초록 ▼

A fuel nozzle sheath has a lateral opening for admitting air about a nozzle stern. The stress distribution along the perimeter of the window is smoothed out by increasing the corner radius of the window corner presenting the highest stress concentration. The different corner radii of the window open

A fuel nozzle sheath has a lateral opening for admitting air about a nozzle stern. The stress distribution along the perimeter of the window is smoothed out by increasing the corner radius of the window corner presenting the highest stress concentration. The different corner radii of the window opening in the sheath allows to reduce stresses resulting from the load transferred from the combustor liner to the sheath.

대표청구항 ▼

1. A fuel nozzle sheath adapted to be mounted about a gas turbine engine fuel nozzle stem having a spray tip, the sheath comprising a tubular body having a perimeter and extending longitudinally from a first end to an opposite second end, the first end surrounds an inlet portion of the fuel nozzle s

1. A fuel nozzle sheath adapted to be mounted about a gas turbine engine fuel nozzle stem having a spray tip, the sheath comprising a tubular body having a perimeter and extending longitudinally from a first end to an opposite second end, the first end surrounds an inlet portion of the fuel nozzle stem while the second end surrounds the spray tip, and a lateral opening defined through the tubular body and extending longitudinally along at least a portion of said perimeter, said lateral opening being bounded by a top edge, a bottom edge and two side edges, the lateral opening having top rounded inside corners at the junctions of the side edges and the top edge, and bottom rounded inside corners at the junctions of said side edges and the bottom edge, the radius of at least one of said top rounded inside corners being larger than the radii of the bottom rounded inside corners when projected in a same plane. 2. The fuel nozzle sheath of claim 1, wherein said at least one corner is known to be exposed to higher stresses than the other rounded inside corners of the lateral opening during use. 3. The fuel nozzle sheath of claim 1, wherein the radius of said at least one top rounded inside corner is about two times greater than the radii of the other rounded inside corners. 4. The fuel nozzle sheath of claim 1, wherein only one of the top rounded inside corners has a radius larger than the other rounded inside corners. 5. The fuel nozzle sheath of claim 1, wherein the top rounded inside corners are located at a first distance from an edge of said first end, the bottom rounded inside corners being corners located at a second distance from said edge of said inlet end, the first distance being smaller than the second distance. 6. The fuel nozzle sheath of claim 1, wherein said lateral opening has a generally rectangular configuration, and wherein the lateral opening extends along about half of the perimeter of the tubular body. 7. The fuel nozzle sheath of claim 1, wherein out of the four rounded inside corners, three have a radius R1 and one of the top rounded inside corners has a radius R2, and wherein R2/R1 is comprised between about 1.5 to about 2.0. 8. The fuel nozzle sheath of claim 1, wherein said lateral opening has a width comprised in a range of about 35% to about 50% of the perimeter of the tubular body. 9. A gas turbine engine fuel nozzle comprising: a fuel conveying member defining at least one fuel passage, a spray tip connected in fluid flow communication with said at least one fuel passage, said spray tip having an air discharged openings, a sheath provided about said fuel conveying member, an air passage defined between said fuel conveying member and said sheath, said air passage leading to said air discharged openings, a window defined in said sheath for supplying air to said air passage, said window being circumscribed by a top edge, a bottom edge, and first and second side edges, the window having first and second top rounded inside corners defined at a junction of the top edge and the first and second side edges respectively, the window further having first and second bottom rounded inside corners defined at a junction of the bottom edge and the first and second side edges, respectively, at least one of the first and second top and bottom rounded inside corners presenting a stress concentration which is greater than that of other rounded inside corners of the window, and wherein said stress concentration is smoothed out by increasing a radius of curvature of said at least one inside radius corner relative to a radius of the other corners as measured when projected in a same plane. 10. The fuel nozzle as defined in claim 9, wherein the window is defined about a portion of a circumference of the sheath and has two opposed ends, said increased radius of curvature being provided at only one of said opposed ends. 11. The fuel nozzle as defined in claim 10, wherein only one of said first and second top and bottom rounded inside corners has a greater radius of curvature than the others. 12. The fuel nozzle as defined in claim 11, wherein the first and second top rounded inside corners are located closer to the spray tip than the first and second bottom rounded inside corners, and wherein said increased radius of curvature is provided at one of said first and second to rounded inside corners. 13. The fuel nozzle as defined in claim 9, wherein the window has a generally rectangular shape and extends about a portion of the circumference of the sheath, only one of the top and bottom rounded inside corners having a radius larger than the other corners. 14. The fuel nozzle as defined in claim 9, wherein the increased radius is about two times greater than the radius of other rounded inside corners of the window.