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A fuel injector (10) for an internal combustion engine (88) includes a centerbody (12) and a casing (14) disposed radially outward of the centerbody to define an annular mixing section (16) between the centerbody and the casing. The fuel injector also includes an air inlet (e.g., 18) of the mixing

A fuel injector (10) for an internal combustion engine (88) includes a centerbody (12) and a casing (14) disposed radially outward of the centerbody to define an annular mixing section (16) between the centerbody and the casing. The fuel injector also includes an air inlet (e.g., 18) of the mixing section for injecting a first portion (22) of combustion air into the mixing section. A fuel inlet (32) is disposed in the centerbody for injecting fuel (34) into the mixing section. A fuel conduit (48) disposed in the centerbody conducts the fuel to the fuel inlet and a valve (50) disposed in the fuel conduit selectively controls fuel injection into the mixing section. The valve may be positioned sufficiently close to the fuel inlet to provide the desired accurate timed injection. The injector also includes an outlet (19) of the mixing section for discharging a fuel/air mixture (60).

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What is claimed is: 1. A fuel injector for an internal combustion engine comprising: a centerbody; a first casing disposed radially outward of the centerbody to define an annular mixing section between the centerbody and the first casing; an axial air inlet at an upstream end of the mixing section

What is claimed is: 1. A fuel injector for an internal combustion engine comprising: a centerbody; a first casing disposed radially outward of the centerbody to define an annular mixing section between the centerbody and the first casing; an axial air inlet at an upstream end of the mixing section for axially injecting a first portion of combustion air into the mixing section; a radial air inlet disposed in the first casing for radially injecting a second portion of combustion air into the mixing section; a fuel inlet disposed in the centerbody downstream of the axial air inlet for injecting fuel into the mixing section; and a vortex generator disposed in the mixing section for producing axially extending vortices with the second portion of the combustion air radially injected into the mixing section to promote mixing of the injected fuel with the first and second portions of the injected combustion air to generate a fuel/air mixture at an outlet of the fuel injector. 2. The fuel injector of claim 1, wherein the fuel inlet is configured to inject the fuel with an axial velocity component directed upstream. 3. The fuel injector of claim 1, wherein the fuel inlet is angularly displaced with respect to the radial air inlet. 4. The fuel injector of claim 1, further comprising a second casing to define a plenum for receiving the second portion of the combustion air and for conducting the second portion of the combustion air to the radial air inlet. 5. The fuel injector of claim 1, further comprising a fuel conduit disposed in the centerbody for conducting the fuel to the fuel inlet. 6. The fuel injector of claim 5, further comprising a valve disposed in the fuel conduit for selectively controlling fuel injection into the mixing section. 7. The fuel injector of claim 6, wherein the valve is operable responsive to a sensed mass flow of the combustion air to achieve a desired constant equivalence ratio of a resulting fuel/air mixture generated during an injection cycle. 8. The fuel injector of claim 6, wherein the valve is operable responsive to a predetermined, time varying mass flow of the combustion air to achieve a desired constant equivalence ratio of a resulting fuel/air mixture generated during an injection cycle. 9. A method of controlling a fuel/air mixing operation of the fuel injector of claim 6 comprising controlling an opening position of the valve responsive to a time varying mass flow of the combustion air to provide a variable fuel amount delivered into the mixing section during a fuel injection cycle effective to maintain a desired equivalence ratio of the fuel/air mixture. 10. The fuel injector of claim 1, wherein an area ratio of the axial air inlet and the radial air inlet is configured to achieve a desired flow configuration and mixing effect. 11. The fuel injector of claim 1, wherein the radial inlet comprises a plurality of annularly spaced apart slots axially extending in at least a portion of the first casing. 12. The fuel injector of claim 11, wherein the vortex generator comprises a plurality of annularly spaced apart vanes formed in an outer surface of the centerbody. 13. The fuel injector of claim 12, wherein the vanes comprise curved lateral surfaces. 14. The fuel injector of claim 12, wherein the vanes extend along at least an axial portion of the centerbody and are directed radially outward from the centerbody at least partially into the mixing section. 15. The fuel injector of claim 14, wherein the vanes comprise a first plurality of peaked portions aligned with respective slots of the radial inlet so that the radially injected air is split by the peaked portions to generate respective counter-rotating vortices with the radially injected air. 16. The fuel injector of claim 15, wherein the vanes comprise a second plurality of peaked portions angularly displaced with respect to the slots of the radial air inlet. 17. The fuel injector of claim 16, wherein fuel inlets are disposed in the second plurality of peaked portions. 18. The fuel injector of claim 17, wherein the curved lateral surfaces of the vanes are configured to redirect the radially injected second portion of combustion air at the first plurality of peaked portions towards the fuel inlets disposed in the second plurality of peaked portions to enhance mixing of the combustion air with the injected fuel. 19. The fuel injector of claim 11, wherein the vortex generator comprises a plurality of annularly spaced apart vanes formed in an outer surface of the centerbody and extending along at least an axial portion of the centerbody and directed radially outward from the centerbody at least partially into the mixing section, the vanes being angularly displaced with respect to the slots of the radial air inlet. 20. The fuel injector of claim 19, wherein fuel inlets are disposed in peaked portions of the vanes. 21. The fuel injector of claim 19, wherein the vanes comprise curved lateral surfaces. 22. The fuel injector of claim 21, wherein the curved lateral surfaces of adjacent vanes define an axially extending trough therebetween, a center of the trough being angularly aligned with the slots of the radial air inlet effective to generate counter-rotating vortices with the second portion of the air injected at the radial air inlet and to redirect the radially injected air towards spaced apart fuel inlets disposed in peaked portions of the vanes. 23. The fuel injector of claim 1, wherein the vortex generator comprises a surface portion axially extending along the centerbody between spaced apart fuel inlets, the fuel inlets being angularly displaced with respect to the radial air inlet. 24. The fuel injector of claim 1, wherein the fuel comprises a gaseous fuel. 25. The fuel injector of claim 24, wherein the gaseous fuel is hydrogen, natural gas, syngas, or biogas. 26. The fuel injector of claim 1, wherein a premixed fuel/air mixture is provided to the axial and radial air inlets. 27. An internal combustion engine comprising the fuel injector of claim 1. 28. A fuel injector for an internal combustion engine comprising: a centerbody; a casing disposed radially outward of the centerbody to define an annular mixing section between the centerbody and the casing; an axial air inlet at an upstream end of the mixing section for axially injecting a first portion of combustion air into the mixing section; a radial air inlet disposed in the casing for radially injecting a second portion of combustion air into the mixing section; a fuel inlet disposed in the centerbody downstream of the axial air inlet for injecting fuel into the mixing section; a fuel conduit disposed in the centerbody for conducting the fuel to the fuel inlet; and a valve disposed in the fuel conduit for selectively controlling fuel injection into the mixing section, the valve being positioned sufficiently close to the fuel inlet to reduce a distance between the valve and fuel inlet. 29. The fuel injector of claim 28, wherein the valve comprises a magnetic valve. 30. The fuel injector of claim 28, wherein the valve comprises a piezoelectric valve. 31. The fuel injector of claim 28, further comprising a flashback detector disposed proximate the outlet for sensing a flashback condition and controlling an operation of the valve when a flashback condition is sensed. 32. The fuel injector of claim 28, wherein the valve is operable responsive to a sensed mass flow of the combustion air to achieve a desired constant equivalence ratio of a resulting fuel/air mixture generated during an injection cycle. 33. The fuel injector of claim 28, wherein the valve is operable responsive to a predetermined, time varying mass flow of the combustion air to achieve a desired constant equivalence ratio of a resulting fuel/air mixture generated during an injection cycle. 34. A fuel injector for an internal combustion engine comprising: a centerbody; a casing disposed radially outward of the centerbody to define an annular mixing section between the centerbody and the casing; an air inlet of the mixing section for injecting at least a first portion of combustion air into the mixing section; a fuel inlet disposed in the centerbody for injecting fuel into the mixing section; a fuel conduit for conducting the fuel to the fuel inlet; a valve disposed in the fuel conduit for selectively controlling fuel injection into the mixing section; and an outlet of the mixing section for discharging a fuel/air mixture. 35. The fuel injector of claim 34, wherein the air inlet compromises an axial air inlet at an upstream end of the mixing section for axially injecting the at least first portion of combustion air into the mixing section. 36. The fuel injector of claim 35, further comprising a radial air inlet disposed in the casing for radially injecting a second portion of combustion air into the mixing section. 37. The fuel injector of claim 34, wherein the air inlet comprises a radial air inlet disposed in the casing for radially injecting the at least first portion of combustion air into the mixing section. 38. The fuel injector of claim 37, further comprising a vortex generator disposed in the mixing section for producing longitudinal vortices within the first portion of the combustion air radially injected into the mixing section to promote mixing of the injected fuel with the first portion of the injected combustion air to generate the fuel/air mixture. 39. The fuel injector of claim 38, wherein the vortex generator comprises a plurality of annularly spaced apart vanes formed in an outer surface of the centerbody. 40. The fuel Injector of claim 34, wherein a premixed fuel/air mixture is provided to the air inlet. 41. The fuel injector of claim 34, wherein the valve is disposed in the centerbody sufficiently close to the fuel inlet to reduce a fuel volume delivered to the fuel inlet. 42. A method of controlling a fuel/air mixing operation of the fuel injector of claim 34 comprising controlling an opening position of the valve responsive to a time varying mass flow of the combustion air to provide a variable fuel amount delivered into the mixing section during a fuel injection cycle effective to maintain a desired equivalence ratio of the fuel/air mixture. 43. A method of controlling a fuel injector, comprising: receiving a time varying mass flow of combustion air into the fuel injector; and controlling an opening position of a fuel valve of the fuel injector responsive to the time varying mass flow of combustion air to provide a variable fuel amount delivered into a fuel/air mixing section of the fuel injector during a fuel injection cycle effective to maintain a desired equivalence ratio of a fuel/air mixture generated by the fuel injector. 44. The method of claim 43, further comprising sensing the time varying mass flow of the combustion air to control the opening position of a fuel valve. 45. The method of claim 43, further comprising predetermining expected values of the time varying mass flow of the combustion air to control the opening position of a fuel valve.