Axial fuel stage injector having plural mixing chambers, combustor including axial fuel stage injector, and gt system

Abstract

To provide an axial fuel stage (AFS) injector having plural mixing chambers, a combustor including the AFS injector and a gas turbine system.SOLUTION: An axial fuel stage (AFS) injector includes: a mixing member having plural mixing chambers in fluid communication with a combustion liner of a combustor; and a set of fuel injectors defined on a side wall of each mixing chamber. A fuel plenum is defined by the mixing member so as to deliver fuel to each set of the fuel injectors. Each set of HP air jets is configured to guide HP air from an HP air source, optionally suck LP air from a low pressure (LP) air source and guide the LP air together with the HP air to an inlet of each mixing chamber to which fuel is injected. The mixing chamber guides an air fuel mixture to the combustion liner for combustion in a secondary combustion zone thereof.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 having multiple mixing chambers, and combustor and gas turbine systems including AFS injectors. [Background technology]

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

[0003] All aspects, examples, and features described below can be combined in any technically possible manner.

[0004] One aspect of the disclosure is an axial fuel stage (AFS) injector for a combustor of a gas turbine (GT) system, the AFS injector including: a mixing element including a plurality of mixing chambers defined in the mixing element, each mixing chamber including an inlet and an outlet, each outlet configured to be in fluid communication with a combustion liner of the combustor; and a set of fuel injectors defined in a sidewall of each mixing chamber; an HP air injection element defining a set of high-pressure (HP) air jets spaced from the inlets of each mixing chamber; and a fuel plenum defined in the mixing element, the fuel plenum configured to deliver fuel from a fuel source to each set of fuel injectors, each set of HP air jets configured to direct HP air from the HP air source to the inlets of a respective mixing chamber where fuel is injected by the set of fuel injectors.

[0005] Another aspect of the present disclosure includes any of the preceding aspects, wherein at least one of the plurality of mixing chambers is inclined at an obtuse angle relative to the axis of the combustion liner.

[0006] Another aspect of the present disclosure includes any of the above aspects, wherein a set of HP air jets spaced from the inlet of each mixing chamber are configured to direct HP airflow into each mixing chamber at an angle identical to the angle of the respective mixing chamber.

[0007] Another aspect of the present disclosure includes any of the aforementioned aspects, wherein the fuel plenum is defined in the mixing element.

[0008] Another aspect of the present disclosure includes any of the aforementioned aspects, wherein each set of fuel injectors includes a first set of fuel injectors axially spaced from a second set of fuel injectors in each mixing chamber of the plurality of mixing chambers.

[0009] Another aspect of the present disclosure includes any of the aforementioned aspects, wherein the fuel plenum extends into an upstream wall of each of the plurality of mixing chambers.

[0010] Another aspect of the present disclosure includes any of the above aspects, wherein each set of fuel injectors is closer to the inlet than the outlet of each of the plurality of mixing chambers.

[0011] Another aspect of the present disclosure includes any of the preceding aspects, wherein each mixing chamber of the plurality of mixing chambers has a cylindrical shape.

[0012] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the plurality of mixing chambers is arranged in two rows of eight mixing chambers.

[0013] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein each set of HP air jets includes three HP air jets.

[0014] Another aspect of the present disclosure includes any of the preceding aspects, wherein each HP air jet has a circular cross-sectional shape.

[0015] Another aspect of the present disclosure includes any of the above aspects, wherein each of the plurality of mixing chambers is angled radially from the axis of the combustion liner.

[0016] Another aspect of the present disclosure includes any of the aforementioned aspects, wherein the mixing element and the HP air injection element each include a mounting element configured to receive a fastener to couple the mixing element and the HP air injection element to the combustion liner.

[0017] Another aspect of the present disclosure includes any of the aforementioned aspects, wherein each set of HP air jets is configured to draw low pressure (LP) air from a LP air source and direct the LP air along with the HP air to an inlet of a respective mixing chamber, the HP air source in direct fluid communication with a compressor discharge of the GT system, and the LP air source in fluid communication with a cooling passage defined along at least a portion of the combustion liner.

[0018] Another aspect of the present disclosure includes 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 directed toward the combustion liner, each AFS injector being a mixing element including a plurality of mixing chambers defined in the mixing element, each mixing chamber including an inlet and an outlet, each outlet being configured to be in fluid communication with the combustion liner of the combustor; and a set of fuel injectors defined in a sidewall of each mixing chamber; a high-pressure (HP) air injection element defining a set of HP air jets spaced from the inlet of each mixing chamber; and a fuel plenum defined in the mixing element, the fuel plenum configured to deliver fuel from a fuel source to each set of fuel injectors, each set of HP air jets configured to direct HP air from the HP air source to an inlet of a respective mixing chamber where fuel is injected by the set of fuel injectors.

[0019] Another aspect of the present disclosure includes any of the preceding aspects, wherein at least one of the plurality of mixing chambers is inclined at an obtuse angle relative to the axis of the combustion liner.

[0020] Another aspect of the present disclosure includes any of the above aspects, wherein a set of HP air jets spaced from the inlet of each mixing element are configured to direct HP airflow into each mixing chamber at an angle identical to the angle of the respective mixing chamber.

[0021] Another aspect of the present disclosure is a gas turbine (GT) system comprising: a compressor section; a combustion section operably coupled to the compressor section; and a turbine section operably coupled to the combustion section, the combustion section comprising at least one combustor 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 directed into the combustor body downstream of the head-end fuel nozzle assembly, each AFS injector being a mixing element, the mixing element defining a plurality of mixing chambers, each mixing chamber including an inlet and an outlet, each outlet being connected to a combustion liner of the combustor. the GT system includes at least one combustor including a mixing element including a plurality of mixing chambers configured to be in fluid communication with the inlet and a set of fuel injectors defined in a sidewall of each mixing chamber; a high-pressure (HP) air injection element defining a set of HP air jets spaced from the inlets of each mixing chamber; and a plurality of AFS injectors including a fuel plenum defined in the mixing element, the fuel plenum configured to deliver fuel from a fuel source to each set of fuel injectors, each set of HP air jets configured to direct HP air from the HP air source to the inlet of a respective mixing chamber where fuel is injected by the set of fuel injectors.

[0022] Another aspect of the present disclosure includes any of the aforementioned aspects, wherein each of the plurality of mixing chambers is inclined at an obtuse angle relative to the axis of the combustion liner, except for at least one mixing chamber at a downstream most axial location along the combustion liner.

[0023] Another aspect of the present disclosure includes any of the above aspects, wherein a set of HP air jets spaced from the inlet of each mixing chamber are configured to direct HP airflow into each mixing chamber at an angle identical to the angle of the respective mixing chamber.

[0024] Two or more aspects described in this disclosure, including those described in this summary section, may be combined to form an embodiment not specifically described herein, i.e., all embodiments described herein can 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, objects, and advantages will become apparent from the description and drawings, and from the claims.

[0026] These and other features of the present disclosure will be more readily understood from the following detailed description of the various aspects of the disclosure, taken in conjunction with the accompanying drawings which illustrate various embodiments of the present disclosure. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a functional block diagram of an exemplary gas turbine system that may be used with a combustor including an axial fuel stage (AFS) injector according to an embodiment 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 taken along line 4-4 of FIG. 3 according to an embodiment of the present disclosure. [Figure 5A] FIG. 5 is a cross-sectional view of an AFS injector taken along line 5-5 of FIG. 3 according to an embodiment of the present disclosure. [Figure 5B] FIG. 5 is a cross-sectional view of an AFS injector taken along line 5-5 of FIG. 3 according to another embodiment of the present disclosure. [Figure 6A] FIG. 1 is a top view of a mixing member of an AFS injector according to an embodiment of the present disclosure. [Figure 6B] FIG. 1 is a top view of a mixing member of an AFS injector according to an embodiment of the present disclosure. [Figure 6C]FIG. 1 is a top view of a mixing member of an AFS injector according to an embodiment of the present disclosure. [Figure 7A] FIG. 1 is a top view of a high-pressure air injection member of an AFS injector according to an embodiment of the present disclosure. [Figure 7B] FIG. 1 is a top view of a high-pressure air injection member of an AFS injector according to an embodiment of the present disclosure. [Figure 7C] FIG. 1 is a top view of a high-pressure air injection member of an AFS injector according to an embodiment of the present disclosure. [Figure 7D] FIG. 1 is a top view of a high-pressure air injection member of an AFS injector according to an embodiment of the present disclosure. [Figure 8] 8A is a cross-sectional view of a set of high-pressure air jets in a high-pressure air injection member taken along view line 8-8 of FIG. 7A according to an embodiment of the present disclosure. [Figure 9] 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 10] FIG. 1 is a schematic block diagram of an exemplary additive manufacturing system for additively manufacturing mixing members and / or high-pressure air injection members of an AFS injector according to embodiments of the present disclosure.

[0028] It should be noted that the drawings of the present disclosure are not necessarily to scale. The drawings are intended to depict only typical aspects of the disclosure and therefore should not be considered limiting of the scope of the disclosure. In the drawings, like reference numerals represent like elements between the drawings. DETAILED DESCRIPTION OF THE INVENTION

[0029] As an initial issue, a clear description of the state of the art requires the selection of specific terminology when referring to and describing related machine components within an exemplary application of a turbomachine combustor and axial fuel stage (AFS) injector. In doing so, common industry terminology is used where possible and consistent with its accepted meaning. Unless otherwise noted, such terminology should be given a broad interpretation consistent with the context of this application and the appended claims. Those skilled in the art will understand that in many cases, a particular component may be referred to using several different or overlapping terms. What may be described herein as being a single component may include, and be referred to in other contexts as consisting of multiple components. Alternatively, what may be described herein as comprising multiple components may be referred to elsewhere as a single component.

[0030] Additionally, several descriptive terms may be used periodically herein, and it will prove useful to define these terms at the beginning of this section. These terms and their definitions are as follows, unless otherwise stated: As used herein, "downstream" and "upstream" are terms that indicate a direction relative to the flow of a fluid, such as a working fluid through a combustor of a turbomachine, or, for example, the flow of air through a combustor or AFS injector, or a coolant through one of the component systems of a turbomachine. The term "downstream" corresponds to the direction of fluid flow, and the term "upstream" refers to the direction opposite to the flow. The terms "forward" and "aft" refer to directions, unless otherwise specified, with "forward" referring to the front or compressor end of the turbomachine or combustor and "aft" referring to the aft or turbine end of the turbomachine or combustor.

[0031] The term “axial” refers to movement or position parallel to an axis, e.g., the axis of a combustor, the mixing chamber of an AFS injector, or a turbomachine. The term “radial” refers to movement or position perpendicular to an axis, e.g., the axis of a combustor or turbomachine. In such cases, if a first component is located closer to the axis than a second component, the first component may be referred to herein as being “radially inward” or “inward” of the second component. Conversely, if a first component is located farther from the axis than a second component, the first component may be referred to herein as being “radially outward” or “outward” of the second component. Finally, the term “circumferential” refers to movement or position around an axis, e.g., the circumferential inner surface of a combustor body or the circumferential interior of a casing extending around the combustor. As noted above, it will be understood that, depending on the context, such terms may be applied with respect to the axis of a combustor or the axis of a turbomachine.

[0032] Additionally, certain descriptive terms may be used periodically herein, as described below: The terms "first," "second," and "third" may be used interchangeably to distinguish one component from another, and are not intended to denote the location or importance of the individual components.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly dictates otherwise. It will be further understood that the terms "comprise" and / or "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or sets thereof. "Optional" or "optionally" means that a subsequently stated event may or may not occur, or that a subsequently stated feature may or may not be present, and that the description includes instances in which the event occurs or the feature is present as well as instances in which the event does not occur or the feature is not present.

[0034] When an element or layer is referred to as "on," "engaged," "connected," "coupled," or "attached" to another element or layer, it may be directly on, engaged, connected, coupled, or attached to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly engaged," "directly connected," or "directly coupled" to another element or layer, there are no intervening elements or layers. Other words used to describe relationships between elements should be interpreted similarly (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The verb forms of "couple" and "attach" may be used interchangeably herein.

[0035] An embodiment of the present disclosure provides an axial fuel stage (AFS) injector for a combustor, a combustor including the AFS injector, and a gas turbine (GT) system including the AFS injector. The AFS injector includes a mixing element including multiple mixing chambers in fluid communication with a combustion liner of the combustor and a set of fuel injectors defined in a sidewall of each mixing chamber. A high-pressure (HP) air injection element defines a set of HP air jets spaced apart from the inlet of each mixing chamber. A fuel plenum is defined in the mixing element to deliver fuel from a fuel source to each set of fuel injectors. Each set of HP air jets is configured to direct HP air from an HP air source and, optionally, draw LP air from a low-pressure (LP) air source, and direct the LP air along with the HP air to the inlet of the respective mixing chamber where the fuel is injected. The mixing chambers direct the air-fuel mixture into the combustion liner for combustion in its secondary combustion zone. The AFS injector can be additively manufactured to include multiple parallel sintered metal layers.

[0036] In some embodiments, the AFS injector mixes two air sources, one high-pressure air from the compressor discharge, for example, and the other low-pressure air, for example, post-impingement cooling air or other air at a lower pressure than the high-pressure air, reducing pressure losses throughout the system and using the air more efficiently within the combustor. The AFS injector can rapidly premix the two air sources with a highly reactive fuel, for example, hydrogen, to achieve, for example, low nitrous oxide (NOx) emissions and acceptable flame-holding capabilities.

[0037] In each embodiment, the AFS injectors improve fuel-air mixing, reduce flow pressure loss, and prevent fuel from entering any low-velocity airflow zones. Additionally, the AFS injectors are packaged in a relatively small geometry, allowing them to be assembled onto the combustion liner of the combustor body, which is installed into the GT system through a relatively small opening in the compressor discharge casing.

[0038] 1 illustrates a functional block diagram of an exemplary gas turbine (GT) system 90 that may incorporate various embodiments of a combustor 100 and an axial fuel stage (AFS) injector 150 of the present disclosure. As shown, the GT system 90 generally includes an inlet section 102 that may include a series of filters, cooling coils, water separators, and / or other devices for cleaning and otherwise conditioning a working fluid (e.g., air) 106 entering the GT system 90. The working fluid 106, i.e., air, flows to a compressor 108 in a compressor section 110 that gradually imparts kinetic energy to the working fluid 106 to generate compressed, high-pressure (HP) air 112 (hereinafter "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 form a combustible mixture in at least one combustor 100 in a combustion section 120 operatively coupled to the compressor section 110. The combustible mixture is combusted to generate high-temperature, high-pressure combustion gases 122.

[0039] The combustion gases 122 flow through a turbine 128 of a turbine section 130 operably coupled to the combustion section 120 to generate 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 generate 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 an exhaust stack 140 downstream of the turbine 128. The exhaust section 138 may include, for example, a heat recovery steam generator (not shown) for cleaning and extracting additional heat from the exhaust gases 136 before being released to the environment. If multiple combustors 100 are used, they may be spaced circumferentially around a turbine inlet 142 of the turbine 128.

[0040] In one embodiment, the GT system 90 may include any engine model, such as those commercially available from GE Vernova of Cambridge, Massachusetts. The present disclosure is not limited to operability with any one particular GT system and may be implemented in connection with other engines, including, for example, any of GE Vernova's HA, F, B, LM, GT, TM, and E-class engine models, as well as engine models from other companies. Furthermore, the present disclosure is not limited to implementation with a particular turbomachine and may be applicable, for example, to steam turbines, jet engines, compressors, turbofans, etc.

[0041] A description will now be given of a combustor 100 that can be used within the GT system 90. Figure 2 illustrates a cross-sectional side view of the combustor 100 positioned 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 an embodiment of the present disclosure.

[0042] 2 , 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 outer casing 152 is in fluid communication with compressor discharge 109 of compressor 108 and forms HP air source 154. That is, HP air source 154 includes HP air 112 from the compressor discharge of compressor 108. HP source 154 is in direct fluid communication with compressor discharge 109 of GT system 90. However, HP air source 154 may be any source of HP air 112 that can enter any of the various openings or flow passages in combustor 100 for component cooling and / or combustion, i.e., within AFS injectors 150.

[0043] As shown in FIG. 2 , the combustor 100 for the GT system 90 includes a combustor body 160. The combustor body 160 can be fabricated using any now known or later developed technique. For example, the combustor body 160 can be additively manufactured. The combustor body 160 can include, for example, a combustion liner 164, which can include a cylindrical portion 166 and a tapered transition portion 168. The combustion liner 164 can have an axis A, the direction of which can vary slightly depending on the axial location within the curved combustion liner 164. The tapered transition portion 168 is at the aft end (to the right as shown in FIG. 2 ) of the cylindrical portion 166. As understood in the art, the tapered transition portion 168 transitions the hot gas path (HGP) from a circular cross-section of the liner's cylindrical portion 166 to a more arcuate cross-section for mating with the turbine inlet 142 of the turbine 128. The combustor 100 may also include an aft frame 170 at the aft end (to the right in FIG. 2) of the tapered transition section 168 .

[0044] Combustion liner 164 may contain and channel combustion gases 122 to turbine section 130 ( FIG. 1 ). More specifically, combustion liner 164 defines combustion chamber 172, i.e., the hot gas path (HGP), where combustion occurs. Combustion liner 164 may have a tapered transition portion 168 separate from cylindrical portion 166, as in many conventional combustion systems. Alternatively, as shown in FIG. 2 , combustion liner 164 may have a one-piece body (or “unibody”) construction in which cylindrical portion 166 and tapered transition portion 168 are integral with one another, i.e., as part of an additively manufactured, one-piece member. Thus, any description of combustion liner 164 herein is intended to encompass conventional combustion systems having separate cylindrical, tapered transition portions and / or combustion systems having a unibody liner.

[0045] 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) at a forward end (left end in FIG. 2 ) of the combustion liner 164 to a head-end fuel nozzle assembly 176 (hereinafter “head-end assembly 176” for brevity) of the combustor 100. That is, the airflow passage 174 is sized, shaped, and / or arranged to deliver air, such as the 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 within 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. Air flow passage 174 has an open end 178, or airflow opening, proximate head end assembly 176 through which HP air 112A from HP air source 154 enters, where HP air 112A from HP air source 154 may be drawn directly from the compressor discharge, i.e., without any other use of the air other than concurrent convective cooling of combustor body 160.

[0046] An annular partition 179, located between cylindrical portion 166 and flow sleeve 177, separates a forward portion of airflow passage 174 from an aft portion of airflow passage 174. The axial position of annular partition 179 is generally aligned with cap assembly 198, described below, so that the forward portion of airflow passage 174 is radially outward of head-end assembly 176 (rather than combustion chamber 172), thereby requiring less cooling. Aft of annular partition 179, flow sleeve 177 may include a plurality of impingement holes 192 (shown in outer sleeve 190) that allow HP air 112B to enter airflow passage 174. As a result of passing through impingement holes 192, HP air 112B experiences a pressure drop and becomes LP air 182, which flows through airflow passage 174 toward and / or into AFS injector 150, as described further herein.

[0047] Head end assembly 176 generally includes at least one axially-extending fuel nozzle 194 extending downstream from end cover 196 and a cap assembly 198 extending radially and axially within outer casing 152 downstream from end cover 196 and defining a forward boundary of combustion chamber 172. Head end assembly 176 may include any now known or later developed axially-extending fuel nozzle 200 for delivering first fuel 114A from axially-extending fuel nozzle 200 to primary combustion zone 202. In certain embodiments, axially-extending fuel nozzle 200 of head end assembly 176 extends at least partially through cap assembly 198 and provides a combustible mixture of fuel 114A and HP air 112A to primary combustion zone 202.

[0048] The combustor body 160 also includes axial fuel stage (AFS) injector openings or seats 180 directed toward 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, “openings 180”) may be provided and configured to receive the AFS injectors 150 mounted therein and receive the HP air 112B from the HP air source 154, among other airflows described herein. Each AFS injector opening 180 may include any structure operable to allow the AFS injector 150 to be mounted therein, such as threaded fasteners, bolt holes, welded areas, etc. As shown, the combustor 100 and combustor body 160 may include a plurality of circumferentially spaced AFS injector openings 180 and corresponding AFS injectors 150. Any number of AFS injectors 150 may be used.

[0049] As will be described, in certain embodiments, the AFS injector 150 is also configured to receive (draw) low-pressure (LP) air 182 from a low-pressure (LP) air source 184, e.g., a cooling passage, and direct it along with fuel 114B to the combustion liner 164. The fuel 114B may be delivered from the fuel source 116 using any form of fuel line 188. The fuels 114A, 114B may be any now known or later developed fuel for the combustor 100, 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.

[0050] In several embodiments, LP air 182 can be delivered to AFS injectors 150 from LP air source 184 in various ways. In certain embodiments, LP air 182 originates from HP air source 154 but is used for cooling before use in AFS injectors 150. In one example, combustor body 160 further includes a cooling passage 186 defined at least in part by tapered transition portion 168 that provides LP air source 184. Cooling passage 186 may also be in fluid communication with other cooling passages (not shown) within combustor 100. In either case, LP air 182 from LP air source 184 can be used to cool one or more high-temperature components of combustor 100. More specifically, LP air 182 from LP air source 184 passes through cooling passage 186 defined at least in part by tapered transition portion 168 after being drawn from the compressor discharge.

[0051] In one example, the cooling passage 186 may be formed by a flow sleeve 190 or within the tapered transition portion 168. If desired, impingement cooling holes 192 may be provided in the flow sleeve 190 surrounding the tapered transition portion 168 to allow HP air 112 to enter from the HP air source 154 and become the LP air 182. In this regard, the LP air source 184 includes the cooling passage 186 defined along at least a portion of the combustion liner 164, e.g., the tapered transition portion 168. Additionally, the cooling passage 186 may optionally be downstream of the compressor discharge 109 of the GT system 90, i.e., an impingement cooling member (the portion 168 having the impingement cooling holes 192 in its outer sleeve or a sleeve around the portion 168 having the holes 192 therein) in direct fluid communication with the HP air source 154. It should be noted that the hot components 84 may include any portion of the combustor 100 requiring cooling, the LP air 182 may be directed to enter the cooling passages in any manner desired, and the cooling passages 186 may be defined in or along (other) hot components of the combustor 100 other than the tapered transition portion 168 (e.g., the aft frame 170). In either case, the 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 provide significant cooling of the components of the combustor 100, it may also be referred to herein as “post-cooling” or “post-impingement air.” It is emphasized that although LP air 182 is described herein as cooled air, it may be any air having a lower pressure than HP air 112, and that LP air source 184 may be other than that described herein.

[0052] As described above, the combustor 100 includes at least one axially staged fuel injector (AFS) 150 directed to the combustor body 160, i.e., the combustion liner 164. As described above, the AFS injector 150 may include a plurality of AFS injectors 150 spaced circumferentially around the combustor body 160. Each AFS injector 150 extends radially through the combustion liner 164 downstream of the head end assembly 176, i.e., downstream of the axially extending fuel nozzles 200. As will be further described, the AFS injector 150 is configured to receive HP air 112B from the HP air source 154 and, optionally, draw LP air 182 from the LP air source 184. In certain embodiments, the LP air 182 from the LP air source 184 may be routed to, for example, the AFS injector 150 in the cooling passage 186 to be combined with the HP air 112B and the second fuel 114B for combustion in a secondary combustion zone 204 downstream of the primary combustion zone 202.

[0053] FIGS. 3-7D 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 in FIG. 3. FIG. 5A shows a cross-sectional view taken along line 5-5 in FIG. 3. FIG. 5B shows a cross-sectional view taken along line 5-5 in FIG. 3 of an alternative embodiment. The AFS injector 150 includes a mixing element 210 and a high-pressure (HP) air injection element 212. Top views of the mixing element 210 according to various embodiments are shown in FIGS. 6A-6C, and top views of the HP air injection element 212 according to various embodiments are shown in FIGS. 7A-7D. The mixing element 210 and the HP air injection element 212 are coupled together to form the AFS injector 150. 3-5, the mixing element 210 and the HP air injection element 212 may each include a mounting element 213 configured to receive a fastener 215, such as a bolt or a weld, to couple the mixing element 210 and the HP air injection element 212 to the combustion liner 164, such as to an AFS injector mount 274 of the combustion liner 164. Alternatively, the mixing element 210 and the HP air injection element 212 may be formed as a single, integral piece, such as by additive manufacturing. Each AFS injector 150 is aligned with a respective opening 180 in the combustion liner 164.

[0054] As shown in FIGS. 3-5 and 6A-6C, the mixing element 210 includes a plurality of mixing chambers 214 defined therein. The mixing element 210 may also be referred to as an injector body. As shown in FIGS. 3-5, each mixing chamber 214 includes an inlet 216 and an outlet 218. Each inlet 216 is radially inward of an HP air injection member 212 (hereinafter sometimes referred to as an "injection member 212" for brevity), and the outlets 218 are configured to be in fluid communication with the combustion liner 164 of the combustor 100 (FIG. 2). More specifically, the outlets 218 may be positioned and secured to openings 180 in the combustion liner 164.

[0055] The mixing chambers 214 can take a variety of forms. In the example shown in the drawings, each mixing chamber 214 of the multiple mixing chambers has a cylindrical shape, i.e., they are generally tubular. However, other cross-sectional shapes are also possible, such as elliptical, oval, among others. Furthermore, some curvature and / or narrowing from the inlet 216 to the outlet 118 may be provided, if desired.

[0056] 5A , each of the plurality of mixing chambers 214A-C may be inclined at a non-perpendicular angle α relative to the axis A of the combustion liner 164 (and the flow direction of the combustion gases 122 therein) to direct the air-fuel mixture injected by the AFS injector 150 downstream in the combustion liner 164. The inclination of the mixing chamber 214 also reduces the size of the AFS injector 150. In addition, the inclination of the mixing chamber 214 may also allow the plurality of mixing chambers 214 to function as if they were a single mixing chamber, for example, by directing the air-fuel mixture 250 exiting the outlet 218 of the mixing chamber 214 to a single location. More specifically, at least one of the plurality of mixing chambers 214A-C may be inclined at an obtuse angle α, α, or α relative to the axis A of the combustion liner 164 (and the flow direction of the combustion gases 122 therein). In certain embodiments, at least one mixing chamber 214D at the most downstream axial location along the combustion liner 164 may be perpendicular (angle α4) to the axis A of the combustion liner 164. From the most upstream mixing chamber 214A at obtuse angle α1, the subsequent obtuse angles α2, α3 may gradually approach perpendicular. That is, mixing chamber 214A has a larger obtuse angle α1 than the obtuse angle α2 of the downstream mixing chamber 214B, which has a larger obtuse angle α2 than the obtuse angle α3 of the downstream mixing chamber 214C, which has an obtuse angle α3 that is larger than the perpendicular angle α4 of the most downstream mixing chamber 214D.

[0057] In other embodiments, when more mixing chambers 214 are used, such as two rows of eight mixing chambers 214A-H (see also FIG. 6B) as shown in FIG. 5B, the inclination of mixing chambers 214A-H may differ from that shown in FIG. 5A. For example, in a 2×8 mixing chamber arrangement, mixing chambers 214A-D may be at an obtuse angle relative to axis A of combustion liner 164 and may be inclined downstream, and mixing chambers 214E-H may be at an obtuse angle relative to axis A of combustion liner 164 and may be inclined upstream. Thus, mixing chambers 214A-D can be considered as mirror images of mixing chambers 214E-H, for example, through a radial line passing through sidewall 222 between mixing chambers 214D and 214E.

[0058] As shown in FIG. 4 , the mixing chambers 214 may also be inclined relative to a radial direction R relative to the axis A of the combustion liner 164, i.e., in the circumferential plane (the plane of the paper in FIG. 4 ). That is, the centerline of the mixing chambers 214 is not parallel to or coextensive with the radius (R) relative to the axis A of the combustion liner 164. For example, a row of mixing chambers 214-1, 214-2 (extending into and out of the plane of the paper in FIG. 4 ) may be inclined to direct the air-fuel mixture 250 exiting an adjacent row of mixing chambers 214 toward the axis A of the combustion liner 164. If two rows of mixing chambers 214-1, 214-2 are used, the mixing chambers 214-1 of the first row may be inclined at an angle γ1 relative to the radial direction R, and the second row of mixing chambers 214-1 may be inclined at an angle γ2 relative to the radial direction R. It will be appreciated that the inclination in the circumferential plane may vary depending on the number of rows of mixing chambers 214 used.

[0059] The number and arrangement of mixing chambers 214 may vary based on, for example, the fuel 114B used and the size of the combustor 100, among other factors. As shown in FIG. 6A, the mixing chambers 214 may be arranged in a 2×4 arrangement with two rows of four mixing chambers 214A-1, 214B-1, 214C-1, 214D-1, and 214A-2, 214B-2, 214C-2, 214D-2. FIGS. 6B-6C show only two examples of possible alternative arrangements (i.e., a 2×8 arrangement and a 3×12 arrangement, respectively). It is emphasized that the scope of this disclosure includes other arrangements not explicitly shown.

[0060] Figure 6B shows an embodiment including two rows of eight mixing chambers 214. That is, eight mixing chambers 214A-1 through 214H-1 are arranged in a first row, and eight mixing chambers 214A-2 through 214H-2 are arranged in a second row. Figure 5B shows a cross-sectional view of one embodiment of this arrangement. The mixing chambers 214 in each row are axially aligned with one another, although the mixing chambers 214 in the first row may be axially offset from the mixing chambers 214 in the second row relative to the axis of the combustion liner.

[0061] FIG. 6C illustrates an embodiment including three rows of twelve mixing chambers 214. That is, twelve mixing chambers 214A-1 through 214L-1 are arranged in a first row, twelve mixing chambers 214A-2 through 214L-2 are arranged in a second row, and twelve mixing chambers 214A-3 through 214L-3 are arranged in a third row. The mixing chambers 214 in the first row may be axially offset from the mixing chambers 214 in the second row and axially aligned with the mixing chambers 214 in the third row relative to the axis of the combustion liner. The mixing chambers 214 in FIGS. 6B-6C may also have an obtuse angle of inclination as described with respect to FIG. 5A and a gradually decreasing inclination relative to the radial direction R as described with respect to FIG. 4.

[0062] 3-5B , the AFS injector 150 also includes a fuel plenum 220 defined in the mixing element 210. The fuel plenum 220 may extend into an upstream portion of a sidewall 222 (hereinafter, the “upstream sidewall 222”) of each of the multiple mixing chambers 214, or at least an upstream portion of the sidewall 222 of any required mixing chamber 214 operable to supply fuel 114B to the desired mixing chamber 214. Furthermore, the fuel plenum 220 may extend around each mixing chamber 214 to any extent to deliver fuel to locations where a set of fuel injectors 230 are located. The AFS injector 150 also includes an inlet port 226 in fluid communication with the fuel plenum 220 and configured to receive fuel 114B from the fuel source 116 ( FIGS. 1-2 ). The inlet port 226 of each AFS injector 150 may be fluidly coupled to the fuel source 116, for example, by the fuel line 188 and, optionally, a distribution plenum (not shown) around the combustion liner 164. In either case, the fuel plenum 220 is configured to deliver the fuel 114B from the fuel source 116 to each set of fuel injectors 230. The fuel 114B may be any now known or later developed fuel for the combustor 100, such as, but not limited to, natural gas. With the benefit of the AFS injectors 150, the fuel 114B may also include a highly reactive fuel, such as hydrogen. The fuel 114B may also include a blend of fuels, such as natural gas and hydrogen.

[0063] The mixing element 210 also includes a set of fuel injectors 230 defined in the upstream wall 222 of each mixing chamber 214. Each fuel injector 230 is in fluid communication with the fuel plenum 220 so that fuel 114B can be introduced into the respective mixing chamber 214, i.e., under pressure from the fuel source 116. In certain embodiments, each set of fuel injectors 230 includes a first set of fuel injectors 230A that are axially spaced (relative to the axis of the respective mixing chamber 214) from a second set of fuel injectors 230B in each mixing chamber 214 of the multiple mixing chambers. 5A and 5B, a first set of fuel injectors 230A may be spaced a first distance D1 from the outlet 218 of a respective mixing chamber 214, and a second set of fuel injectors 230B may be spaced a second distance D2 less than the distance D1 from the outlet 218 of a respective mixing chamber 214 of the plurality of mixing chambers. As shown, each set of fuel injectors 230A-B may be closer to the inlet 216 than to the outlet 218 of a respective mixing chamber 214 of the plurality of mixing chambers. Although two axially spaced sets of fuel injectors 230A-230B are used, three or more sets of axially spaced fuel injectors are also possible.

[0064] The fuel injectors 230 can take any now known or later developed form of opening for delivering a particular type of fuel 114B to the respective mixing chambers 214. For example, the fuel injectors 230 can be cylindrical openings or can have a narrowed nozzle cross-section to distribute the fuel 114B. Additionally, the fuel injectors 230 can introduce the fuel 114B into the respective mixing chambers 214 in any desired direction. For example, the fuel injectors 230 can introduce the fuel 114B into the respective mixing chambers 214 at a perpendicular angle relative to the axis of the respective mixing chamber 214 and / or its upstream wall 222, at a non-perpendicular angle relative to the upstream wall 222 to impart rotation to the fuel 114B, and / or radially outward or inward relative to the axis of the respective mixing chamber 214, i.e., toward or away from the combustion liner 164.

[0065] The fuel injectors 230 within a given set may also have any spacing, e.g., uniform or non-uniform spacing, circumferentially around the respective mixing chamber 214. In either case, as will be further described, each set of fuel injectors 230 is configured to entrain fuel 114B in the airflow from the injection member 212 to create a desired air-fuel mixture 250 for combustion in the combustion liner 164. The type, number, spacing, and size of the fuel injectors 230 overall and within a given set may be selected depending on, for example, a wide variety of characteristics of the combustor 100, the HP and LP air 112B, 182, and / or the fuel 114B. For example, with respect to the fuel 114B, the characteristics may include, but are not limited to, gas type, level of reactivity, viscosity, energy density, desired flow rate or volume, pressure, temperature, etc. The fuel injectors 230 within a given set need not be identical, and the fuel injectors 230 within a set need not be identical to one another. In terms of numbers, in one non-limiting example, the set of fuel injectors 230A in each respective mixing chamber 214 can include three fuel injectors and the set of fuel injectors 230B can include six fuel injectors. Other numbers of fuel injectors 230 are also possible.

[0066] The dimensions of the mixing chambers 214 can be user-defined based, for example, on the characteristics of the fuel 114B, HP air 112B, LP air 182, and / or combustion liner 164, among many other factors. Despite the different angles, the length L of each mixing chamber 214 from the inlet 216 to the outlet 218 (shown in FIG. 5A only in mixing chamber 214C for clarity) is generally the same. The dimensions of any portion of the mixing element 210 (and HP air injection element 212) of the AFS injector 150 can be customized to produce a desired air-fuel mixture 250.

[0067] 3-5B, 7A-7D, and 8, the HP air injection member 212 will now be described. Note that the injection member 212 may also be referred to as a "top hat." The injection member 212 defines a set 240 of HP air jets 242 (e.g., one set for each mixing chamber 214). The outlets of the HP air jets 242 are spaced from the inlets 216 of each mixing chamber 214 when the AFS injector 150 is assembled. There are as many sets 240 of HP air jets 242 within the injection member 212 as there are mixing chambers 214 in a given mixing element 210. For example, as shown in FIG. 7A, two rows of four sets 240 of HP air jets 242 are shown, i.e., sets 240A-1 through 240D-1 and sets 240A-2 through 240D-2, corresponding to the two rows of four mixing chambers 214 in FIG. 6A. 5B and 6B, which includes two rows of eight mixing chambers 214A-H, two rows of eight sets 240 of HP air jets 242, i.e., sets 240A-1 through 240H-1 and 240A-2 through 240H-2, can be used, as shown in FIG. 7B. The injection member 212 is in fluid communication with the HP air source 154 so that the HP air 112B enters and is directed by the sets 240 of HP air jets 242.

[0068] As illustrated, each set 240 of HP air jets 242 is configured to direct HP air 112B from HP air source 154 and, optionally, draw LP air 182 from LP air source 184, and direct the LP air 182 along with the HP air 112B to the inlet 216 of the respective mixing chamber 214. The collective flow is referred to herein as HP air flow 244, see the arrows in FIGS. 4-5B that extend toward the inlet 216 of the respective mixing chamber 214. Thus, HP air flow 244 includes HP air 112B and LP air 182. Note that HP air flow 244 maintains a relatively high pressure, though not as high as HP air 112B from HP air source 154, such as compressor discharge 109 (FIG. 2), and is therefore referred to as high pressure despite its mixing with LP air 182.

[0069] 3-5, the injection member 212 may optionally include a filter element 246 upstream (radially outward) of the set of HP air jets 242. Note that the filter element 246 is not shown in FIGS. 7A-7D for clarity. The filter element 246 may include any now known or later developed filter structure capable of preventing undesirable contaminants from entering the AFS injector 150 from the HP air source 154.

[0070] Each set 240 of HP air jets 242 can include any number of HP air jets 242. In the example shown in Figures 3-5B and 7A, each set 240 of HP air jets 242 includes three HP air jets 242A-C. Figure 7C shows a set 240 that each includes two HP air jets 242, and Figure 7D shows a set 240 that each includes four HP air jets 242. In the example shown, each HP air jet 242 can have a circular cross-sectional shape, but can alternatively have a cross-sectional shape such as, but not limited to, an oval, an elongated opening or slot, or a narrow longitudinal cross-section (nozzle or venturi-like).

[0071] With respect to the intake of HP air 112B from the HP air source 154, a set 240 of HP air jets 242 are spaced apart from the inlet 216 of each mixing chamber 214 and configured to direct an HP air stream 244 (see arrows) comprising the HP air 112B therefrom into the respective mixing chamber 214. As noted above, the injection member 212 is in fluid communication with the HP air source 154 such that the HP air 112B enters the HP air jets 242. The set 240 of HP air jets 242 are spaced apart from the inlet 216 of each mixing chamber 214 and configured to direct the HP air 112B therefrom and, in some embodiments, draw LP air 182 therein to form the HP air stream 244.

[0072] The HP jets 242 also direct HP airflow 244 into each mixing chamber 214. More specifically, the HP jets 242 can direct the HP airflow 244 into each mixing chamber 214 at an angle substantially identical to the angle of the respective mixing chamber 214. For example, the HP jets 242 can direct the HP airflow 244 into each mixing chamber 214 at an angle identical to the obtuse angle α of the respective mixing chamber 214. That is, the HP airflow 244 is at the same angle as the obtuse angle α of the respective mixing chamber 214. While each HP jet 242 in a set does not necessarily have to have the angle α of its respective mixing chamber 214, the HP air jets 242 in a given set 240 are each angled such that the collective HP airflow 244, including the HP air 112B and LP air 182 (if used) from the given set, has an angle (not shown for clarity) identical to the obtuse angle α of the respective mixing chamber 214. More specifically, as shown in FIG. 5A, the HP air flows 244 from the HP air jets 242 of set 240A have an obtuse angle α1 in the mixing chamber 214A, the HP air flows 244 from the HP air jets 242 of set 240B have an obtuse angle α2 in the mixing chamber 214B, the HP air flows 244 from the HP air jets 242 of set 240C have an obtuse angle α3 in the mixing chamber 214C, and the HP air flows 244 from the HP air jets 242 of set 240D have an obtuse angle α4 (perpendicular to the axis A of the combustion liner 164) in the mixing chamber 214D.

[0073] FIG. 8 illustrates a cross-sectional view of a pair of HP air jets 242A, 242B of a selected set 240C-1 along view line 8-8 of FIG. 7A. Collectively as set 240, each HP air jet 242 can be set at an angle β (relative to axis A of combustion liner 164) to direct HP air flow 244 at a desired angle to the inlet 216 of the respective mixing chamber 214. For example, as shown in FIG. 7A, HP air jet 242A is set at angle β1 and HP air jet 242B is set at angle β2. Although not shown, HP air jet 242C of the same set 240C-1 is set at angle β3. Angles β1-β3 can be set based on, for example, the flow rates, flow volumes, pressures, and / or temperatures of HP air 112B and LP air 182.

[0074] 3-5, the mixing chambers 214 mix the HP air flow 244 with the fuel 114B entering from the fuel injectors 230. As described above, each HP air jet 242 is configured to direct the HP air flow 244 toward the inlet 216 of the respective mixing chamber 214, which contains the HP air 112B from the HP air source 154. In some embodiments, each HP air jet 242 is configured to draw LP air 182 from the LP air source 184 into the space between the HP air jet 242 and the mixing element 210, i.e., to form an ejector for the LP air 182. The HP air flow 244 impinges on the inlet 216 of the mixing chamber 214, or more precisely, on the leading edge of the mixing chamber 214, creating a vortex and promoting in-plane mixing (in the plane of the top surface of the mixing element 210) of the HP air 112B, the LP air 182, and the fuel 114B. In one non-limiting example, HP air 112B can comprise between 45% and 55% of the airflow to the injector provided by the sum of HP airflow 244 and LP airflow 182, and LP air 182 can comprise between 45% and 55% of the airflow to the injector provided by the sum of HP airflow 244 and LP airflow 182. In this manner, AFS injector 150 using two air sources reduces pressure losses throughout the system and more efficiently uses the air within combustor 100.

[0075] The AFS injector 150, i.e., the mixing element 210 and the injection element 212, can be made of any now known or later developed combustion- and oxidation-resistant material. The material can be a metal, either a pure metal or an alloy. The AFS injector 150 can include metals typically used in turbine components, such as turbine blades or nozzles, that have higher temperature and oxidation resistance than materials typically used in combustion hardware. In this case, the material may include, for example, but is not limited to, a non-reactive metal made from 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 a nickel-chromium-molybdenum-niobium alloy (NiCrMoNb) (e.g., Inconel 625 or Inconel 718), a nickel-chromium-iron-molybdenum alloy (NiCrFeMo) (e.g., Hastelloy® X available from Haynes International, Inc.), a nickel-chromium-cobalt-molybdenum alloy (NiCrCoMo) (e.g., Haynes 232 or Haynes 282 available from Haynes International, Inc.), or a nickel-chromium-cobalt-titanium alloy (Ni—Cr—Co—Ti) (e.g., GTD 262 developed by General Electric Company). Other possibilities include, for example, Rene 108, CM 247, Mar M 247, and any precipitation hardenable (PH) nickel alloy.

[0076] In certain embodiments, the AFS injector 150, i.e., the mixing element 210 and / or the injection element 212, can be additively manufactured using any now-known or later-developed technique capable of forming a unitary body. Thus, as shown in FIG. 9 , the mixing element 210 and / or the injection element 212 includes multiple parallel sintered metal layers 270. FIG. 10 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, of which only a single layer is shown. While the teachings of the present disclosure are described with respect to constructing the mixing element 210 and / or the injection element 212 using multiple melt beam sources 312, 314, 316, 318, it is emphasized, and it will be readily appreciated, that the teachings of the present disclosure are equally applicable to constructing 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). It is understood that the general teachings of the present disclosure are equally applicable to other forms of metal powder additive manufacturing, such as, but not limited to, selective laser melting (SLM), and possibly other forms of additive manufacturing (i.e., other than metal powder applications). While the layers of mixing elements 210 and / or injection elements 212 on the build platform 320 are shown as circular elements in FIG. 10 , it is understood that the additive manufacturing process can be readily adapted to produce any shape on the build platform 320.

[0077] The AM system 310 generally includes an additive manufacturing control system 330 (“control system”) and an AM printer 332. As illustrated, the control system 330 executes a set of computer-executable instructions or code 334 for generating the mixed member 210 and / or the jetting member 212 using multiple melt beam sources 312, 314, 316, 318. In the illustrated example, the four melt beam sources may include four lasers. However, the teachings of the present disclosure are applicable to any melt beam source, e.g., electron beam, laser, etc. The control system 330 is shown implemented in a computer 336 as computer program code. In this context, the computer 336 is shown as including 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 computer 336 is shown as communicating with an external I / O device / resource 350.

[0078] Generally, processor unit (PU) 344 executes computer program code 334 stored in memory 338 and / or storage system 340. While executing computer program code 334, processor unit (PU) 344 can read and write data from memory 338, storage system 340, I / O devices 350, and / or AM printer 332. Bus 348 provides a communication link between each of the components in computer 336, and I / O devices 350 can comprise 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 can comprise a single processing unit or can be distributed across one or more processing units at one or more locations, e.g., on a client and a server. Similarly, memory 338 and / or storage system 340 may reside in one or more physical locations. The 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. The 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.

[0079] As described above, the AM system 310, and particularly the control system 330, executes code 334 to generate the mixing element 210 and / or the jetting 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, as well as a set of computer-executable instructions 334O (also referred to herein as “code 334O”) that define the mixing element 210 and / or the jetting element 212 that are physically generated 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.) storing 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.

[0080] 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®, DesignCAD 3D Max, etc. In this regard, the code 334O may include any now known or later developed file format. 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 generated for a 3D systems stereolithography CAD program, or an Additive Manufacturing File (AMF), an extensible markup language (XML)-based format standardized by the American Society of Mechanical Engineers (ASME) and designed to allow any CAD software to describe the shape and configuration of any three-dimensional object to be produced on any AM printer. The code 334O representing the mixing element 210 and / or the injection element 212 may also be converted into a set of data signals, transmitted, received as a set of data signals, converted into code, stored, etc., as needed. The code 334O may be configured according to embodiments of the present disclosure to enable the formation of boundaries and interior sections within overlapping field regions, as described. In either case, the code 334O may be input to the AM system 310 and may come from a part designer, intellectual property (IP) provider, design firm, operator or owner of the AM system 310, or other source. In either case, the control system 330 executes the code 334S and 334O to divide the mixing element 210 and / or the injection element 212 into a series of thin slices, which are assembled in successive layers of material using the AM printer 332.

[0081] The AM printer 332 can include a sealed 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 positioned within the processing chamber 360. Several 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 shown, it is emphasized that the teachings of the present disclosure are applicable to systems using any number of sources, for example, one, two, three, or five or more sources. As understood in the art, each melt beam source 312, 314, 316, 318 can have fields that each include a non-overlapping field region capable of melting only metal powder, and two or more sources can include at least one overlapping field region capable of melting metal powder. In this regard, each melt beam source 312, 314, 316, 318 can generate a respective melt beam that melts particles for each slice, as defined by code 3340. For example, in FIG. 10, melt beam source 312 is shown using melt beam 362 to generate layers of mixing element 210 and / or injection element 212 in one region, and melt beam source 314 is shown using melt beam 362′ to generate layers of mixing element 210 and / or injection element 212 in another region.

[0082] Each melt beam source 312, 314, 316, 318 is calibrated in any now known or later developed manner, i.e., each melt beam source 312, 314, 316, 318 correlates the expected position of its laser or electron beam with its actual position relative to the build platform 320 to provide individual position corrections (not shown) to ensure its individual accuracy. In one embodiment, each of the multiple melt beam sources 312, 314, 316, 318 can generate melt beams, e.g., 362, 362′, having the same cross-sectional dimensions (e.g., shape and size during operation), power, and scan speed.

[0083] 10 , an applicator (or recoater blade) 370 produces a thin layer of raw material 372, which is laid out as a blank canvas from which each successive slice of the final mixed element 210 and / or jet element 212 will be produced. Various parts of the AM printer 332 may move to accommodate the addition of each new layer; for example, after each layer, the build platform 320 may lower and / or the chamber 360 and / or applicator 370 may raise. The process may use different raw materials in the form of fine metal powder, a stock of which may be held in a powder reservoir 368 accessible by the applicator 370.

[0084] The processing chamber 360 is filled with an inert gas, such as argon or nitrogen, and controlled to reduce or eliminate oxygen. The control system 330 is configured to control the flow of a gas mixture 374 into the processing chamber 360 from an inert gas source 376. In this case, the control system 330 can 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 can include one or more computer-controllable valves, flow sensors, temperature sensors, pressure sensors, etc., capable of precisely controlling the flow of specific gases. The pump 380 may or may not include the valve system 382. If the pump 380 is omitted, the inert gas can enter a conduit or manifold before being introduced into the processing chamber 360. The inert gas source 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.

[0085] During operation, a build platform 320 having metal powder thereon is provided within a processing chamber 360, and a control system 330 controls the flow of a gas mixture 374 within the processing chamber 360 from an inert gas source 376. The control system 330 also controls the AM printer 332, and in particular the applicator 370 and melt beam sources 312, 314, 316, 318, to sequentially melt layers of metal powder on the build platform 320 to produce the mixed element 210 and / or the jet element 212 according to embodiments of the present disclosure. While a particular AM system 310 is described herein, it is emphasized that the teachings of the present disclosure are not limited to any particular additive manufacturing system or method.

[0086] Once the mixing element 210 and the injection element 212 are formed, they may 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 injection element 212 may each include a mounting element 213 configured to receive a fastener 215, such as a bolt or a weld, to couple the mixing element 210 and the HP air injection element 212 to the AFS injector mount 274 on the combustion liner 164.

[0087] 3-5B, the periphery of the HP injection member 212 rests on the outer surface of the forward flow sleeve 177 or the aft flow sleeve 190, and the mixing member 210 extends outward from the combustion liner 164 within openings in the flow sleeves 177, 190. A gap may be defined between the inner surface of the HP air injection member 212 and the mixing member 210, thereby permitting the flow of LP air 182 from the openings into the interior of the AFS injector 150. In such an embodiment, the LP air 182 is entrained in the HP air 112B flowing through the HP injection member 212.

[0088] In other embodiments (not shown), the use of LP air 182 can be omitted by blocking the flow from the LP air source 184 to the AFS injector 150 so that the AFS injector 150 is not in fluid communication with the LP air source 184. In such embodiments, the mixing element 210 and / or the injection element 212 can include an axially extending wall extending between the mixing element 210 and the inner surface of the HP injection element 212. This wall prevents LP air 282 from entering the mixing chamber 214. More specifically, this wall defines a sealed chamber between the mixing element 210 and the injection element 212 that prevents any additional (LP) air from entering the air-fuel mixture 236 exiting the HP air-fuel injector 232. An AFS injector 150 configured in this manner uses only HP air 112B to mix with fuel and does not receive post-impingement air as LP air 182.

[0089] Embodiments of the present disclosure may also include a combustor 100 for the GT system 90. The combustor 100 includes a combustor body 160 including a combustion liner 164. The combustor 100 may also include a plurality of AFS injectors 150 directed at the combustion liner 164, as described herein. Returning to FIG. 2 , the combustor 100 generally terminates at a point adjacent a first stage 260 of a static nozzle 262 of the turbine 128. The first stage 260 of the static nozzle 262 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 the 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. Due to its small size, the AFS injector 150 can be assembled onto 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 (within the casing 152).

[0090] 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 at least one combustor 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 also include a plurality of AFS injectors 150 directed into the combustor body 160, i.e., the combustion liner 164, downstream of the head-end assembly 176, as described herein.

[0091] The present disclosure provides various technical and commercial advantages, examples of which are described herein. As described herein, AFS injectors can accept high-pressure air and, optionally, low-pressure air, such as post-impingement cooling air or other low-pressure air, to reduce pressure losses throughout the system. The AFS injectors can rapidly premix an air source with a highly reactive fuel, such as hydrogen, to achieve, for example, low nitrous oxide (NOx) emissions and acceptable flame-holding capabilities. The AFS injectors enhance fuel-air mixing, reduce flow pressure losses, and prevent fuel from entering any low-velocity airflow zones. Additionally, the AFS injectors have a relatively small radial height from top to bottom, allowing them to be assembled onto the combustion liner of the combustor body, which is then axially installed in the GT system through a relatively small opening in the compressor discharge casing.

[0092] As used herein throughout this specification and claims, approximation language can be applied to modify any quantitative expression that can reasonably vary without resulting in a change in the relevant basic function. Thus, values ​​modified by terms such as "approximately," "about," and "substantially" are not limited to the exact value specified. In at least some instances, approximation language can correspond to the precision of the instrument used to measure the value. Here, and throughout this specification and claims, range limitations are combinable and / or interchangeable, and unless the context or language dictates otherwise, such ranges are identified and include all subranges encompassed therein. "About" or "approximately," as applied to a particular value in a range, applies to both endpoints and can indicate + / - 10% of the stated value, unless specifically dependent on the precision of the instrument used to measure the value.

[0093] Corresponding structure, materials, acts, and equivalents of all means or step-plus-function elements in the following claims are intended to include any structure, material, or acts for performing the function in combination with other claimed elements that are specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the disclosed form. Many 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 were chosen and described to best explain the principles of the disclosure and practical applications of the technology, and to enable those skilled in the art to understand the disclosure in order to consider various modifications to the present embodiments that may be suitable for the particular use contemplated. [Explanation of symbols]

[0094] 84 High-Temperature Parts 90 Gas Turbine (GT) System 100 Combustor 102 Entrance Section 106 Working fluid (air) 108 Compressor 109 Compressor discharge port 110 Compressor Section 112 HP air 112A HP Air 112B HP Air 114A First Fuel 114B Secondary Fuel 116 Fuel source 118 Exit 120 Combustion Section 122 Combustion Gas 128 Turbine 130 Turbine Section 132 Shaft 134 Generator 136 Exhaust Gas 138 Exhaust Section 140 exhaust stack 142 Turbine inlet 150 Axial Fuel Stage (AFS) Injector 152 outer casing 154 HP Air Source 160 Combustor body 162 One-piece components 164 Combustion Liner 166 Cylindrical section 168 Tapered Transition 170 rear frame 172 Combustion Chamber 174 Air flow path 176 Head End Fuel Nozzle Assembly 177 Flow Sleeve 178 Open end 180 AFS injector opening or seat 182 Low Pressure (LP) Air 184 Low Pressure (LP) Air Source 186 Cooling passage 188 fuel line 190 Flow Sleeve 192 Impingement cooling hole 194 Axially extending fuel nozzle 196 End cover 198 End Cap Assembly 200 axially extending fuel nozzle 202 Primary Combustion Zone 204 Secondary Combustion Zone 210 Mixed materials 212 High-pressure (HP) air injection element 213 elements 214 Mixing Chamber 214-1 Mixing Chamber 214-2 Mixing Chamber 214A-H Mixing Chamber 214A-1 Mixing Chamber 214A-2 Mixing Chamber 214A-3 Mixing Chamber 214B-1 Mixing Chamber 214B-2 Mixing Chamber 214C-1 Mixing Chamber 214C-2 Mixing Chamber 214D-1 Mixing Chamber 214D-2 Mixing Chamber 215 Fasteners 216 Entrance 218 Exit 220 Fuel Plenum 222 Side wall 226 Inlet Port 230 fuel injector 230A fuel injector 230B Fuel Injector 240 HP air jet set 240A group 240A-1 set 240B group 240C group 240C-1 set 240D group 242 HP Air Jet 242A HP Air Jet 242B HP Air Jet 242C HP Air Jet 244 HP airflow 246 Filter material 250 air fuel mixture 260 First Section 262 Stationary Nozzle 270 Metal layer 274 AFS injector mount 310 Computerized Metal Powder Additive Manufacturing (AM) System 310' AM System 312 Melting Beam Source 314 Melting Beam Source 316 Melting Beam Source 318 Melting Beam Source 320 Building Platform 330 Additive Manufacturing (AM) Control System 332 AM Printer 334 Computer Program Code 334O Computer executable instructions or code 334O' computer executable instructions or code 334S Computer executable instructions or code 334S' computer executable instructions or code 336 Computer 338 memory 340 Memory System 344 Processor Unit (PU) 346 Input / Output (I / O) Interface 348 Bus 350 I / O devices / resources 360 Processing Chamber 362 Melting Beam 362' molten beam 372 raw materials 374 Gas Mixtures 376 Inert Gases 380 Pump 382 Flow Valve System 386 filters

Claims

1. 1. An axial fuel stage (AFS) injector (150) for a combustor (100) of a gas turbine (GT) system (90), comprising: A mixing element (210), a plurality of mixing chambers (214) defined in the mixing element (210), each mixing chamber (214) including an inlet (216) and an outlet (218), each outlet (218) configured to be in fluid communication with a combustion liner (164) of the combustor (100); a pair of fuel injectors (230) defined in the sidewall (222) of each mixing chamber (214); a mixing element (210) comprising: a high pressure (HP) air injection element (212) defining a set of HP air jets (240) spaced apart from the inlet (216) of each mixing chamber (214); a fuel plenum (220) defined in the mixing element (210), the fuel plenum (220) configured to deliver fuel (114A, 114B) from a fuel source (116) to a respective pair of fuel injectors (230); Equipped with each set of HP air jets (240) is configured to direct HP air (112) from an HP air source (154) to the inlets (216) of respective mixing chambers (214) into which fuel (114A, 114B) is injected by the set of fuel injectors (230); AFS injector (150).

2. The AFS injector (150) of claim 1, wherein at least one of the plurality of mixing chambers (214) is inclined at an obtuse angle relative to an axis of the combustion liner (164).

3. 2. The AFS injector of claim 1, wherein the set of HP air jets spaced from the inlet of each mixing chamber are configured to direct HP air flows into the respective mixing chamber at an angle identical to an angle of the respective mixing chamber.

4. The AFS injector (150) of claim 1, wherein the fuel plenum (220) is defined in the mixing element (210).

5. 5. The AFS injector of claim 4, wherein each respective mixing chamber defines an axis between its inlet and outlet, and each set of fuel injectors includes a first set of fuel injectors axially spaced from a second set of fuel injectors in a respective mixing chamber of the plurality of mixing chambers.

6. The AFS injector (150) of claim 4, wherein the fuel plenum (220) extends into an upstream wall (222) of each of the plurality of mixing chambers (214).

7. The AFS injector (150) of claim 4, wherein each set of fuel injectors (230) is closer to the inlet (216) than to the outlet (218) of each mixing chamber of the plurality of mixing chambers (214).

8. The AFS injector (150) of claim 1, wherein each mixing chamber of the plurality of mixing chambers (214) has a cylindrical shape.

9. The AFS injector (150) of claim 1, wherein the plurality of mixing chambers (214) are arranged in two rows of eight mixing chambers.

10. The AFS injector (150) of claim 1, wherein each set of HP air jets (240) comprises three HP air jets.

11. The AFS injector (150) of claim 1, wherein each HP air jet (240) has a circular cross-sectional shape.

12. The AFS injector (150) of claim 1, wherein each mixing chamber of the plurality of mixing chambers (214) is angled radially from the axis of the combustion liner (164).

13. 2. The AFS injector of claim 1, wherein the mixing element and the HP air injection element each include a mounting element configured to receive a fastener to couple the mixing element and the HP air injection element to a combustion liner.

14. 2. The AFS injector of claim 1, wherein each set of HP air jets is configured to draw LP air from a low pressure (LP) air source and direct the LP air along with the HP air to the inlet of each respective mixing chamber, the HP air source being in direct fluid communication with a compressor discharge of the GT system, and the LP air source being in fluid communication with a cooling passage defined along at least a portion of the combustion liner.

15. A combustor (100) for a gas turbine system (90), comprising: a combustor body (160) including a combustion liner (164); a plurality of axial fuel stage (AFS) injectors (150) directed toward the combustion liner (164), each AFS injector (150) comprising: A mixing element (210), a plurality of mixing chambers defined in the mixing element, each mixing chamber including an inlet and an outlet, each outlet configured to be in fluid communication with a combustion liner of the combustor; a pair of fuel injectors (230) defined in the sidewall (222) of each mixing chamber (214); a mixing element (210) comprising: a high-pressure (HP) air injection element (212) defining a set of HP air jets (240) spaced apart from the inlet (216) of each mixing chamber (214); and a fuel plenum (220) defined in the mixing element (210), the fuel plenum (220) configured to deliver fuel (114A, 114B) from a fuel source (116) to a respective pair of fuel injectors (230); a plurality of AFS injectors (150) including Equipped with each set of HP air jets (240) is configured to direct HP air (112) from an HP air source (154) to the inlets (216) of respective mixing chambers (214) into which fuel (114A, 114B) is injected by the set of fuel injectors (230); A combustor (100).

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