Variable area turbine nozzle

Abstract

A gas-turbine engine ( 100 ) variable nozzle ( 460 ) includes an outer shroud ( 461 ), an inner shroud ( 462 ), and a variable nozzle airfoil ( 463 ). The outer shroud ( 461 ) includes a first spherical surface ( 466 ), a radially inner surface of the outer shroud ( 461 ). The inner shroud ( 462 ) includes a second spherical surface ( 467 ), a radially outer surface of the inner shroud ( 462 ). The variable nozzle airfoil ( 463 ) includes an outer edge ( 468 ) adjacent to the first spherical surface ( 466 ) and an inner edge ( 469 ) adjacent to the second spherical surface ( 467 ). The outer edge ( 468 ) has a curve which matches the contour of the first spherical surface ( 466 ). The inner edge ( 469 ) has a curve which matches the contour of the second spherical surface ( 467 ).

What is claimed is: 
     
         1 . A gas turbine engine variable nozzle, comprising:
 an outer shroud having
 a first spherical surface, the first spherical surface being a radially inner surface of the outer shroud, wherein the first spherical surface is the shape of a circumferential portion of a spherical zone; 
   an inner shroud located radially inward from the outer shroud, the inner shroud having
 a second spherical surface opposite the first spherical surface, the second spherical surface being a radially outer surface of the inner shroud, wherein the second spherical surface is the shape of a circumferential portion of a spherical zone; and 
   a variable nozzle airfoil extending radially between the first spherical surface and the second spherical surface, the variable nozzle airfoil having
 an outer edge adjacent to the first spherical surface, the outer edge having a curve which matches the contour of the first spherical surface, and 
 an inner edge adjacent to the second spherical surface, the inner edge having a curve which matches the contour of the second spherical surface. 
   
     
     
         2 . The variable nozzle of  claim 1 , wherein the first spherical surface and the second spherical surface are configured to form an annular exit in an axial direction. 
     
     
         3 . The variable nozzle of  claim 1 , further comprising a vane shaft extending from the variable nozzle airfoil through the outer shroud and beyond the outer shroud. 
     
     
         4 . The variable nozzle of  claim 3 , wherein the vane shaft extends within the variable nozzle airfoil. 
     
     
         5 . The variable nozzle of  claim 3 , wherein the vane shaft is angled between five and fifteen degrees in an axial direction with a radially outer portion of the vane shaft leaned in a forward direction. 
     
     
         6 . The variable nozzle of  claim 3 , further comprising a position selector coupled with the variable nozzle airfoil to fixedly lock the variable nozzle airfoil into one of a plurality of preselected positions. 
     
     
         7 . The variable nozzle of  claim 6 , wherein the position selector has a plate like shape and is located radially outward from the outer shroud, the position selector including:
 a forward edge located axially forward,   an aft edge located axially aft,   a first alignment edge located on a side of the position selector,   a second alignment edge located on a side of the position selector distal to the first alignment edge, wherein the first alignment edge and the second alignment edge are keyed to prevent independent rotation of adjacent position selectors installed within a gas turbine engine, and   a plurality of clocking positions configured for predetermined variable nozzle airfoil positions;   wherein the position selector is keyed to the vane shaft to prevent relative angular displacement between the position selector and the vane shaft.   
     
     
         8 . The variable nozzle of  claim 6 , further comprising a selector bolt configured to be inserted into any of the plurality of clocking positions. 
     
     
         9 . A gas turbine engine including a plurality of the variable nozzles of  claim 1 , wherein the plurality of the variable nozzles form a variable nozzle stage. 
     
     
         10 . A gas turbine engine variable nozzle assembly, comprising:
 a variable outer housing having
 a plurality of holes; 
   a variable nozzle located radially inward from the variable outer housing, the variable nozzle having
 an outer shroud including
 a first spherical surface, the first spherical surface being a radially inner surface of the outer shroud, wherein the first spherical surface is the shape of a circumferential portion of a spherical zone, 
 
 an inner shroud located radially inward from the outer shroud, the inner shroud including
 a second spherical surface opposite the first spherical surface, the second spherical surface being a radially outer surface of the inner shroud, wherein the second spherical surface is the shape of a circumferential portion of a spherical zone, and 
 
 a variable nozzle airfoil extending radially between the first spherical surface and the second spherical surface, the variable nozzle airfoil including
 an outer edge adjacent to the first spherical surface, the outer edge having a curve which matches the contour of the first spherical surface, and 
 an inner edge adjacent to the second spherical surface, the inner edge having a curve which matches the contour of the second spherical surface; and 
 
   an inter turbine duct axially preceding the variable nozzle, the inter turbine duct having
 an outer wall and 
 an inner wall located radially inward from the outer wall, 
 wherein the outer wall and the inner wall are configured to diverge as the inter turbine duct extends towards the variable nozzle. 
   
     
     
         11 . The variable nozzle assembly of  claim 10 , further comprising a position selector coupled with the variable nozzle airfoil to fixedly lock the variable nozzle airfoil into one of a plurality of preselected positions. 
     
     
         12 . The variable nozzle assembly of  claim 10 , wherein the position selector has a plate like shape and is located radially outward from the outer shroud, the position selector including:
 a forward edge located axially forward,   an aft edge located axially aft,   a first alignment edge located on a side of the position selector,   a second alignment edge located on a side of the position selector distal to the first alignment edge, wherein the first alignment edge and the second alignment edge are keyed to prevent independent rotation of adjacent position selectors installed within a gas turbine engine, and   a plurality of clocking positions configured for predetermined variable nozzle airfoil positions;   wherein the position selector is keyed to the vane shaft to prevent relative angular displacement between the position selector and the vane shaft.   
     
     
         13 . The variable nozzle assembly of  claim 12 , further comprising:
 the plurality of clocking positions including a cold position, a standard position, and a hot position.   
     
     
         14 . The variable nozzle assembly of  claim 13 , further comprising:
 the plurality of holes including a cold hole, a standard hole, and a hot hole;   wherein the cold position aligns with the cold hole for a cold operating condition, the standard position aligns with the standard hole for a standard operating condition, and the hot position aligns with the hot hole for a hot operating condition.   
     
     
         15 . The variable nozzle assembly of  claim 11 , further comprising:
 the variable outer housing including a plurality of dowel pins extending radially outward; and   each of the plurality of position selectors is configured to include a dowel hole extending partially into the position selector and configured to align with one of the plurality of dowel pins.   
     
     
         16 . The variable nozzle of  claim 10 , wherein the first spherical surface and the second spherical surface are configured to form an annular exit in an axial direction. 
     
     
         17 . The variable nozzle of  claim 10 , further comprising a vane shaft extending radially outward from the variable nozzle airfoil through the outer shroud and beyond the outer shroud. 
     
     
         18 . The variable nozzle of  claim 17 , wherein the vane shaft is angled between five and fifteen degrees in an axial direction with a radially outer portion of the vane shaft leaned in a forward direction. 
     
     
         19 . A gas turbine engine, comprising;
 an outer housing having
 a variable outer housing including
 a plurality of holes; 
 
   a variable nozzle located radially inward from the variable outer housing, the variable nozzle having
 an outer shroud including
 a first spherical surface, the first spherical surface being a radially inner surface of the outer shroud, wherein the first spherical surface is a circumferential portion of a first ring surface, the ring surface being the shape of a spherical zone, 
 
 an inner shroud located radially inward from the outer shroud, the inner shroud including
 a second spherical surface opposite the first spherical surface, the second spherical surface being a radially outer surface of the inner shroud, wherein the second spherical surface is a circumferential portion of a second ring surface, the second ring surface being the shape of a spherical zone, and 
 
 a variable nozzle airfoil extending radially between the first spherical surface and the second spherical surface, the variable nozzle airfoil including
 an outer edge adjacent to the first spherical surface, the outer edge having a curve which matches the contour of the first spherical surface, and 
 an inner edge adjacent to the second spherical surface, the inner edge having a curve which matches the contour of the second spherical surface; and 
 
   an inter turbine duct axially preceding the variable nozzle, the inter turbine duct having
 an outer wall, and 
 an inner wall located radially inward from the outer wall, 
 wherein the outer wall and the inner wall are configured to diverge as the inter turbine duct extends towards the variable nozzle. 
   
     
     
         20 . The gas turbine engine of  claim 19 , further comprising:
 a vane shaft extending through the outer shroud and beyond the outer shroud;   wherein the vane shaft is angled between five and fifteen degrees in an axial direction with a radially outer portion of the vane shaft leaned in the direction of a compressor of the gas turbine engine.