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A fuel injector includes an annular main fuel nozzle received within an annular nozzle housing, a main nozzle fuel circuit having at least one annular leg, and a pilot nozzle fuel circuit. Spray orifices of the leg extend through the fuel nozzle and spray wells through the housing are aligned with t

A fuel injector includes an annular main fuel nozzle received within an annular nozzle housing, a main nozzle fuel circuit having at least one annular leg, and a pilot nozzle fuel circuit. Spray orifices of the leg extend through the fuel nozzle and spray wells through the housing are aligned with the orifices. The nozzle is designed to generate sufficient static pressure differentials between at least two different ones of the spray wells to purge the main nozzle fuel circuit. Spray well portions may be asymmetrically flared out with respect to a spray well centerline in different local streamwise directions. Some of the spray well portions may be asymmetrically flared out in a local upstream direction and others in a local downstream direction. The local streamwise direction may have an axial component parallel to a nozzle axis about which the annular nozzle housing is circumscribed and a circumferential component around the nozzle housing.

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1. A fuel injector comprising:an annular nozzle housing, an annular fuel nozzle within the housing, the annular fuel nozzle including at least one main nozzle fuel circuit having at least one annular leg and a pilot nozzle fuel circuit, spray orifices extending radially away from the annular leg thr

1. A fuel injector comprising:an annular nozzle housing, an annular fuel nozzle within the housing, the annular fuel nozzle including at least one main nozzle fuel circuit having at least one annular leg and a pilot nozzle fuel circuit, spray orifices extending radially away from the annular leg through the annular fuel nozzle, spray wells extending radially through the nozzle housing and aligned with the spray orifices, and differential pressure means for generating sufficient static pressure differentials between at least two different ones of the spray wells to purge the main nozzle fuel circuit. 2. The fuel injector as claimed in claim 1, wherein the differential pressure means includes the spray wells having well portions asymmetrically flared out with respect to a spray well centerline in a local streamwise direction.3. The fuel injector as claimed in claim 2, wherein the local streamwise direction is an upstream direction.4. The fuel injector as claimed in claim 2, wherein the local streamwise direction is a downstream direction.5. The fuel injector as claimed in claim 2, further comprising a first plurality of the spray wells having the well portions asymmetrically flared out with respect to the spray well centerline in a local upstream direction and a second plurality of the spray wells having the well portions asymmetrically flared out with respect to the spray well centerline in a local downstream direction.6. The fuel injector as claimed in claim 2, wherein the local streamwise direction has axial component parallel to a nozzle axis about which the annular nozzle housing is circumscribed and a circumferential component around the nozzle housing.7. The fuel injector as claimed in claim 2 further comprising each of the spray wells having a radially extending wall portion substantially parallel to the spray well centerline and a well portion asymmetrically flared out from the spray well centerline and extending away from the radially extending wall portion.8. The fuel injector as claimed in claim 7, wherein the local streamwise direction is an upstream direction.9. The fuel injector as claimed in claim 7, wherein the local streamwise direction is a downstream direction.10. The fuel injector as claimed in claim 7, further comprising a first plurality of the spray wells having the well portions asymmetrically flared out with respect to the spray well centerline in a local upstream direction and a second plurality of the spray wells having the well portions asymmetrically flared out with respect to the spray well centerline in a local downstream direction.11. The fuel injector as claimed in claim 10, wherein the local streamwise direction has axial component parallel to a nozzle axis about which the annular nozzle housing is circumscribed and a circumferential component around the nozzle housing.12. The fuel injector as claimed in claim 10, further comprising a lip around a portion of each of the spray wells along the asymmetrically flared out well portions.13. The fuel injector as claimed in claim 1, further comprising the spray wells having at least two types of the well portions chosen from a group consisting of symmetrically flared out well portions, asymmetrically upstream flared out well portions flared outwardly with respect to the spray well centerline in a local upstream direction, and asymmetrically downstream flared out well portions flared outwardly with respect to the spray well centerline in a local downstream direction.14. The fuel injector as claimed in claim 13, further comprising adjacent ones of the spray orifices in the annular leg are aligned with spray wells having different types of the well portions chosen from the group.15. The fuel injector as claimed in claim 1, further comprising:the spray wells being symmetric spray wells, upstream and downstream annular rows of the symmetric spray wells, and the differential pressure means including an annular row of radial flow swirlers radially outwardly disposed around the upstream annular row of the spray wells. 16. A fuel injector comprising:an annular nozzle housing, an annular fuel nozzle received within the housing, the annular fuel nozzle including at least one main nozzle fuel circuit having first and second fuel circuit branches and a pilot nozzle fuel circuit, each of the first and second fuel circuit branches having clockwise and counterclockwise extending annular legs, spray orifices extending radially away from the annular legs through the annular fuel nozzle, spray wells extending radially through the nozzle housing and each of the spray wells is aligned with one of the spray orifices, and differential pressure means for generating sufficient static pressure differentials between at least two different ones of the spray wells to purge the main nozzle fuel circuit. 17. The fuel injector as claimed in claim 16, wherein the differential pressure means includes the spray wells having well portions asymmetrically flared out with respect to a spray well centerline in a local streamwise direction.18. The fuel injector as claimed in claim 17, wherein the local streamwise direction is an upstream direction.19. The fuel injector as claimed in claim 17, wherein the local streamwise direction is a downstream direction.20. The fuel injector as claimed in claim 17, further comprising a first plurality of the spray wells having the well portions asymmetrically flared out with respect to the spray well centerline in a local upstream direction and a second plurality of the spray wells having the well portions asymmetrically flared out with respect to the spray well centerline in a local downstream direction.21. The fuel injector as claimed in claim 17, wherein the local streamwise direction has axial component parallel to a nozzle axis about which the annular nozzle housing is circumscribed and a circumferential component around the nozzle housing.22. The fuel injector as claimed in claim 17 further comprising each of the spray wells having a radially extending wall portion substantially parallel to the spray well centerline and a well portion asymmetrically flared out from the spray well centerline and extending away from the radially extending wall portion.23. The fuel injector as claimed in claim 22, wherein the local streamwise direction is an upstream direction.24. The fuel injector as claimed in claim 22, wherein the local streamwise direction is a downstream direction.25. The fuel injector as claimed in claim 22, further comprising a first plurality of the spray wells having the well portions asymmetrically flared out with respect to the spray well centerline in a local upstream direction and a second plurality of the spray wells having the well portions asymmetrically flared out with respect to the spray well centerline in a local downstream direction.26. The fuel injector as claimed in claim 25, wherein the local streamwise direction has axial component parallel to a nozzle axis about which the annular nozzle housing is circumscribed and a circumferential component around the nozzle housing.27. The fuel injector as claimed in claim 25, further comprising a lip around a portion of each of the spray wells along the asymmetrically flared out well portions.28. The fuel injector as claimed in claim 16, further comprising the spray wells having at least two types of the well portions chosen from a group consisting of symmetrically flared out well portions, asymmetrically upstream flared out well portions flared outwardly with respect to the spray well centerline in a local upstream direction, and asymmetrically downstream flared out well portions flared outwardly with respect to the spray well centerline in a local downstream direction.29. The fuel injector as claimed in claim 28, further comprising adjacent ones of the spray orifices in each of the clockwise and the counterclockwise extending annular legs are aligned with spray wells having different types of the well portions chosen from the group.30. The fuel injector as claimed in claim 29, further comprising a single trunk line connected to the first and second fuel circuit branches.31. The fuel injector as claimed in claim 29, further comprising a shutoff valve operably disposed in fluid communication between the first and second fuel circuit branches.32. The fuel injector as claimed in claim 16, further comprising a shutoff valve operably disposed in fluid communication between the first and second fuel circuit branches.33. The fuel injector as claimed in claim 32, further comprising:the spray wells being symmetric spray wells, upstream and downstream annular rows and of the symmetric spray wells, and the differential pressure means including an annular row of radial flow swirlers radially outwardly disposed around the upstream annular row of the spray wells. 34. The fuel injector as claimed in claim 16, further comprising:the annular fuel nozzle formed from a single feed strip having a single bonded together pair of lengthwise extending plates, each of said plates having a single row of widthwise spaced apart and lengthwise extending parallel grooves, and the plates being bonded together such that opposing grooves in each of said plates are aligned forming the main nozzle fuel circuit and the pilot nozzle fuel circuit. 35. The conduit as claimed in claim 34, further comprising the clockwise and counterclockwise extending annular legs having parallel first and second waves, respectively.36. The conduit as claimed in claim 35, further comprising the spray orifices being located in alternating ones of the first and second waves so as to be substantially aligned along a circle.37. The fuel injector as claimed in claim 36, further comprising the spray wells having at least two types of the well portions chosen from a group consisting of symmetrically flared out well portions, asymmetrically upstream flared out well portions flared outwardly with respect to the spray well centerline in a local upstream direction, and asymmetrically downstream flared out well portions flared outwardly with respect to the spray well centerline in a local downstream direction.38. The fuel injector as claimed in claim 37, further comprising adjacent ones of the spray orifices in each of the clockwise and the counterclockwise extending annular legs are aligned with spray wells having different types of the well portions chosen from the group.39. The fuel injector as claimed in claim 38, further comprising a single trunk line connected to the first and second fuel circuit branches.40. The fuel injector as claimed in claim 38, further comprising a shutoff valve operably disposed in fluid communication between the first and second fuel circuit branches.41. The fuel injector as claimed in claim 34, further comprising:the spray wells being symmetric spray wells, upstream and downstream annular rows of the symmetric spray wells, and the differential pressure means including an annular row of radial flow swirlers radially outwardly disposed around the upstream annular row of the spray wells. 42. The fuel injector as claimed in claim 41, further comprising a fuel control valve:the spray wells being symmetric spray wells, upstream and downstream annular rows of the symmetric-spray wells, and the differential pressure means including an annular row of radial flow swirlers radially outwardly disposed around the upstream annular row of the spray wells.