Airfoil mateface sealing

Abstract

An airfoil includes an airfoil working portion and an adjoining endwall. The endwall has a leading edge, a trailing edge, a first mateface, and a second mateface that collectively define a perimeter of the endwall, with the first and second matefaces arranged opposite one another. A forward zone is defined by the endwall that extends to the leading edge. The first and second matefaces are each oriented at an angle α II relative to radial in the forward zone. An aft zone is defined by the endwall that extends to the trailing edge. The first and second matefaces are each oriented at an angle α II relative to radial in the aft zone. The angles α II and α II are not equal. A middle zone is defined in between the forward and aft zones, and the first and second matefaces transition between the angles α II and α I in the middle zone.

1 . An airfoil for use in an airfoil cascade, the airfoil comprising:
 an airfoil working portion;   an endwall adjoining an end of the airfoil working portion, the endwall having a leading edge, a trailing edge, a first mateface, and a second mateface, wherein the first and second matefaces are arranged opposite one another, and wherein the leading edge, trailing edge, and first and second matefaces collectively define a perimeter of the endwall;   a forward zone defined by the endwall that extends to the leading edge, wherein the first and second matefaces are each oriented at an angle α II  relative to a radial direction in the forward zone;   an aft zone defined by the endwall that extends to the trailing edge, wherein the first and second matefaces are each oriented at an angle α I  relative to a radial direction in the aft zone, and wherein the angles α I  and α II  are not equal; and   a middle zone defined by the endwall in between the forward and aft zones, wherein the first and second matefaces transition between the angle α II  and the angle α I  in the middle zone.   
     
     
         2 . The airfoil of  claim 1 , wherein the endwall comprises a platform adjoining a root end of the airfoil working portion. 
     
     
         3 . The airfoil of  claim 1 , wherein the endwall is integrally and monolithically formed with the airfoil working portion. 
     
     
         4 . The airfoil of  claim 1 , wherein the angle α II  is in the range of approximately 0°≦α II ≦45°, and wherein the angle α I  is in the range of approximately −45°≦α I ≦0°. 
     
     
         5 . The airfoil of  claim 1 , wherein the angle α II  is in the range of approximately −45°≦α II ≦0°, and wherein the angle α I  is in the range of approximately 0°≦α I ≦45°. 
     
     
         6 . The airfoil of  claim 1 , wherein the angle α II  is approximately 0°, and wherein the angle α I  is in the range of approximately 0°<α I ≦45°. 
     
     
         7 . The airfoil of  claim 1 , wherein the angle α II  is in the range of approximately −45°≦α II <0°, and wherein the angle α I  is approximately 0°. 
     
     
         8 . The airfoil of  claim 1  and further comprising:
 a flowpath surface adjacent to each of the first and second matefaces and the leading and trailing edges, and that extends to the perimeter of the endwall; 
 a first flow modifying edge between the first mateface and the flowpath surface, wherein the first flow modifying edge extends along an entire length of the first mateface between the leading edge and the trailing edge; and 
 a second flow modifying edge between the second mateface and the flowpath surface, wherein the second flow modifying edge extends along an entire length of the second mateface between the leading edge and the trailing edge. 
 
     
     
         9 . An airfoil for using in an airfoil cascade, the airfoil comprising:
 an airfoil working portion;   an endwall adjoining an end of the airfoil working portion, the endwall having a leading edge, a trailing edge, a first mateface, a second mateface, and a flowpath surface, wherein the first and second matefaces are arranged opposite one another, and wherein the leading edge, trailing edge, and first and second matefaces collectively define a perimeter of the flowpath surface of the endwall;   a first flow modifying edge between the first mateface and the flowpath surface, wherein the first flow modifying edge extends along an entire length of the first mateface between the leading edge and the trailing edge; and   a second flow modifying edge between the second mateface and the flowpath surface, wherein the second flow modifying edge extends along an entire length of the second mateface between the leading edge and the trailing edge.   
     
     
         10 . The airfoil of  claim 9 , wherein the first flow modifying edge comprises an arcuate flow modifying edge. 
     
     
         11 . The airfoil of  claim 10 , wherein the arcuate flow modifying edge has a radius R in a range of approximately 0.127 to 6.35 mm (0.005 to 0.250 inch). 
     
     
         12 . The airfoil of  claim 10 , wherein the second flow modifying edge comprises an arcuate flow modifying edge configured substantially identically to the first flow modifying edge. 
     
     
         13 . The airfoil of  claim 9 , wherein the first flow modifying edge comprises a chamfered flow modifying edge. 
     
     
         14 . The airfoil of  claim 13 , wherein the chamfered flow modifying edge is defined at an angle θ with respect to the adjoining first mateface, and wherein the angle θ is in the range of approximately 45° to 75°. 
     
     
         15 . The airfoil of  claim 9  and further comprising:
 a forward zone defined by the endwall that extends to the leading edge, wherein the first and second matefaces each are oriented at an angle α II  relative to a radial direction in the forward zone, and wherein an absolute value of the angle α II  is in the range of approximately 0°≦|α II |≦45°; 
 an aft zone defined by the endwall that extends to the trailing edge, wherein the first and second matefaces each are oriented at an angle α I  relative to a radial direction in the aft zone, wherein an absolute value of the angle α I  is in the range of approximately 0°≦|α I |≦45°, and wherein the angles α I  and α II  are not equal; and 
 a middle zone defined by the endwall in between the forward and aft zones, wherein the first and second matefaces transition between the angle α II  and the angle α I  in the middle zone. 
 
     
     
         16 . The airfoil of  claim 15 , wherein the first and second matefaces are both substantially planar within the forward and aft zones. 
     
     
         17 . A method comprising:
 providing an endwall adjoining an end of an airfoil working portion, the endwall having a leading edge, a trailing edge, a first mateface, a second mateface, and a flowpath surface, wherein the first and second matefaces are arranged opposite one another, wherein the leading edge, trailing edge, and first and second matefaces collectively define a perimeter of the endwall, and wherein the flowpath surface is adjacent to each of the first and second matefaces and the leading and trailing edges;   defining a first flow modifying edge between the first mateface and the flowpath surface along an entire length of the first mateface between the leading edge and the trailing edge; and   defining a second flow modifying edge between the second mateface and the flowpath surface along an entire length of the second mateface between the leading edge and the trailing edge.   
     
     
         18 . The method of  claim 17  and further comprising:
 defining the first and second matefaces at an angle α II  relative to a radial direction in a forward zone of the endwall that extends to the leading edge; 
 defining the first and second matefaces at an angle α I  relative to the radial direction in an aft zone of the endwall that extends to the trailing edge, and wherein the angles α I  and α II  are not equal; and 
 defining a middle zone of the endwall in between the forward and aft zones, wherein the first and second matefaces transition between the angle α I  and the angle α II  in the middle zone. 
 
     
     
         19 . The method of  claim 17 , wherein the step of defining a first flow modifying edge comprises defining one of forming a chamfer and forming an arcuate edge at a radius R, wherein R is in a range of approximately 0.127 to 6.35 mm (0.005 to 0.250 inch). 
     
     
         20 . The method of  claim 17 , wherein the step of defining a second flow modifying edge comprises defining one of forming a chamfer and forming an arcuate edge at a radius R, wherein R is in a range of approximately 0.127 to 6.35 mm (0.005 to 0.250 inch)