Combustion system featuring hybrid mixer unit to selectively mix air and fuel based on a fuel property

Abstract

A combustion system for a gas turbine engine. The system includes a hybrid mixer unit to mix air and a fuel blend. The unit includes a first mixing stage for premixed-based combustion and a second mixing stage for diffusion-based combustion. A fuel delivery subsystem is arranged to selectively control, based on a sensed thermochemical property of the fuel blend, a first portion of the fuel blend for the first stage and a second portion of the fuel blend for the second stage. This allows selectively adjusting the amount of fuel going to each stage based on the sensed property of the fuel blend. For example, a larger portion of the fuel blend would be mixed in the first stage for blends having a relatively low reactivity and a larger portion of the blend would be mixed in the second stage for blends having a relatively large reactivity. In one example embodiment, a modular cartridge including an array of the hybrid mixer units is manufactured by way of additive manufacturing.

Description

Docket No. 2024PF00140 COMBUSTION SYSTEM FEATURING HYBRID MIXER UNIT TO SELECTIVELY MIX AIR AND FUEL BASED ON A FUEL PROPERTY BACKGROUND

[0001] Disclosed embodiments relate to a combustion system for a gas turbine engine, and,more particularly, to a combustion system featuring a hybrid mixer unit structured to selectively mix air and fuel based on a property (e.g., a thermochemical property) of the fuel.

[0002] Hydrogen has substantially different properties than fuels that have been commonlyused in the context of a gas turbine engine, such as natural gas, etc. For example, the flame speed of hydrogen is substantially faster than that of natural gas, and therefore, fuel mixtures containing relatively high levels of hydrogen, up to pure hydrogen, are more susceptible to flashback and this can lead to undesirable issues in connection with combustor hardware subject to flashback. During flashback, flames can propagate upstream at speeds higher than the incoming gas flow and this can lead to thermal damage of hardware subject to such flames.

[0003] Moreover, in the context of the presently ongoing global energy transition, yet to befully realized, to greener forms of energy, it is not easy to predict with a high degree of certainty when hydrogen will be affordable and available in sufficiently large quantities to cost- effectively and consistently fuel gas turbines for power generation. Accordingly, there is a need of a flexible combustion system that can inhibit occurrence of flashback without increasing undesirable emissions and that can utilize a fuel blend involving, for example, natural gas and hydrogen regardless of the content of hydrogen and natural gas in the fuel blend. BRIEF SUMMARY

[0004] In one aspect, a combustion system for a gas turbine engine is provided. Thecombustion system includes a hybrid mixer unit arranged in a combustor of the combustion system to mix compressed air and a fuel blend of a first fuel and a second fuel. The hybrid mixer unit includes a first mixing stage conducive to premixed-based combustion and a second mixing stage conducive to diffusion-based combustion. A fuel delivery subsystem is configured to convey the fuel blend to the hybrid mixer unit. The fuel delivery subsystem includes a sensor arranged to sense a thermochemical property of the fuel blend to generate a signal indicative of the sensed thermochemical property of the fuel blend. A controller is responsive to the signal indicative of the sensed thermochemical property of the fuel blend to generate a control signal,Docket No. 2024PF00140 and a valve is responsive to the control signal from the controller to selectively control, based on the sensed thermochemical property of the fuel blend, a first portion of the fuel blend to convey to the first mixing stage and a second portion of the fuel blend to convey to the second mixing stage.

[0005] In another aspect, a computer-readable three-dimensional model of a modular cartridgefor a combustor of a combustion system in a gas turbine engine is provided. The model of the modular cartridge is processable in a processor configured to control an additive manufacturing technique to make the modular cartridge. The modular cartridge comprises an array of hybrid mixer units housed in the modular cartridge. Respective ones of the array of hybrid mixer units are interconnected to mix, in operation, compressed air and a fuel blend of a first fuel and a second fuel. Respective hybrid mixer units include a first mixing stage conducive to premixed- based combustion and a second mixing stage conducive to diffusion-based combustion. A fuel gallery is integrally constructed in the modular cartridge. The fuel gallery has a first fuel circuit arranged to convey to the first mixing stage a first portion of the fuel blend, and the fuel gallery further has a second fuel circuit arranged to convey to the second mixing stage a second portion of the fuel blend, where, based on a sensed thermochemical property of the fuel blend, respective sizes are determined of the first portion of the fuel blend and the second portion of the fuel blend to respectively convey to the first mixing stage and to the second mixing stage. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0006] To easily identify the discussion of any particular element or act, the most significantdigit or digits in a reference number refer to the figure number in which that element is first introduced.

[0007] FIG. 1 is in part a fragmentary sectional view of a gas turbine in accordance with oneembodiment.

[0008] FIG. 2 is a fragmentary, cutaway view of one example embodiment of an array ofdisclosed hybrid mixer units.

[0009] FIG. 3 is a fragmentary, cutaway view of another example embodiment of a hybridmixer unit.

[0010] FIG. 4 is a fragmentary isometric view of one example arrangement embodying severaldisclosed modular cartridges.Docket No. 2024PF00140

[0011] FIG. 5 is an isometric view illustrating further structural details in connection with adisclosed modular cartridge.

[0012] FIG. 6 is a flow sequence in connection with an additive manufacturing technique usedto make disclosed modular cartridges. DETAILED DESCRIPTION

[0013] The present inventors have recognized that there are mainly two basic approaches thathave been explored while attempting to solve the challenges of burning hydrogen in a gas turbine. One known approach, for example, starts from a conventional Dry Low Emission (DLE)-based combustion system, where the robustness of the DLE-based combustion system to inhibit flashback is somewhat improved by having a flow field in a premixer without recirculation zones or with minimal recirculation zones and by introducing purge air in the boundary layers to avoid or inhibit boundary layer flashback. A second known approach involves a diffusion flame combustion system. In this second approach, opposite to the first approach, fuel is not premixed in air before entering the combustor, but the fuel is mixed with air directly in the combustion chamber and hence little or no fuel is present upstream of the combustor, thus reducing the possibility of flashback. Combustion systems based on this second approach traditionally produce relatively higher levels of nitrogen oxides (NOx) compared to the DLE-based combustion system approach. This second approach has evolved by way of micro-mixing techniques that can involve a substantial number of injection locations (e.g., in the tens or even hundreds of injection locations) each having relatively smaller flames, thereby collectively reducing the time spent by the mixture in the hot regions of the flame and in turn reducing NOx production. This approach relies on a rapid and intense mixing of fuel jets in the cross-flowing air to minimize rich pockets in the flame (hot regions). However, known diffusion-based mixing (even when involving micro-mixing) still can produce relatively larger amounts of NOx than a comparable DLE-based combustion system, and therefore such known designs tend to be somewhat less competitive when the fuel is natural gas or with low levels of hydrogen blended with the natural gas.

[0014] Our disclosed embodiments feature a hybrid mixer unit that in a cost-effective andreliable manner preserves the respective advantages of the foregoing two approaches while inhibiting the individual challenges commonly associated with such approaches. That is, theDocket No. 2024PF00140 hybrid mixer unit in our disclosed embodiments has a first mixing stage conducive to premixed-based combustion and further has a second mixing stage conducive to diffusion- based combustion. This provides an opportunity to selectively adjust or vary the amount of fuel conveyed to each mixing stage depending on a property of the fuel or fuel blend being utilized, where, for example, a larger portion of the fuel would be mixed by way of the first mixing stage for fuel blends having a relatively lower reactivity (e.g., lower hydrogen content) and where a larger portion of the fuel would be mixed by way of the second mixing stage for fuel blends having a relatively larger reactivity (e.g., higher hydrogen content).

[0015] The present inventors have further recognized that traditional manufacturingtechniques may not be necessarily conducive to a cost-effective and / or realizable manufacturing of the hybrid mixer units featured in our disclosed combustion system. For example, traditional manufacturing techniques tend to fall somewhat short from consistently limiting manufacturing variability and may also fall short from cost-effectively and reliably producing the internal conduits (e.g., some of which involve miniaturized conduits) that are involved in the hybrid mixer units featured in the combustion system.

[0016] In view of this further recognition, in one non-limiting embodiment, the presentinventors further propose use of three-dimensional (3D) Printing / Additive Manufacturing (AM) technologies, such as laser sintering, selective laser melting (SLM), direct metal laser sintering (DMLS), electron beam sintering (EBS), electron beam melting (EBM), etc., that are conducive to cost-effectively making the disclosed hybrid mixer units. For readers desirous of general background information in connection with 3D Printing / Additive Manufacturing (AM) technologies, see, for example, textbook titled “Additive Manufacturing Technologies, 3DPrinting, Rapid Prototyping, and Direct Digital Manufacturing”, by Gibson I., Stucker B., andRosen D., 2010, published by Springer, and this textbook is herein incorporated by reference.

[0017] FIG. 1 is a fragmentary sectional view of a gas turbine 100 that in one non-limitingembodiment can provide, for example, a substantially inline air flow configuration, such as commonly used in aero-derivative and aero-engines. It will be understood that disclosed embodiments are not limited to the foregoing example categories of gas turbine engines. Gas turbine 100 includes a casing 104 that houses a compressor section 106 having a compressor outlet 108 that provides compressed air and further houses a combustion system 102, such as a combustor 110 that defines a combustion zone 112, where combustion occurs, such asDocket No. 2024PF00140 schematically represented by flames 113. Compressed air (schematically represented by arrows 114) from compressor outlet 108 is conveyed to combustion system 102.

[0018] In one example embodiment, a cowl 116 may be arranged to route compressed air 114into a modular cartridge 120 that houses an array of hybrid mixer units 200, 300 (FIG. 2 and FIG. 3 respectively) circumferentially distributed about a longitudinal axis 115 of the combustor. Hybrid mixer unit 200, 300 is a constituent unit of modular cartridge 120. It will be appreciated that cowl 116 is a structure that need not be utilized in every embodiment since, optionally, compressed air 114 could, by way of example, be directly conveyed from compressor outlet 108 to modular cartridge 120.

[0019] Hybrid mixer unit 200 is arranged in combustor 110 of combustion system 102 to mixcompressed air 114 and a fuel blend 122 of a first fuel and a second fuel. In one example embodiment, the first fuel of fuel blend 122 has a first reactivity index value and the second fuel of the fuel blend 122 has a second reactivity index value, where the second reactivity index value is larger compared to the first reactivity index value.

[0020] In one example embodiment, the first fuel is natural gas or a similar fuel and thesecond fuel is hydrogen or a similar fuel. In one example embodiment, the respective content percentages of the first fuel and the second fuel in fuel blend 122 can range from 0% or so to 100% or so regarding the content of hydrogen or ranges from 0% or so to 100% or so regarding the content of natural gas, where in each case a sum of the respective content percentages of the first fuel and the second fuel is equal to a total of 100% . In a general case, the first fuel could be any fuel (like natural gas or similar) with relatively low or no hydrogen content and the second fuel could be just hydrogen or any fuel mixture with relatively high hydrogen content.

[0021] As elaborated in greater detail below in the context of FIG. 2, hybrid mixer unit 200includes a first mixing stage (schematically represented by twin-headed arrow 210) conducive to premixed-based combustion and a second mixing stage (schematically represented by the shorter twin-headed arrow 240) conducive to diffusion-based combustion. Unless otherwise stated, the description in connection with hybrid mixer unit 200 (other than the specific reference numerals) equally applies to hybrid mixer unit 300 in the context of FIG. 3.

[0022] One basic tenet embodied in disclosed embodiments is the ability to selectivelydistribute fuel blend 122 between the first and the second mixing stages 210, 240 as a function of a thermochemical property of fuel blend 122. In one example embodiment, theDocket No. 2024PF00140 thermochemical property may be a reactivity index of fuel blend 122 or may be the fuel composition of fuel blend 122. The idea is to, for example, use mainly or exclusively the first mixing stage 210 (conducive to formation of premixed-based flames) for a low reactivity fuel blend and to use mainly or exclusively the second mixing stage 240 (conducive to formation of diffusion-based flames) for a high reactivity fuel blend. One goal behind hybrid mixer unit / s 200, 300 is to inhibit NOx emissions and flashback risks in an optimally balanced manner regardless of the respective contents of the first fuel and the second fuel in fuel blend 122.

[0023] In one example embodiment, combustion system 102 includes a fuel deliverysubsystem 140 (FIG. 1) configured to convey fuel blend 122 to modular cartridge 120 and thus to the array of hybrid mixer units 200, 300 housed in modular cartridge 120. In one example embodiment, fuel delivery subsystem 140 includes a sensor 142 arranged to sense the thermochemical property of the fuel blend to generate a signal indicative of the sensed thermochemical property of the fuel blend. As noted above, in one example embodiment, the sensed thermochemical property may be a reactivity index of fuel blend 122 or the fuel composition of fuel blend 122. In one example embodiment, fuel delivery subsystem 140 further includes a controller 146 responsive to the signal indicative of the sensed thermochemical property of fuel blend 122 to generate a control signal, and a valve 144, such as three-way valve, responsive to the control signal from controller 146 to selectively control, based on the sensed thermochemical property of the fuel blend, a first portion of fuel blend 122 to convey to the first mixing stage and a second portion of fuel blend 122 to convey to the second mixing stage. That is, to selectively control the quantity of the first portion of fuel blend 122 to convey to first mixing stage 210 and the quantity of the second portion of fuel blend 122 to convey to second mixing stage 240. In one example embodiment, controller 146 includes a comparator module 148 configured to compare the thermochemical property of the fuel blend relative to a predefined threshold of the thermochemical property. For example, when the sensed thermochemical property of the fuel blend is below the predefined threshold, then the first portion of the fuel blend conveyed to the first mixing stage is larger relative to the second portion of the fuel blend conveyed to the second mixing stage. By way of comparison, when the sensed thermochemical property of the fuel blend is above or equal to the predefined threshold, then the second portion of the fuel blend conveyed to the second mixing stage is larger relative to the first portion of the fuel blend conveyed to the first mixing stage.Docket No. 2024PF00140

[0024] FIG. 2 shows in part a fragmentary, cutaway view of one example embodiment of anarray of disclosed hybrid mixer units 200 that may be housed in modular cartridge 120. As noted above, each hybrid mixer unit 200 includes first mixing stage 210 conducive to premixed-based combustion and second mixing stage 240 conducive to diffusion-based combustion. In one example embodiment, first mixing stage 210 comprises a premixing tube 212 having an inlet 214 to receive compressed air 114, a vane 216 disposed in premixing tube 212 proximate the inlet 214 of premixing tube 212, where vane 216 has at least one fuel hole 217 to eject the first portion of the fuel blend into the flow of compressed air passing by vane 216, so that a resulting mixture of the first portion of fuel blend 122 and compressed air 114 flows toward an outlet 218 of premixing tube 212. In one example embodiment, second mixing stage 240 comprises at least one fuel hole 242 proximate the outlet 218 of premixing tube 212 to eject by way of cross-flow injection the second portion of the fuel blend into the flow of the mixture that flows towards the outlet 218 of premixing tube 212.

[0025] In one example embodiment, modular cartridge 120 comprises a monolithic structureincluding a fuel gallery 220, where fuel gallery 220 includes a first fuel circuit 222 fluidly connected to convey to the at least one fuel hole 217 in vane 216 the first portion of the fuel blend. Fuel gallery 220 further includes a second fuel circuit 224 fluidly connected to convey to the at least one fuel hole 242 proximate the outlet 218 of premixing tube 212 the second portion of the fuel blend. To avoid pedantic and unnecessary repetition, the description below is given in the context of just one of the example hybrid mixer units shown in FIG. 2, although the FIG. 2 shows a non-limiting example of seven hybrid mixer units 200.

[0026] FIG. 3 shows in part a fragmentary, cutaway view of one example embodiment of adisclosed hybrid mixer unit 300. As noted above, hybrid mixer unit 300 includes a first mixing stage (schematically represented by twin-headed arrow 310) conducive to premixed-based combustion and a second mixing stage (schematically represented by shorter twin-headed arrow 340) conducive to diffusion-based combustion. In one example embodiment, first mixing stage 310 comprises a premixing tube 312 having an inlet 314 to receive a flow of compressed air 114, a vane 316 disposed in premixing tube 312 proximate the inlet 314 of premixing tube 312, where vane 316 has at least one fuel hole 317 to eject the first portion of the fuel blend into the flow of compressed air passing by vane 316 so that a resulting mixture of the first portion of fuel blend 122 and compressed air 114 flows toward an outlet 318 of premixing tube 312. In this example embodiment, second mixing stage 340 comprises a centralDocket No. 2024PF00140 lance 341 having at least one fuel hole 342 proximate an outlet 344 of central lance 341 to eject, such as by way of cross-flow injection, the resulting mixture of the first portion of fuel blend 122 and compressed air 114 into the flow of the second portion of the fuel blend that flows from an inlet 344 of central lance 341 towards an outlet 346 of central lance 341.

[0027] FIG. 4 shows in part a fragmentary isometric view of one example embodiment ofdisclosed modular cartridges 120 (to reduce the possibility of visual cluttering just three modular cartridges are shown in FIG. 4) that individually house an array of hybrid mixer units, such as hybrid mixer units 300. It will be appreciated that in alternative embodiments, modular cartridge / s 120 can be tailored to accommodate hybrid mixer units 200.

[0028] It will be appreciated that that disclosed embodiments can be used in different classesof gas turbine engines, where our presently disclosed combustion system is scalable to meet the combustion-related requirements of any given gas turbine engine from the different classes of gas turbine engines. The scalability of the design can be implemented based on the number of hybrid mixer units (200 or 300) operatively interconnected in each modular cartridge 120. The scalability can be realized without having to change a footprint of the modular cartridges 120. That is, the same modular cartridge can be tailored for use in different classes of gas turbine engines.

[0029] FIG. 5 shows in part an exploded, isometric view illustrating certain details inconnection with a disclosed modular cartridge 120. In certain embodiments, a heat shield 402 (shown in exploded condition) may be used to thermally protect the mixing tubes 212 (or 312) of hybrid mixer units 200 (or 300). Additionally, cooling holes 404 may be provided to convey a cooling fluid, such as air, within modular cartridge 120. Respective inter-mixing tube volumes 406 defined between mixing tubes 212 (or 312) in the array of hybrid mixer units 200 (or 300) in modular cartridge 120 can be appropriately configured to provide a desired acoustic damping to the structures that define modular cartridge 120. That is, respective inter-mixing tube volumes 406 can be designed to provide during operation a cooling functionality together with acoustic damping functionality.

[0030] FIG. 6 is a flow sequence in connection with a disclosed technique for manufacturinga 3D object, such as modular cartridge 120. A computer-readable three-dimensional (3D) model 602, such as a computer aided design (CAD) model of the 3D object (i.e., modular cartridge 120) may be processed in a processor 604, where a slicing module 606 converts model 602 into a plurality of slice files (e.g., 2D data files) that define respective cross-Docket No. 2024PF00140 sectional layers of the 3D object. At least some of the plurality of slices define at least one void within at least some of the respective cross-sectional layers of the 3D object and collectively define the internal features, such as conduits, voids, structural arrangements, etc. to be constructed in the modular cartridge 120. Processor 604 may be configured to control an additive manufacturing system 608 to physically make the modular cartridge 120 with the structural and / or operational relationships, as described above in the context of Figs. 1 through 5.

[0031] In operation, disclosed embodiments offer a cost-effective, safe, and reliable mannerfor burning any fuel blends, such as without limitation involving hydrogen and natural gas (e.g., from pure natural gas to pure hydrogen) while inhibiting NOx emissions and reducing flashback risks.

[0032] In operation, disclosed embodiments offer continuous and variable staging betweenfirst and second diffusion stages (involving premixing and diffusion), as a function of a thermochemical property of the fuel blend, such as fuel composition and / or reactivity of the fuel blend. This feature permits mitigating various operational conditions that otherwise could develop in a combustion system, such as thermo-acoustic flame instability, lean blow out at lower loads, and further permits safe and rapid handling of transients (e.g., acceleration / deceleration, load shedding).

[0033] In operation, disclosed embodiments offer a substantially compact injector (e.g., in theform of modular cartridges) adaptable for various classes of gas turbine engines, such as without limitation, aero-derivative and aero-engines in which the combustor is parallel to the engine axis.

[0034] In operation, disclosed embodiments provide appropriately configured air and fuelpassages and cooling fluid passages fully integrated to provide appropriate connectivity and routing to the fluid-carrying conduits, openings in the modular cartridges.

[0035] Disclosed embodiments take advantage of additive manufacturing techniques thatpermit modular cartridges to have more injectors and further permit appropriately configuring the conduits in the modular cartridges, such as realizing length / diameter L / D ratio for such conduits within appropriate ranges.

[0036] In operation, disclosed embodiment offer user-friendly design scalability, such asbased on the number of hybrid mixer units operatively interconnected in each modular cartridge. The scalability of the design can be realized without having to change a footprint ofDocket No. 2024PF00140 the modular cartridges. That is, the same modular cartridge can be tailored for use in different classes of gas turbine engines without changing the physical dimensions of the modular cartridges.

[0037] In operation, disclosed embodiments permit user-friendly servicing, such in-situreplacements and serviceability of individual modular cartridges, without involving engine removal.

[0038] In operation, disclosed embodiments offer acoustic damping, such as included in thecooling passages of the modular cartridge.

[0039] Although at least one exemplary embodiment has been described in detail, thoseskilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the scope of the disclosure in its broadest form.

[0040] None of the description in the present application should be read as implying thatany particular element, step, act, or function is an essential element, which must be included in the claim scope. The scope of patented subject matter is defined only by the allowed claims. Moreover, none of these claims are intended to invoke a means plus function claim construction unless the exact words "means for" are followed by a participle.

Claims

Docket No. 2024PF00140 CLAIMS What is claimed is:

1. A combustion system for a gas turbine engine, comprising: a hybrid mixer unit arranged in a combustor of the combustion system to mix compressed air and a fuel blend of a first fuel and a second fuel, the hybrid mixer unit including a first mixing stage conducive to premixed-based combustion and a second mixing stage conducive to diffusion-based combustion; and a fuel delivery subsystem configured to convey the fuel blend to the hybrid mixer unit, the fuel delivery subsystem comprising: a sensor arranged to sense a thermochemical property of the fuel blend to generate a signal indicative of the sensed thermochemical property of the fuel blend; a controller responsive to the signal indicative of the sensed thermochemical property of the fuel blend to generate a control signal; and a valve responsive to the control signal from the controller to selectively control, based on the sensed thermochemical property of the fuel blend, a first portion of the fuel blend to convey to the first mixing stage and a second portion of the fuel blend to convey to the second mixing stage.

2. The combustion system of claim 1, wherein the first fuel of the fuel blend has a first reactivity index value, and the second fuel of the fuel blend has a second reactivity index value, and wherein the second reactivity index value is larger compared to the first reactivity index value.

3. The combustion system of claim 1 or 2, wherein the first fuel is natural gas, and the second fuel is hydrogen.

4. The combustion system of claim 3, wherein respective content percentages of the first fuel and the second fuel in the fuel blend range from 0% to 100% content of hydrogen or ranges from 0% to 100% content of natural gas, and wherein in each case a sum of the respective content percentages of the first fuel and the second fuel is equal to a total of 100%.Docket No. 2024PF00140 5. The combustion system of claim 1, wherein the controller includes a comparator module configured to compare the thermochemical property of the fuel blend relative to a predefined threshold of the thermochemical property.

6. The combustion system of claim 5, wherein, when the sensed thermochemical property of the fuel blend is below the predefined threshold, then the first portion of the fuel blend conveyed to the first mixing stage is larger relative to the second portion of the fuel blend conveyed to the second mixing stage.

7. The combustion system of claim 5, wherein, when the sensed thermochemical property of the fuel blend is above or equal to the predefined threshold, then the second portion of the fuel blend conveyed to the second mixing stage is larger relative to the first portion of the fuel blend conveyed to the first mixing stage.

8. The combustion system of any one of claims 1 through 7, wherein the hybrid mixer unit is a constituent unit in a modular cartridge that houses an array of the hybrid mixer units.

9. The combustion system of claim 8, wherein a plurality of the modular cartridges is circumferentially distributed about a longitudinal axis of the combustor.

10. A gas turbine engine from a plurality of different classes of gas turbine engines, the gas turbine engine including the combustion system of claim 8, wherein the combustion system is scalable to meet combustion-related requirements of the gas turbine engine from the plurality of different classes of gas turbine engines based on the number of hybrid mixer units operatively interconnected in the modular cartridge, and without having to change a footprint of the modular cartridge.

11. The combustion system of any one of claims 1 through 3, wherein the first mixing stage comprises a premixing tube having an inlet to receive a flow of the compressed air, a vane disposed in the premixing tube proximate the inlet, the vane having at least one fuel hole to inject the first portion of the fuel blend into a flow of the compressed air passing by the vane, wherein a resulting mixture of the first portion of the fuel blend and the compressed air flows towards an outlet of the premixing tube.Docket No. 2024PF00140 12. The combustion system of claim 11, wherein the second mixing stage comprises at least one fuel hole proximate the outlet of the premixing tube to inject, by way of cross-flow injection, the second portion of the fuel blend into the flow of the mixture that flows towards the outlet of the premixing tube.

13. The combustion system of claim 11, wherein the second mixing stage comprises a central lance having at least one fuel hole proximate an outlet of the central lance to inject, by way of cross-flow injection, the resulting mixture of the first portion of the fuel blend and air into a flow of the second portion of the fuel blend that flows from an inlet of the central lance towards the outlet of the central lance.

14. The combustion system of claim 1, wherein the thermochemical property of the fuel blend sensed by the sensor is selected from the group consisting of a reactivity index of the fuel blend, and a fuel composition of the fuel blend.

15. The combustion system of claim 8, wherein the modular cartridge comprises a monolithic structure including a fuel gallery defined in the monolithic structure of the modular cartridge, wherein the fuel gallery includes a first fuel circuit arranged to convey the first portion of the fuel blend to at least one fuel hole fluidly coupled to the first mixing stage.

16. The combustion system of claim 15, wherein the fuel gallery further includes a second fuel circuit fluidly arranged to convey the second portion of the fuel blend to at least one fuel hole fluidly coupled to the second mixing stage.

17. The combustion system of claim 16, wherein the second fuel circuit defines a conduit to convey the second portion of the fuel blend to the second mixing stage, wherein a respective length-to-diameter (l / d) ratio of the conduit is relatively lower compared to a respective to a length-to-diameter (l / d) ratio of the premixing tube of the first mixing stage.Docket No. 2024PF00140 18. A computer-readable three-dimensional model of a modular cartridge for a combustor of a combustion system in a gas turbine engine, wherein the model of the modular cartridge is processable in a processor configured to control an additive manufacturing technique to make the modular cartridge, the modular cartridge comprising: an array of hybrid mixer units housed in the modular cartridge; respective ones of the array of hybrid mixer units interconnected to mix in operation compressed air and a fuel blend of a first fuel and a second fuel, the respective ones of the array of hybrid mixer units including a first mixing stage conducive to premixed-based combustion and a second mixing stage conducive to diffusion-based combustion; and a fuel gallery integrally constructed in the modular cartridge, the fuel gallery having a first fuel circuit arranged to convey to the first mixing stage a first portion of the fuel blend, and wherein the fuel gallery has a second fuel circuit arranged to convey to the second mixing stage a second portion of the fuel blend, wherein, based on a sensed thermochemical property of the fuel blend, respective sizes are determined of the first portion of the fuel blend and the second portion of the fuel blend to respectively convey to the first mixing stage and to the second mixing stage.

19. The computer-readable three-dimensional model of claim 18, wherein the first fuel of the fuel blend has a first reactivity index value, and the second fuel of the fuel blend has a second reactivity index value, and wherein the second reactivity index value is larger compared to the first reactivity index value.

20. The computer-readable three-dimensional model of claim 19, wherein the first mixing stage comprises a premixing tube having an inlet to receive a flow of the compressed air, a vane disposed in the premixing tube proximate the inlet, the vane having at least one fuel hole to inject the first portion of the fuel blend into a flow of the compressed air passing by the vane, wherein a resulting mixture of the first portion of the fuel blend and the compressed air flows towards an outlet of the premixing tube.

21. The computer-readable three-dimensional model of claim 20, wherein the second mixing stage comprises at least one fuel hole proximate the outlet of the premixing tube to inject, by way of cross-flow injection, the second portion of the fuel blend into the flow of the mixture that flows towards the outlet of the premixing tube.Docket No. 2024PF00140 22. The combustion system of claim 20, wherein the second mixing stage comprises a central lance having at least one fuel hole proximate an outlet of the central lance to inject, by way of cross-flow injection, the resulting mixture of the first portion of the fuel blend and air into a flow of the second portion of the fuel blend that flows from an inlet of the central lance towards the outlet of the central lance 23. The computer-readable three-dimensional model of claim 21, wherein the modular cartridge comprises a monolithic structure including a fuel gallery defined in the monolithic structure of the modular cartridge, wherein the fuel gallery includes a first fuel circuit arranged to convey the first portion of the fuel blend to at least one fuel hole fluidly coupled to the first mixing stage, and wherein the fuel gallery further includes a second fuel circuit fluidly arranged to convey the second portion of the fuel blend to at least one fuel hole fluidly coupled to the second mixing stage.

24. The computer-readable three-dimensional model of claim 23, wherein the second fuel circuit defines a conduit to convey the second portion of the fuel blend to the second mixing stage, wherein a respective length-to-diameter (l / d) ratio of the conduit is relatively lower compared to a respective to a length-to-diameter (l / d) ratio of the premixing tube of the first mixing stage.

25. The computer-readable three-dimensional model of claim 18, wherein the computer- readable model is a computer aided design (CAD) model.

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