGS. 3-4.)

[0058] Each HP air-fuel injector 232 also includes one or more fuel injectors 248 defined at a radially inner end (tip) 250 ( FIG. 10 ) of the intermediate wall 244 and in fluid communication with a fuel plenum 252 defined within the intermediate wall 244, among other areas. The radially inner end 250 of the intermediate wall 244 is also the aft end with respect to the flow of HP air 112B in the HP air-fuel injector 232. In some cases, the intermediate wall 244 has a teardrop-shaped cross-sectional shape (or a symmetrical airfoil) with a bulbous end 249 and a narrow tip (radially inner end) 250, and the one or more fuel injectors 248 are at the tip 250. The intermediate wall 244 may have other cross-sectional shapes. (Note that the fuel plenum 252 is not shown in FIG. 6 , and the fuel injectors 248 are not shown in FIGS. 6 and 9 .) 9, the fuel plenum 252 defined in the intermediate wall 244 may extend from one end 253 of the intermediate wall 244 to an opposite end 255 of the intermediate wall 244. However, in other cases, the fuel plenum 252 may extend only a portion of the length of the intermediate wall 244; for example, the intermediate wall 244 may be open at one end and closed at the other. Alternatively, the fuel plenum 252 may be configured to supply fuel 114B from the fuel source 116 to each of the fuel injectors 248.

[0059] The fuel plenum 252 may extend through the HP air-fuel injection member 212 in any manner necessary to supply fuel 114B to the desired HP air-fuel injectors 232. More specifically, the fuel plenum 252 may extend around each HP air-fuel injector 232 and into the mid-wall 244 of each injector. The AFS injectors 150, and more specifically, the HP air-fuel injection members 212, may include inlet ports 254 ( FIGS. 3-4 ) in fluid communication with the fuel plenum 252 and are configured to receive fuel 114B from the fuel source 116 ( FIGS. 1-2 ). The inlet ports 254 of each AFS injector 150 may be fluidly coupled to the fuel source 116 by, for example, the fuel line 188 ( FIG. 2 ) and, optionally, a distribution plenum (not shown) around the combustion liner 164. In either case, the fuel plenum 252 is configured to supply fuel 114B from the fuel source 116 to the fuel injectors 248. As discussed above, the fuel 114B can be any now known or future developed combustor 100 fuel, such as, but not limited to, fuel oil or natural gas. A technical advantage of the AFS injectors 150 is that the fuel 114B can also include highly reactive fuels, such as hydrogen. The fuel 114B may also include a blend of fuels, such as natural gas and hydrogen.

[0060] The HP air-fuel injectors 232 and their rows 230 can take a variety of forms. To further illustrate the options, Figure 11 shows an enlarged perspective cross-sectional view of the HP air-fuel injection member 212 according to the embodiment of Figures 3-6, and Figure 12 shows an enlarged perspective cross-sectional view of the HP air-fuel injection member 212 according to another embodiment. Additionally, Figure 13 shows a bottom view of the HP air-fuel injection member 212 according to an embodiment of the present disclosure, and Figure 14 shows an enlarged bottom view of a portion of the HP air-fuel injection member 212 according to an embodiment of the present disclosure.

[0061] In the examples shown in Figures 3-6 and 11-14, when the HP air-fuel injection member 212 includes two or more rows (e.g., 230A-B or 230A-C) of HP air-fuel injectors 232, it may further include a tapered deflector wall 234 downstream of and between the outlets of adjacent HP air nozzles 246 of the HP air-fuel injectors 232 of the first row 230A and the HP air-fuel injectors 232 of the second row 230B. 13 and 14 , when three rows 230A-C are provided, the HP air-fuel injectors 232 of the third row 230C may be axially offset from the HP air-fuel injectors 232 of the first row 230A and the second row 230B, and the tapered baffle wall 234 may be downstream of and between the outlets of the adjacent HP air jets 246 of the HP air-fuel injectors 232 of the first row 230A and the second row 230B (i.e., closer to the mixing chamber 214). In either case, the tapered baffle wall 234 acts to direct the air-fuel mixture 236 exiting the HP air-fuel injectors 232 toward the center of the mixing chamber 214. The HP air-fuel injection member 212 may optionally include diverging openings 256 (FIG. 4) downstream of each HP air-fuel injector 232 to promote mixing of the air and fuel. The openings 256 may have other shapes (e.g., curved parallel walls, etc.) as desired.

[0062] The rows of HP air-fuel injectors 232 may be angled to promote mixing of the fuel 114B with the HP air 112B (and, optionally, the LP air 182) to form the air-fuel mixture 236. In this regard, the HP air-fuel injectors 232 of the third row 230C may direct the air-fuel mixture 236 exiting therefrom in a direction parallel to the mixing chamber 214. In contrast, as shown in FIG. 5 , the HP air-fuel injectors 232 of the first row 230A and the second row 230B may direct the air-fuel mixture 236 exiting therefrom into the mixing chamber 214 at an acute angle α1 or α2, respectively. Note that the angles α1 and α2 of the rows 230A and 230B may be the same or different. In any case, the row 230 of HP air-fuel injectors 232 is intended to direct the air-fuel mixture 236 exiting therefrom toward the center of the mixing chamber 214. Further, as shown in Figures 3-6, when supplying LP air 182, the row 230 of HP air-fuel injectors 232 is intended to direct the air-fuel mixture 236 exiting therefrom such that the LP air 182 is entrained in the air-fuel mixture 236.

[0063] The HP air-fuel injectors 232 may have any cross-sectional area necessary to achieve the desired air-air-fuel mixture 236. For example, as shown in FIGS. 3, 4, 6, and 11, if the HP air jets 246 are elongated, the HP air jets 246A-B of the HP air-fuel injectors 232 in the first, second, and third rows 230A-C may have the same length L (FIG. 11). In other embodiments, the HP air jets 246 may have different lengths in different rows 230. For example, as shown in FIG. 12, the HP air jets 246A, 246B of the HP air-fuel injectors 232 in the third row 230C may be longer than the HP air jets 246A, 246B of the HP air-fuel injectors 232 in the first and second rows 230A, 230B. That is, L2 > L1, as shown in FIG. 12. In this way, many air-fuel mixtures 236 can be directed parallel to the mixing chamber 214. If the HP air jets 246 have other cross-sectional shapes, the cross-sectional area of ​​each jet in a given row may be similarly varied.

[0064] The fuel injectors 248 in the midwall 244 of each HP air fuel injector 232 can take a variety of forms. As shown in FIGS. 10, 13, and 14, the fuel injector 248 may include a single opening, for example, in the form of a slot. FIG. 15 shows a bottom view of an HP air fuel injector 232 with a fuel injector 248 including multiple fuel injectors 248, such as, but not limited to, a series of circular or slotted openings. When circular fuel injectors 248 are used, the fuel injectors 248 may be cylindrical openings or may have a narrowing nozzle cross-section to distribute the fuel 114B. In either case, the fuel injectors 248 can introduce the fuel 114B into the HP air 112B in a desired direction. For example, a particular fuel injector 248 in the intermediate wall 244 may direct fuel 114B toward HP air jets 246A, while another fuel injector 248 in the intermediate wall 244 may direct fuel 114B toward HP air jets 246B. In any case, the type, number, orientation, spacing, and size of the fuel injectors 248 may be selected depending on, for example, a variety of characteristics of the combustor 100, the HP air 112B, the LP air 182, and / or the fuel 114B. For example, with respect to the fuel 114B, characteristics may include, but are not limited to, the type of liquid or gas, the level of reactivity, viscosity, desired flow rate or volume, pressure, temperature, etc. Similar characteristics of the air 112B, 182 may also be considered. In any case, other configurations of the fuel injectors 248 are possible.

[0065] 13-14 , in certain embodiments using LP air 182, recesses 260 may be defined in a radially inner wall 262 of the HP air-fuel injection member 212 between adjacent HP air-fuel injectors 232 in each of the first and second rows 230A, 230B of HP air-fuel injectors 232. The recesses 260 provide space to direct the LP air 182 toward the mixing chamber 214 and reduce pressure loss.

[0066] FIG. 16 shows a perspective, partial cross-sectional view of an AFS injector 150 according to another embodiment of the present disclosure, and FIG. 17 shows a cross-sectional view taken along line 17-17 of FIG. 16 . In these embodiments, the injection member 212 may further include one or more rows 266 of HP air ejection slots 268 circumferentially spaced apart from one or more rows of HP air-fuel injectors 232 to direct a separate flow of HP air from the HP air source 154 toward the inlet of the mixing chamber 214. In this case, the use of LP air 182 can be eliminated by not providing fluid communication between the AFS injector 150 and the LP air source 184. FIGS. 16-17 also illustrate that LP air 182 is not used as part of the final air-fuel mixture 276 delivered by the AFS injector 150. In this configuration, the mixing member 210 and / or injection member 212 may include a wall 270 that prevents the LP air 182 from entering the mixing chamber 214. More specifically, the wall 270 defines a sealed chamber 272 between the mixing member 210 and the injection member 212 to prevent additional (ie, LP) air from entering the air-fuel mixture 236 exiting the HP air-fuel injector 232 .

[0067] In operation, as shown in Figures 10, 16, and 17, each elongated HP air jet 246 is configured to direct a flow of HP air 112B from the HP air source 154 toward the inlet 216 of the mixing chamber 214 in the same direction as the flow of fuel 114B from one or more fuel injectors 248, without utilizing LP air 182. Because the HP air 112B and fuel 114B are directed in the same direction by the HP air-fuel injectors 232, the fuel 114B does not need to penetrate the flow of HP air 112B, spin into the air stream, or otherwise mix with the air stream, thereby eliminating low-velocity and / or fuel-rich regions that could support a flame. The HP air-fuel injectors 232 produce a mixture of fuel 114B and HP air 112B without the problems described above.

[0068] In operation, as shown in Figures 3-6 and 10, the flow of HP air 112B may take in LP air 182 from LP air source 184 and direct the LP air 182 along with the HP air 112B to inlet 216 of mixing chamber 214, i.e., enter mixing chamber 214 along with fuel 114B as part of air-fuel mixture 236. Thus, air-fuel mixture 236 entering mixing chamber 214 (and air-fuel mixture 276 exiting mixing chamber 214) includes HP air 112B and fuel 114B, and may optionally also include LP air 182. Note that even when mixed with LP air 182, air-fuel mixture 236 (and 276) maintains a relatively high pressure, although not as high as HP air 112B from HP air source 154 (e.g., compressor discharge 109 (Figure 2)), and thus can be referred to as high pressure. Additional mixing of the air 112B, 182 and fuel 114B occurs within the mixing chamber 214 before the air-fuel mixture 276 exits the AFS injector 150 and enters the combustion liner 164 where it is combusted in the secondary combustion zone 204.

[0069] The AFS injector 150 (i.e., the mixing element 210 and the injection element 212) can be made of any combustion- and oxidation-resistant material now known or later developed. The material can be a metal, either a pure metal or an alloy. The AFS injector 150 can include metals commonly used in turbine components, such as turbine blades or nozzles, that have higher temperature and oxidation resistance than materials commonly used in combustion hardware. In this case, the material may comprise a non-reactive metal powder, such as, but not limited to, a non-explosive or non-conductive powder, such as a cobalt-chromium-molybdenum (CoCrMo) alloy, stainless steel, an austenitic nickel-chromium-based alloy, such as nickel-chromium-molybdenum-niobium (NiCrMoNb) alloy (e.g., Inconel 625 or Inconel 718), nickel-chromium-iron-molybdenum (NiCrFeMo) alloy (e.g., Hastelloy® X available from Haynes International), nickel-chromium-cobalt-molybdenum (NiCrCoMo) alloy (e.g., Haynes 233 or Haynes 282 available from Haynes International), or nickel-chromium-cobalt-titanium (NiCrCoTi) alloy (e.g., GTD262 developed by General Electric). Other possibilities include, for example, Rene 108, CM247, MarM247, and other precipitation-hardened (PH) nickel-based alloys.

[0070] In some embodiments, the AFS injector 150 (i.e., the mixing element 210 and / or the injection element 212) may be additively manufactured using any now known or later developed technology capable of forming a unitary body. As a result, as shown in FIG. 18 , the mixing element 210 and / or the injection element 212 includes multiple parallel sintered metal layers 280. FIG. 19 shows a schematic / block diagram of an exemplary computerized metal powder additive manufacturing system 310 (hereinafter “AM system 310”) for producing the AFS injector 150 (i.e., the mixing element 210 and / or the injection element 212) (only one layer of which is shown). While this disclosure describes building the mixing element 210 and / or the injection element 212 using multiple melt beam sources 312, 314, 316, 318, it will be apparent that the teachings of this disclosure are equally applicable to building the mixing element 210 and / or the injection element 212 using any number of melt beam sources. In this example, the AM system 310 is configured for direct metal laser melting (DMLM). The general teachings of this disclosure are equally applicable to other forms of metal powder additive manufacturing, such as selective laser melting (SLM), and possibly other forms of additive manufacturing (i.e., other than metal powder applications). While the layers of mixing element 210 and / or injection element 212 on the build platform 320 are shown as circular elements in FIG. 19, the additive manufacturing process can be readily adapted to produce any shape on the build platform 320.

[0071] The AM system 310 generally includes an additive manufacturing control system 330 ("control system") and an AM printer 332. As described below, the control system 330 executes a set of computer-executable instructions or code 334 for building the mixing element 210 and / or the jet element 212 using multiple melt beam sources 312, 314, 316, and 318. In the illustrated example, the four melt beam sources include four lasers. However, the teachings of this disclosure are applicable to any melt beam source, such as an electron beam, laser, etc. The control system 330 is shown implemented as computer program code on a computer 336. In this regard, the computer 336 includes a memory 338 and / or storage system 340, a processor unit (PU) 344, an input / output (I / O) interface 346, and a bus 348. Additionally, the illustrated computer 336 communicates with external I / O devices / resources 350.

[0072] Generally, processor unit (PU) 344 executes computer program code 334 stored in memory 338 and / or storage system 340. During execution of computer program code 334, processor unit (PU) 344 can read and / or write data to memory 338, storage system 340, I / O devices 350, and / or AM printer 332. Bus 348 provides a communication link between each component within computer 336, and I / O devices 350 may include any device (e.g., keyboard, pointing device, display, etc.) that allows a user to interact with computer 336. Computer 336 is merely representative of various possible combinations of hardware and software. For example, processor unit (PU) 344 may comprise a single processing unit or may be distributed across one or more processing units on one or more locations, e.g., a client and a server. Similarly, memory 338 and / or storage system 340 may reside in one or more physical locations. Memory 338 and / or storage system 340 may comprise any combination of various types of non-transitory computer-readable storage media, including magnetic media, optical media, random access memory (RAM), read-only memory (ROM), etc. Computer 336 may comprise any type of computing device, such as an industrial controller, a network server, a desktop computer, a laptop, a handheld device, etc.

[0073] As described above, the AM system 310, and particularly the control system 330, executes code 334 to create the mixed element 210 and / or the jet element 212. The code 334 may include, among other things, a set of computer-executable instructions 334S (also referred to herein as “code 334S”) for operating the AM printer 332 and a set of computer-executable instructions 334O (also referred to herein as “code 334O”) that define the mixed element 210 and / or the jet element 212 that are physically created by the AM printer 332. As described herein, the additive manufacturing process begins with a non-transitory computer-readable storage medium (e.g., memory 338, storage system 340, etc.) that stores the code 334. The set of computer-executable instructions 334S for operating the AM printer 332 may include any now known or later developed software code capable of operating the AM printer 332.

[0074] The set of computer-executable instructions 334O defining the mixing element 210 and / or the injection element 212 may include a precisely defined 3D model of the mixing element 210 and / or the injection element 212 and may be generated from any of a wide variety of well-known computer-aided design (CAD) software systems, such as AutoCAD™, TurboCAD™, DesignCAD3DMax, etc. In this regard, the code 334O may include any file format now known or later developed. Furthermore, the code 334O representing the mixing element 210 and / or the injection element 212 may be converted between different formats. For example, the code 334O may include a Standard Tessellation Language (STL) file created for 3D Systems' stereolithography CAD program, or an additive manufacturing file (AMF), an American Society of Mechanical Engineers (ASME) standard that is an XML-based format designed to allow any CAD software to describe the shape and configuration of any three-dimensional object to be manufactured by any AM printer. Code 334O representing the mixing element 210 and / or injection element 212 may also be converted to a set of data signals and transmitted, received as a set of data signals, converted to code as needed, stored, etc. In either case, code 334O is input to the AM system 310 and may originate from a part designer, an intellectual property (IP) provider, a design firm, the operator or owner of the AM system 310, or other source. In either case, control system 330 executes code 334S and code 334O to divide the mixing element 210 and / or injection element 212 into a series of thin slices that are sequentially deposited as layers of material in the AM printer 332.

[0075] The AM printer 332 may include an enclosed processing chamber 360 to provide a controlled atmosphere for printing the mixed element 210 and / or the ejection element 212. A build platform 320 on which the mixed element 210 and / or the ejection element 212 are built is disposed within the processing chamber 360. Multiple melt beam sources 312, 314, 316, 318 are configured to melt a layer of metal powder on the build platform 320 to produce the mixed element 210 and / or the ejection element 212. While four melt beam sources 312, 314, 316, 318 are illustrated, the teachings of the present disclosure are applicable to systems using any number of beam sources (e.g., 1, 2, 3, or 4 or more). As will be apparent to those skilled in the art, each melting beam source 312, 314, 316, and 318 may have a field that includes a non-overlapping field region capable of exclusively melting the metal powder, or may include one or more overlapping field regions capable of melting the metal powder with two or more beam sources. In this regard, each melting beam source 312, 314, 316, and 318 may generate a melting beam that fuses particles for each slice defined by code 3340. For example, FIG. 19 shows melting beam source 312 creating a layer of mixed element 210 and / or injection element 212 in one region using melting beam 362, and melting beam source 314 creating a layer of mixed element 210 and / or injection element 212 in another region using melting beam 362′.

[0076] Each melt beam source 312, 314, 316, 318 is calibrated by any now known or later developed method, i.e., each melt beam source 312, 314, 316, 318 provides individual positional corrections (not shown) to ensure its individual accuracy, thereby correlating the expected position of the laser or electron beam with its actual position relative to the build platform 320. In one embodiment, each of the multiple melt beam sources 312, 314, 316, 318 can produce a melt beam (e.g., 362, 362′) having the same cross-sectional dimensions (e.g., operational shape and dimensions), power, and scan speed.

[0077] 19 , an applicator (or recoater blade) 370 can create a thin layer of feedstock 372 spread as a blank canvas upon which each successive slice of the final metal mixed element 210 and / or jet element 212 is created. Various parts of the AM printer 332 can be moved to accommodate each new layer being added, for example, the build platform 320 can be lowered and / or the chamber 360 and / or applicator 370 can be raised after each layer. The process can use various feedstocks in the form of fine metal powders, and stocks of feedstock can be held in a powder reservoir 368 accessible to the applicator 370.

[0078] The process chamber 360 is filled with an inert gas, such as argon or nitrogen, and is controlled to minimize or completely eliminate oxygen. The control system 330 is configured to control the flow of a gas mixture 374 within the process chamber 360 from a source of inert gas 376. In this case, the control system 330 may control a pump 380 and / or a flow valve system 382 for the inert gas to control the content of the gas mixture 374. The flow valve system 382 may include one or more computer-controllable valves, flow sensors, temperature sensors, pressure sensors, etc., that can precisely control the flow of specific gases. The pump 380 can be provided with or without the valve system 382. If the pump 380 is omitted, the inert gas can simply enter a conduit or manifold prior to introduction into the process chamber 360. The source of the inert gas 376 can take the form of any conventional source for the materials contained therein, such as a tank, reservoir, or other source. Any sensors (not shown) necessary to measure the gas mixture 374 may be provided. The gas mixture 374 may be filtered using a filter 386 in a conventional manner.

[0079] During operation, a build platform 320 loaded with metal powder is provided within the process chamber 360, and a control system 330 controls the flow of a gas mixture 374 within the process chamber 360 from a source of inert gas 376. The control system 330 also controls the AM printer 332, particularly the applicator 370 and melt beam sources 312, 314, 316, and 318, to sequentially melt layers of metal powder on the build platform 320 to produce the mixed element 210 and / or jet element 212 according to embodiments of the present disclosure. Although a particular AM system 310 has been described herein, the teachings of the present disclosure are not limited to any particular additive manufacturing system or method.

[0080] Once the mixing element 210 and the injection element 212 are formed, they can be assembled with other portions of the combustor 100 to form the AFS injector 150, as shown in FIG. 2. For example, as shown in FIGS. 3-5, the mixing element 210 and / or the injection element 212 may be bolted to an AFS injector mount 274 (FIGS. 3-5) on the combustion liner 164. More specifically, as described above, the mixing element 210 and the HP air-fuel injection element 212 may each include one or more attachment elements 213 (e.g., bolts or welds) configured to receive fasteners 215 to couple the mixing element 210 and the HP air-fuel injection element 212 to the combustion liner 164 (i.e., the AFS injector mount 274 on the combustion liner 164) that defines the combustion chamber 172.

[0081] Embodiments of the present disclosure may also include a combustor 100 for the GT system 90. The combustor 100 includes a combustor body 160 that includes a combustion liner 164. The combustor 100 may include a plurality of AFS injectors 150 facing the combustion liner 164, as described herein. Returning to FIG. 2 , the combustor 100 generally terminates adjacent a stationary nozzle 284 of a first stage 282 of the turbine 128. The stationary nozzle 284 of the first stage 282 at least partially defines the turbine inlet 142 to the turbine 128. The combustor body 160 (i.e., the combustion liner 164) at least partially defines a hot gas path (HGP) for channeling combustion gases 122 from the primary combustion zone 202 and secondary combustion zone 204 to the turbine inlet 142 of the turbine 128 during operation of the GT system 90. The small size of the AFS injector 150 allows the AFS injector 150 to be mounted to a combustion liner 164 of a combustor body 160 (FIG. 2), which can be installed generally axially into the GT system 90 through a relatively small opening (not shown) in the compressor discharge casing (casing 152).

[0082] 1 , the GT system 90 may include a compressor section 110, a combustion section 120 operably coupled to the compressor section 110, and a turbine section 130 operably coupled to the combustion section 120. As described herein, the combustion section 120 includes one or more combustors 100 including a combustor body 160 including a combustion liner 164, and a head-end fuel nozzle assembly 176 at a forward end of the combustor body 160. The combustor 100 may include multiple AFS injectors 150 facing the combustor body 160 (i.e., the combustion liner 164 downstream of the head-end assembly 176), as described herein.

[0083] The present disclosure provides various technical and commercial advantages, examples of which are described below. As described herein, AFS injectors can accept high-pressure air and optionally low-pressure air (e.g., post-impingement cooling air) to reduce overall system pressure loss. AFS injectors can rapidly premix an air source with a highly reactive fuel, such as hydrogen, to achieve reduced emissions, such as nitrogen oxides (NOx), and achieve reasonable flameholding capabilities. AFS injectors enhance fuel-air mixing, minimize flow pressure loss, and prevent fuel from entering low-velocity airflow regions. Furthermore, because the AFS injectors have a relatively small radial height from top to bottom, they can be attached to the combustion liner of the combustor body, which can then be axially mounted to the GT system through a relatively small opening in the compressor discharge casing.

[0084] Approximate expressions used in this specification and claims are used to describe quantitative modifiers that can vary within acceptable limits without causing a change in the basic function to which the quantity relates. Thus, values ​​modified by terms such as "about," "approximately," and "substantially" are not limited to their exact numerical values. In at least some instances, approximate expressions correspond to the precision of the instrument used to measure the value. In some cases, approximate expressions correspond to the precision of the instrument used to measure the value. In this specification and claims, ranges of numerical limitations are combinable and / or interchangeable with each other. Such ranges specify and encompass all subranges within the range, unless otherwise clear from the context. The term "about" used in connection with a particular value in a range applies to both the upper and lower limits and may indicate ±10% of the stated numerical value, except where the precision of the instrument used to measure the value is dependent.

[0085] Corresponding structures, materials, acts, and equivalents of elements identified by functional descriptions in the following claims encompass any structures, materials, or acts that perform the function in combination with other elements specifically recited in the claims. The description of the present disclosure has been provided for purposes of illustration and description and is not intended to be exhaustive or limited to the disclosed form. Numerous modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The embodiments of the present disclosure have been selected and described to best explain the principles and practical applications of the present disclosure and to enable those skilled in the art to understand the disclosure regarding various embodiments and various modifications suitable for particular applications. [Explanation of symbols]

[0086] 90 Gas Turbine System 100 Combustor 108 Compressor 112 Compressed Air 114 Fuel 116 Fuel source 122 Combustion Gas 128 Turbine 150 Axial Fuel Stage Injector 154 High-pressure air source 164 Combustion Liner 172 Combustion chamber 176 Head End Fuel Nozzle Assembly 210 Mixing materials 212 High-pressure air fuel injection member 214 Mixing room 216 Mixing Room Entrance 218 Mixing chamber exit 232 High-Pressure Air Fuel Injector 234 Tapered Warped Wall 236 Air-Fuel Mixture 240,242 Opposite side walls 244 Intermediate Wall 246 High-pressure air nozzle 248 Fuel Injector

Claims

1. An axial fuel stage injector (150) for a combustor (100) of a gas turbine system (90), the axial fuel stage injector (150) comprising: a mixing element (210) having a mixing chamber (214) defined therein, the mixing chamber (214) having an inlet (216) and an outlet (218), the outlet (218) configured to be in fluid communication with a combustion chamber (172) of the combustor (100); a high-pressure air-fuel injection member (212) including one or more rows (230) of high-pressure air-fuel injectors (232) for directing an air-fuel mixture (236) into a mixing chamber (214); each high pressure air fuel injector (232) two opposing side walls (240, 242) and an intermediate wall (244) extending longitudinally between the two opposing side walls (240, 242), the intermediate wall (244) and each opposing side wall (240, 242) defining an elongated high-pressure air jet (246) therebetween; one or more fuel injectors (248) defined at a radially inner end of the intermediate wall (244); a fuel plenum (252) defined in the intermediate wall (244), the fuel plenum (252) configured to supply fuel (114B) from the fuel source (116) to each of the one or more fuel injectors (248); and each elongated high-pressure air jet (246) is configured to direct a flow of high-pressure air (112) from a high-pressure air source (154) toward an inlet (216) of a mixing chamber (214) in the same direction as a flow of fuel (114B) from one or more fuel injectors (248).

2. 2. The axial fuel stage injector of claim 1, wherein the one or more rows of high-pressure air fuel injectors include a first row of high-pressure air fuel injectors and a second row of high-pressure air fuel injectors, and the high-pressure air fuel injection member further includes a tapered deflector wall downstream of and between outlets of adjacent high-pressure air jets of the first row of high-pressure air fuel injectors and the second row of high-pressure air fuel injectors.

3. 2. The axial fuel stage injector of claim 1, wherein the one or more rows of high-pressure air fuel injectors include a first row of high-pressure air fuel injectors, a second row of high-pressure air fuel injectors, and a third row of high-pressure air fuel injectors between the first row of high-pressure air fuel injectors and the second row of high-pressure air fuel injectors.

4. 4. The axial fuel stage injector of claim 3, wherein the high pressure air-fuel injectors of the third row direct the air-fuel mixture in a direction parallel to the mixing chamber, and the high pressure air-fuel injectors of the first row and the second row direct the air-fuel mixture at an acute angle relative to a direction parallel to the mixing chamber.

5. 4. The axial fuel stage injector of claim 3, wherein the high pressure air jets of the high pressure air fuel injectors of the third row are longer in a transverse direction with respect to an axial direction of the axial fuel stage injector than the high pressure air jets of the high pressure air fuel injectors of the first row and the second row.

6. 4. The axial fuel stage injector of claim 3, wherein the high-pressure air jets of the first, second, and third rows of high-pressure air fuel injectors have the same length transversely to an axial direction of the axial fuel stage injector.

7. 4. The axial fuel stage injector of claim 3, wherein the high-pressure air fuel injectors of the third row are axially offset from the high-pressure air fuel injectors of the first row and the second row, and the high-pressure air fuel injection member further includes a tapered deflector wall downstream of and between outlets of adjacent high-pressure air jets of the first row and the second row.

8. 8. The axial fuel stage injector of claim 7, further comprising a recess defined in a radially inner wall of the high pressure air fuel injection member between a plurality of adjacent high pressure air fuel injectors of at least one of the first row of high pressure air fuel injectors and the second row of high pressure air fuel injectors.

9. 2. The axial fuel stage injector of claim 1, wherein the high-pressure air fuel injection member further comprises one or more rows of high-pressure air ejection slots circumferentially spaced from the one or more rows of high-pressure air fuel injectors for directing a separate flow of high-pressure air from the high-pressure air source toward the inlet of the mixing chamber.

10. The axial fuel stage injector (150) of any preceding claim, wherein the high pressure air fuel injection member (212) includes a diverging opening (256) downstream of each high pressure air fuel injector (232).

11. 2. The axial fuel stage injector of claim 1, wherein the two opposing side walls and the intermediate wall are joined at their longitudinal ends, and the two opposing side walls collectively have an elliptical cross-sectional shape.

12. 2. The axial fuel stage injector of claim 1, wherein the intermediate wall has a teardrop cross-sectional shape with a bulbous end and a tip, and wherein the one or more fuel injectors are at the tip.

13. The axial stage fuel injector (150) of any preceding claim, wherein the one or more fuel injectors (248) comprise a plurality of fuel injectors.

14. 2. The axial fuel stage injector of claim 1, wherein a fuel plenum defined in the intermediate wall extends from one end of the intermediate wall to an opposite end of the intermediate wall.

15. 2. The axial fuel stage injector of claim 1, wherein the flow of high pressure air also entrains low pressure air from a low pressure air source to direct the low pressure air along with the high pressure air to an inlet of the mixing chamber.

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