FLAME BACKFLAKE RESISTANT PREMIXED FUEL INJECTOR FOR A GAS TURBINE ENGINE

Abstract

A fuel injector for reducing flashback is described. In one embodiment, the fuel injector comprises an injector head with purge holes in a radial wall along a radial axis between a fuel injector assembly shaft and a plurality of vanes arranged circumferentially around the assembly shaft. The plurality of vanes may comprise fuel outlets connecting internal fuel passages to the gaps between the vanes. The introduction of these purge holes near the vane bases and the configuration and placement of the fuel outlets on the vanes and elsewhere in the fuel injector can alter the stoichiometry (e.g., the fuel-air ratio) within the fuel injector's premix passage to reduce flashback.Such fuel injectors can be used in the combustion chamber of a gas turbine engine.

Description

FLAME BACKFLAKE RESISTANT PREMIXED FUEL INJECTOR FOR A GAS TURBINE ENGINE FIELD OF INVENTION The modalities described in this description are generally directed to a fuel injector, and, more particularly, to a fuel injector with purge holes and fuel injection outlets that reduce the fuel injector's propensity for flame backfire. BACKGROUND OF THE INVENTION A lean premixed fuel injector is susceptible to flashback if specific criteria or operating conditions are met. Therefore, it is necessary to include features that reduce or eliminate the fuel injector's propensity for flashback. For example, U.S. Patent Publication No. 2013 / 0189632 describes a fuel nozzle with a nozzle collar that includes a number of air vanes. Purge holes are positioned through the air vanes to create a purge airflow intended to interrupt recirculation zones downstream from the fuel nozzle. The present description is directed to overcome one or more of the problems discovered by the inventors. Lecfrnn / eznz / B / YiAi Ref. 345498 SUMMARY OF THE INVENTION In one embodiment, an injector head for a fuel injector is described comprising: an injector body comprising a hyperbolic funnel-shaped injector portion rotating about an assembly axis, wherein, in a cross-section along the assembly axis, a wall of the injector portion passes from a radial axis, orthogonal to the assembly axis, to an axis parallel to the assembly axis; and a premix barrel surrounding the injector portion about the assembly axis and defining a premix passage between the premix barrel and the injector portion, wherein a radial portion of the wall of the injector portion along the radial axis comprises a plurality of purge holes connecting the premix passage to an injector cavity located inside the injector portion. BRIEF DESCRIPTION OF THE FIGURES The details of the modalities in this description, both in terms of their structure and operation, can be partly gleaned from the study of the accompanying figures, in which similar reference numbers refer to similar parts, and in which: Figure 1 illustrates a schematic diagram of a gas turbine engine, according to one modality; Figure 2 illustrates a perspective view of a Lecfrnn / eznz / B / YiAi fuel injector, according to a modality; Figure 3 illustrates a cross-sectional view of the fuel injector, according to one modality; Figure 4 illustrates a cross-sectional view of a fuel injector head, according to one modality; Figure 5 illustrates a cross-sectional view of a fuel injector head in Figure 4 in perspective, according to one modality; Figure 6 illustrates a cross-sectional view of the fuel injector head in Figures 4 and 5 at a shallower cutting depth, according to one embodiment; and Figure 7 illustrates a perspective view of a portion of a fuel injector head, according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION The detailed description below, in relation to the accompanying figures, is intended to be a description of several modalities and is not meant to represent the only modalities in which the description can be practiced. The detailed description includes specific details for the purpose of providing a complete understanding of the modalities. However, it will be evident to those skilled in the technique that the modalities of the LPCbnn / cznz / B / YiAi invention can be practiced without these specific details. In some cases, well-known structures and components are shown in a simplified form for the sake of brevity. For clarity and ease of explanation, some surfaces and details may be omitted from this description and figures. In addition, references to upstream and downstream in this description are relative to the flow direction of the primary gas (e.g., air) used in the combustion process, unless otherwise specified. Upstream refers to a position closer to the primary gas source or a direction toward the primary gas source, and downstream refers to a position farther from the primary gas source or a direction away from the primary gas source. Figure 1 illustrates a schematic diagram of a gas turbine engine 100, according to one embodiment. The gas turbine engine 100 comprises a shaft 102 with a central longitudinal axis L. A number of other components of the gas turbine engine 100 are concentric with the longitudinal axis L, and all references in this description to the radial, axial, and circumferential directions are relative to the longitudinal axis L. Lecfrnn / eznz / B / YiAi radial may refer to any axis or direction that radiates outward from the longitudinal axis L at an angle substantially orthogonal to the longitudinal axis L, such as the radial axis R in Figure 1. As used in the present description, the term axial will refer to any axis or direction that is substantially parallel to the longitudinal axis L. In one embodiment, the gas turbine engine 100 comprises, from an upstream end to a downstream end, an inlet 110, a compressor 120, a combustion chamber 130, a turbine 140, and an exhaust outlet 150. In addition, the downstream end of the gas turbine engine 100 may comprise a power output coupling 104. One or more, potentially including all, of these components of the gas turbine engine 100 may be made of stainless steel and / or durable, high-temperature materials known as superalloys. A superalloy is an alloy that exhibits excellent mechanical strength and creep resistance at high temperatures, good surface stability, and resistance to corrosion and oxidation. Examples of superalloys include, without limitation, Hastelloy, Inconel, Waspaloy, Rene alloys, Haynes alloys, Incoloy, MP98T, TMS alloys, and CMSX single-crystal alloys. Inlet 110 can channel a working fluid F (for example, a gas, such as air) in a path of Lecfrnn / eznz / B / YiAi annular flow 112 around the longitudinal axis L. The working fluid F flows through the inlet 110 into the compressor 120. Although it is illustrated that the working fluid F flows into the inlet 110 from a particular direction and at an angle that is substantially orthogonal to the longitudinal axis L, it should be understood that the inlet 110 can be configured to receive the working fluid F from any direction and at any angle that is suitable for the particular application of the gas turbine engine 100. The compressor 120 may comprise a series of compressor rotor assemblies 122 and stator assemblies 124. Each compressor rotor assembly 122 may comprise a rotor disk circumferentially occupied with a plurality of rotor blades. The rotor blades on one rotor disk are separated, along the axial axis, from the rotor blades on an adjacent disk by a stator assembly 124. The compressor 120 compresses the working fluid F through a series of stages corresponding to each compressor rotor assembly 122. The compressed working fluid F then flows from the compressor 120 into the combustion chamber 130. The combustion chamber 130 may comprise a combustion chamber housing 132 that houses one or more, and generally a plurality of, fuel injectors 134. In an embodiment with a plurality of injectors of Lecfrnn / eznz / B / YiAi Fuel 134, the fuel injectors 134 can be arranged circumferentially around the longitudinal axis L within the combustion chamber housing 132 at equidistant intervals. The combustion chamber housing 132 diffuses the working fluid F, and the fuel injector(s) 134 inject(s) fuel into the working fluid F. This injected fuel ignites to produce a combustion reaction in one or more combustion chambers 136. The fuel-combustion gas mixture drives the turbine 140. The turbine 140 may comprise one or more turbine rotor assemblies 142. As in the compressor 120, each turbine rotor assembly 142 may correspond to one of a series of stages. The turbine 140 extracts energy from the combustion gas-fuel mixture as it passes through each stage of one or more turbine rotor assemblies 142. The energy extracted by the turbine 140 may be transferred (for example, to an external system) through the power output coupling 104. The exhaust E from the turbine 140 can flow to the exhaust outlet 150. The exhaust outlet 150 can comprise an exhaust diffuser 152, which diffuses the exhaust E, and an exhaust manifold 154 that collects, redirects, and emits the exhaust E. It should be understood that the exhaust E, emitted by the exhaust manifold 154 may be further processed, for example, to reduce harmful emissions, recover heat, and / or similar purposes. In addition, while the exhaust E is illustrated as flowing out of the exhaust outlet 150 in a specific direction and at an angle that is substantially orthogonal to the longitudinal axis L, it should be understood that the exhaust outlet 150 may be configured to emit the exhaust E in any direction and at any angle that is suitable for the particular application of the gas turbine engine 100. Figure 2 illustrates a perspective view of a fuel injector 134, and Figure 3 illustrates a cross-sectional view of the same fuel injector 134, according to one embodiment. In the illustrated embodiment, each fuel injector 134 comprises a flange assembly 210, a distribution block 220, fuel lines 230, and an injector head 240, assembled along an assembly axis A. In embodiments in which the combustion chamber 130 comprises a plurality of fuel injectors 134, each of the plurality of fuel injectors 134 may be identical in structure. The flange assembly 210 may comprise a flange 212, a main fuel connector 214, a pilot fuel connector 216, and one or more handles 218. The flange 212 may be a cylindrical disc comprising openings for attaching the fuel injector 134 to the chamber housing. Combustion Lecfrnn / eznz / B / YiAi 130. The main fuel connector 214 and the pilot fuel connector 216 can provide inlets for the introduction of dual fuel sources to separate and distinguish the main and pilot fuel circuits, respectively. As illustrated, the center of the flange 212, through which the primary fuel connector 214 extends, can be offset from the assembly axis A. The distribution block 220 may extend axially downstream from the flange 212. The flange 212 and the distribution block 220 may be formed from a single integral piece of material, or they may be formed as separate pieces of material joined by any known means. The distribution block 220 acts as a manifold for one or more fuel circuits that distribute fuel flow through multiple fuel lines 230. The fuel lines 230 may comprise a tube stem 232, a first main tube 234, a second main tube 236, and a secondary tube 238. The first main tube 234 and the second main tube 236, which may be parallel to each other and to the assembly axis A, may form part of a first main fuel circuit. The secondary tube 238 may extend between the distribution block 220 and the injector head 230 at an angle to the assembly axis A, the first main tube Lecfrnn / eznz / B / YiAi 234, and the second main pipe 236, and form part of the first main fuel circuit or a second main fuel circuit. In one embodiment, the secondary pipe 238 forms part of the first main fuel circuit with the first main pipe 234 and the second main pipe 236. In addition, the secondary pipe 238 can act as a support pipe for the injector head 240 to prevent deflection of the injector head 240. The injector head 240 can be connected to the fuel lines 230 via their respective connectors, and may comprise an injector body 242, a premix barrel 244, and an outer cap 246. The connectors from the fuel lines 230 to the injector head 240 can be configured to link the fluid passages through the tube stem 232, the first main tube 234, the second main tube 236, and the secondary tube 238 to the passages in the injector body 242. In addition, the outer cap 246 may comprise one or more openings that allow the discharge gas (e.g., air) from the compressor 120 to enter the injector body 242. The 134 fuel injector may comprise a plurality of internal passages through these, including one or more main fuel circuits that Lecfrnn / eznz / B / YiAi are in fluid communication with the main fuel connector 214 and a pilot fuel circuit that is in fluid communication with the pilot fuel connector 216. Together, these passages can form a dual fuel supply system to receive main fuel and pilot fuel at the flange assembly 210 and distribute the main fuel and pilot fuel through the injector head 240 into a premix passage 248 illustrated in Figure 3. As illustrated in Figure 3, the primary fuel connector 214 can provide fluid communication to at least two branch passages 222 and 224 through the distribution block 220. Passage 222 can provide fluid communication through the first main tube 234 and / or the second main tube 236 to the injector head 240, and passage 224 can provide fluid communication through the secondary tube 238, as part of the main fuel circuit. Additionally, the pilot fuel connector 216 can provide fluid communication to a passage through a pilot fuel tube 233 that extends through the stem of tube 232, which extends through the flange 212 to the injector head 240, as part of the pilot fuel circuit. The pilot fuel tube 233 can be shaped as a hollow cylinder through a stem of Lecfrnn / eznz / B / YiAi solid tube 232. The main fuel circuit and pilot fuel circuit provide dual fuel paths through the fuel injector 134 to various outlets in the injector head 240. Figure 4 illustrates a cross-sectional view of the 240 injector head, according to one modality. As illustrated, the injector head 240 may comprise a first portion 410, a second portion 420, a pilot tube 430, a center portion 440, an injector portion 450, a plurality of vanes 460, and a barrel 470. The injector body 242 comprises the first portion 410, the second portion 420, the pilot tube 430, the center portion 440 coaxial around the pilot tube 430, and the injector portion 450 coaxial around the center portion 440. The premix barrel 244 comprises the plurality of vanes 460 and the barrel 470. While the premix barrel 244 is illustrated with twelve vanes 460, the premix barrel 244 may comprise any suitable number of vanes 460. The outer cap 246 may be a cap in the shape of dome that connects and extends upstream from the upstream end of the first body 410.These various portions can be formed as separate pieces and fastened together in any known way (e.g., metallurgical joining, such as by welding or brazing; fasteners, such as screws or bolts; etc.). Alternatively, Lecfrnn / eznz / B / YiAi any subset, including all, of the described portions can be formed as a single integrated piece. In one embodiment, the main fuel circuit, which may comprise passages through the first main tube 234, the second main tube 236, and the secondary tube 238, provides fluid communication from the main fuel connector 214 to an annular cavity 412 that extends circumferentially around the assembly axis A within the first portion 410. The annular main fuel cavity 412 is in fluid communication with an annular main fuel gallery 414, which also extends circumferentially around the assembly axis A, through an annular perforated plate 416 between the main fuel cavity 412 and the main fuel gallery 414. The perforations in the perforated plate 146 may be configured in size, shape, spacing, and / or density to restrict fluid flow and dampen the oscillation response of the combustion chamber 130. The main fuel gallery 414 can be in fluid communication with a plurality of first main fuel passages 422 through the second portion 420. In turn, each first main fuel passage 422 can be in fluid communication with a respective second main fuel passage 462 in a Lecfrnn / eznz / B / YiAi of the plurality of blades 460. Each of these blades 460 may comprise one or more main fuel outlets 464 from its respective second main fuel passage 462 to an exterior of the blade 460, so as to be in fluid communication with the premix passage 248. Combinations of each first main fuel passage 422 with a respective second main fuel passage 462 form a plurality of axial main fuel passages, circumferentially separated about the assembly axis A, each providing a flow path from the main fuel gallery 414 through one of the plurality of blades 460 and out of the main fuel outlet(s) of that blade 464 to the premix passage 248. In one embodiment, each blade 460 comprises a set of five main fuel outlets 464 arranged along an axial line with each other. Each main fuel outlet 464 can extend transversely through a wall of the respective blade 460. The main fuel outlets 464 can provide a flow path across an outer surface of each blade 460 between adjacent blades 460, such that the main fuel flows out of the main fuel outlets 464 into the spaces between adjacent blades 460. In other words, each fuel outlet The main vane 464 can be connected to the premix passage 248 on one side of its respective vane 460, which is oriented towards a gap between the respective vane 460 and an adjacent vane 460. Each vane 460 can be wedge-shaped with a truncated tip configured to direct gas (e.g., air) towards the premix passage 248. However, the shape of the vanes 460 is not limited to this. In general, the vanes 460 can be shaped to generate eddies to promote the formation of recirculation zones of the fuel and gas mixture in the combustion chamber 136. The main fuel outlets 464 on a given blade 460 may be spaced at equidistant intervals along an axial line, and the main fuel outlets 464 at each end of the axial line of main fuel outlets 464 may be separated from an axial end of the blade 460 by a distance. These intervals and distances may be selected according to a combustion chamber oscillation response 130. In one embodiment, each main fuel outlet 464 is circular in profile and identical. However, the main fuel outlets 464 may have non-circular profiles (elliptical, rectangular, triangular, irregular polygonal, etc.) and / or may differ from each other in size, shape, and / or relative spacing. Lecfrnn / eznz / B / YiAi In one embodiment, the pilot fuel circuit, which may comprise a passage through the pilot fuel tube 233 in the tube stem 232, provides fluid communication from the pilot fuel connector 216 to an annular pilot fuel gallery 441 that extends circumferentially around the assembly axis A in the central portion 440. The pilot fuel gallery 441 may be in fluid communication with one or more axial pilot fuel distribution passages 442, which may be configured in size, spacing, shape, and / or density to dampen the oscillation response of the combustion chamber 130. In turn, each pilot fuel distribution passage 442 may be in fluid communication with a central annular pilot fuel cavity 443 that extends circumferentially around the assembly axis A and surrounds the pilot tube 430.In turn, the central pilot fuel cavity 443 may be in fluid communication with one or more axial pilot block passages 444. In turn, each pilot block passage 444 may be in fluid communication with a pilot premix passage 445 that is open to the premix passage 248 at the downstream end. The downstream tip of the central portion 440 may further comprise one or more radial tip passages 446. Lecfrnn / eznz / B / YiAi provide fluid communication between the pilot premix passage 445 and an injector cavity 452 within the injector portion 450. In one embodiment, the first portion 410 comprises an annular feed passage 451 extending circumferentially around the assembly shaft A and receiving a gas (for example, air), at its upstream end, from the compressor 120 through opening(s) in the outer cover 246. The feed passage 451 may be in fluid communication, at a downstream end, with an annular injector cavity 452 in the injector portion 450 that extends circumferentially around the assembly shaft A and surrounds the center portion 440. In turn, the injector cavity 452 may be in fluid communication with one or more axial gas passages 453 in the injector portion 450. In turn, each gas passage 453 may be in fluid communication with an annular tip cavity 454 in the injector portion 450 that extends circumferentially around the assembly shaft A and surrounds the downstream tip of the center portion 440.In turn, the tip cavity 454 may be in fluid communication with an injector opening 455 at the downstream end of the injector portion 450. The combination of the feed passage 451, the injector cavity 452, the axial gas passage(s) 453, the tip cavity 454, and the injector opening 455 provides a. Lecfrnn / eznz / B / YiAi flow path for gas (e.g., air) through injector portion 450 around assembly axis A. In addition, the radial tip passage(s) 446 through the downstream tip of the center portion 440 provides a flow path for gas from the injector cavity 452 to the pilot premix passage 445 of the center portion 440. In one embodiment, the injector portion 450 may be shaped like a hyperbolic funnel rotating about the assembly axis A. Therefore, as illustrated in Figure 4, at the upstream end of the injector portion 450, the walls of the injector portion 450 may transition from a radial to an axial direction relative to the assembly axis A. Consequently, the injector portion 450 may comprise a radial wall 456 that defines a portion of the premix passage 248. One or more purge holes 457 may be formed through the radial wall 456 to provide fluid communication between the premix passage 248 and the injector cavity 452. Figure 5 illustrates a perspective cross-sectional view of the injector head 240, according to one embodiment. As illustrated, the injector portion 450 may comprise a plurality of purge holes 457 through the radial wall 456. Purge holes 457A, 457B, 457C, and 457D are visible in Figure 5. LPCbnn / cznz / B / YiAi purge 457 can be arranged circumferentially around the assembly axis A at equidistant intervals from each other. In one embodiment, a bleed hole 457 is located in the radial wall 456, along a radial axis between the assembly axis A and each blade 460, at or near the base of the trailing edge of the blade 460. Although a specific number and arrangement of bleed holes 457 (for example, twelve bleed holes 457) are illustrated in Figure 5, the radial wall 456 may comprise any number and / or arrangement of bleed holes 457. In one embodiment, there is a one-to-one correspondence between the bleed holes 457 and the blades 460, such that each bleed hole 457 corresponds to exactly one blade 460, and each blade 460 corresponds to exactly one bleed hole 457. Figure 6 illustrates a cross-sectional view of the injector head 240 at a shallower cut depth than in Figure 4, according to one embodiment. As illustrated in Figure 6, each bleed hole 457 provides fluid communication through the radial wall 456 of the injector portion 450 to allow gas (e.g., air) to flow between the injector cavity 452 and an upstream portion of the premix passage 248. Notably, in the illustrated embodiment, there are no bleed holes at the trailing edges of the vanes 460. Such bleed holes could adversely affect the Lecfrnn / eznz / B / YiAi stoichiometry in the premix passage 248 and increase flame flashback. Figure 7 illustrates a perspective view of a portion of the injector head 240, according to one embodiment. As illustrated, a plurality of truncated wedge-shaped vanes 460 are arranged circumferentially around the premix barrel 244 at equidistant intervals, with the trailing edge of each vane 460 facing the premix passage 248. One or more, including potentially all, of the vanes 460 may comprise a set of axially aligned main fuel outlets 464. For example, in the illustrated embodiment, each set of main fuel outlets 464 on each vane 460 consists of five main fuel outlets 464. Therefore, in the illustrated fuel injector 134 with twelve vanes 460, there are a total of sixty main fuel outlets 464.In one embodiment, the fuel injector 134 may contain only the main fuel outlets 464 in the vanes 460 (e.g., sixty main fuel outlets), without any other outlets for the main fuel. Each main fuel outlet 464 may supply main fuel from the main fuel circuit to the gaps between the vanes 460, which are in open fluid communication with the premix passage 248. The main fuel outlets 464 can be sized to maintain an adequate fuel system pressure drop at the fuel injector 134. In particular, the purge holes 457 through the radial wall 456 of the injector portion 450 are also visible in Figure 7 through the gaps between the vanes 460. Industrial Applicability Gas turbine engines are used in a variety of industrial applications. Examples of such applications include the petroleum and fuel industry (e.g., for the transmission, gathering, storage, extraction, and / or lifting of oil and natural gas), the power generation and cogeneration industries, the aerospace industry, other transportation industries, and similar industries. In one embodiment, during the operation of the gas turbine engine 100, the compressed working fluid F (e.g., air) from the compressor 120 enters the premix passage 248 through the gaps between the blades 460. This working fluid F is mixed with the main fuel discharged from the main fuel outlets 464. The premix passage 248 discharges this fuel-gas (e.g., fuel-air) mixture into a combustion chamber 136 for combustion. The configuration and position of the outputs ofThe main fuel injector 464 and the purge holes 457 in the fuel injector 134 alter the stoichiometry (e.g., the fuel-to-air ratio) in the premix passage 248, thereby reducing flame propagation to the vanes 460 and flame flashback. Specifically, regions of the premix passage 248 near the trailing edges of the vanes 460 are prone to recirculation and a fuel-gas mixture that leads to a reaction. The purge holes 457 in or near the vane bases 460 eliminate stagnant recirculation zones and introduce gas (e.g., air) that manipulates the gas side of the local gas-fuel ratio to reduce the gas-fuel mixture within the combustion chamber 136 along the wall of the injector portion 450.Furthermore, the size, arrangement, and position of the main fuel outlets 464 manipulate the fuel side of the local fuel-to-gas ratio to achieve proper local stegimetry. These effects reduce the reaction in these regions of the premix passage 248 and thus reduce the propensity for flame flashback in these regions. In other words, the described features decrease the flammability of the fuel-gas mixture along the outer surface of the injector portion 450, and therefore reduce the propensity for a flame to flash back. Lecfrnn / eznz / B / YiAi displace along this outer surface the 460 vanes and the flame backlash. In one embodiment, to improve these effects, the 460 vanes do not comprise any purge holes along their trailing edges. It should be understood that the benefits and advantages described above may refer to one modality or to several modalities. The aspects described in relation to one modality are intended to be applicable to the other modalities. Any explanation relating to one modality applies to similar characteristics of the other modalities, and elements of multiple modalities may be combined to form other modalities. The modalities are not limited to those that solve any or all of the problems indicated or those that have any or all of the benefits and advantages indicated. The foregoing detailed description is merely illustrative and is not intended to limit the invention or its applications and uses. The described embodiments are not limited to use with a particular type of gas turbine engine or combustion chamber. Therefore, although the present embodiments are, for ease of explanation, represented and described as implemented in a particular fuel injector for a particular combustion chamber in a gas turbine engine, Lecfrnn / eznz / B / YiAi, a particular gas turbine, will be appreciated as being applicable to various other types of fuel injectors (e.g., dual-fuel injectors, such as Dry Low Emission (DLE) and Lean Direct Injection (LDI) dual-fuel (DF) systems), combustion chambers, gas turbine engines, and / or turbomachinery, and in other systems and environments. Furthermore, there is no intention to be limited by any theory presented in any preceding section. It is further understood that illustrations may include exaggerated dimensions and graphical representations to better illustrate the referenced elements shown, and are not considered limiting unless expressly stated as such. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. An injector head for a fuel injector, characterized in that it comprises: an injector body comprising a hyperbolic funnel-shaped injector portion rotating about an assembly axis, wherein, in a cross-section along the assembly axis, a wall of the injector portion passes from a radial axis, which is orthogonal to the assembly axis, to an axis parallel to the assembly axis; and a premix barrel surrounding the injector portion about the assembly axis and defining a premix passage between the premix barrel and the injector portion, wherein a radial portion of the wall of the injector portion along the radial axis comprises a plurality of purge holes connecting the premix passage to an injector cavity, which is internal to the injector portion.

2. The injector head according to claim 1, characterized in that the premix barrel comprises a plurality of vanes spaced at equidistant intervals circumferentially around at least a portion of the injector portion and around the assembly axis, wherein each of the plurality of vanes comprises a fuel passage in an inner portion of the vane and one or more fuel outlets connecting the fuel passage to the premix passage.

3. The injector head according to claim 2, characterized in that for each of the plurality of vanes, each of the one or more fuel outlets is connected to the premix passage on one side of the vane that is oriented towards a gap between the vane and an adjacent vane.

4. The injector head according to claim 2, characterized in that the one or more fuel outlets in the plurality of vanes are the only outlets for the main fuel in the injector head, and wherein none of the plurality of vanes comprises any purge hole.

5. The injector head according to claim 2, characterized in that each of the plurality of purge holes is placed in the radial portion of the wall of the injector portion along a radial axis between the assembly axis and one of the plurality of vanes.

6. The injector head according to claim 2 of Lecfrnn / eznz / B / YiAi, characterized in that the injector body further comprises, for each of the plurality of vanes, a fuel passage connecting the fuel passage in the vane to a main fuel gallery in the injector body.

7. The injector head according to claim 1, characterized in that the injector body further comprises: one or more feed passages connecting the injector cavity to an exterior of the injector body that is upstream of the injector cavity; and a downstream axial flow path from one or more feed passages through the injector cavity to an opening at a downstream end of the injector portion.

8. The injector head according to claim 1, characterized in that the injector body further comprises a central portion that is coaxial to the injector portion and within the injector cavity, wherein the central portion comprises a downstream axial flow path from an upstream end of the central portion to an opening at a downstream end of the central portion.

9. The injector head according to claim 8, characterized in that a tip of the Lecfrnn / eznz / B / YiAi central portion at the downstream end of the central portion comprises one or more radial tip passages radially connecting the injector cavity to the axial flow path downstream of the central portion.

10. The injector head according to claim 8, characterized in that the injector body further comprises a pilot tube that is coaxial to the central portion.

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