Durable turbine nozzle

Abstract

A turbine nozzle includes a plurality of vanes joined at opposite ends to outer and inner bands. The inner band has a forward hook which is segmented to reduce thermal mismatch. And, in additional embodiments the vane includes an impingement baffle having preferential cooling.

1. A turbine nozzle for a gas turbine engine, comprising:
 a plurality of vanes integrally joined at opposite ends to outer and inner bands; and  
 said inner band having a forward hook inboard of a leading edge thereof, said hook including an inner lip and a plurality of circumferentially spaced apart outer lips spaced radially from said inner lip to define a retention slot therein.  
 
     
     
       2. A nozzle according to  claim 1  wherein said inner band is an arcuate segment, and said outer lips are disposed at opposite circumferential ends thereof and intermediate therebetween. 
     
     
       3. A nozzle according to  claim 1  wherein said vanes join said outer band at a compound radii fillet. 
     
     
       4. A nozzle according to  claim 3  wherein said fillet has a larger radius adjacent said vane than adjacent said outer bands. 
     
     
       5. A nozzle according to  claim 1  wherein:
 said vanes have a generally concave, pressure side and an opposite, generally convex, suction side extending between leading and trailing edges and between said outer and inner bands along respective spans of said vanes; and  
 said vanes include cavities having an impingement baffle, and said baffles have a plurality of spaced apart impingement holes extending therethrough and arranged in different patterns facing an inner surface of said cavities for preferentially channeling cooling air in impingement jets toward midspan of said vanes.  
 
     
     
       6. A nozzle according to  claim 5  wherein said impingement hole pattern on said vane pressure side is denser than said pattern on said vane suction side for preferentially cooling said vane midspan. 
     
     
       7. A nozzle according to  claim 6  wherein said baffles include imperforate regions at opposite span ends thereof that converge toward said midspan between said leading and trailing edges thereof. 
     
     
       8. A nozzle according to  claim 7  wherein:
 said impingement holes on said pressure and suction sides have equal size; and  
 said baffles include a row of larger impingement holes extending along leading edges thereof.  
 
     
     
       9. A nozzle according to  claim 5  wherein said baffles include a row of larger impingement holes extending along leading edges thereof. 
     
     
       10. A nozzle according to  claim 9  wherein said impingement holes have a greater flow density inside said vane leading edge than on said vane pressure and suction sides. 
     
     
       11. A nozzle according to  claim 9  wherein said baffle leading edge has a radius sufficient for forming said large impingement holes planar therein, and said vane leading edge has a correspondingly larger radius to complement said baffle leading edge. 
     
     
       12. A nozzle according to  claim 5  wherein said baffles complement said vane cavities for maintaining a uniform gap with said inner surfaces thereof between said vane leading and trailing edges. 
     
     
       13. A nozzle according to  claim 5  wherein said baffles include integral standoff pads for spacing said baffles from said vane inner surfaces, and said pads are arranged on opposite sides of said baffles at both leading and trailing edges thereof. 
     
     
       14. A nozzle according to  claim 13  wherein said pads are more uniformly spaced on said vane pressure side said than said suction side. 
     
     
       15. A turbine nozzle for a gas turbine engine, comprising:
 a plurality of vanes integrally joined at opposite ends to outer and inner bands;  
 said inner band having a forward hook inboard of a leading edge thereof, said hook including an inner lip and a plurality of circumferentially spaced apart outer lips spaced radially from said inner lip to define a retention slot therein;  
 said vanes have generally concave, pressure sides and opposite, generally convex, suction sides extending between leading and trailing edges thereof and between said outer and inner bands along respective spans of said vanes; and  
 said vanes include cavities each having an impingement baffle, and said baffles have a plurality of spaced apart impingement holes extending therethrough and arranged in different patterns facing an inner surface of said cavities for preferentially channeling cooling air in impingement jets toward midspan of said vane.  
 
     
     
       16. A nozzle according to  claim 15  wherein said baffles include imperforate regions at opposite span ends thereof that converge toward said midspan between said leading and trailing edges thereof. 
     
     
       17. A nozzle according to  claim 16  wherein said baffles include a row of larger impingement holes extending along leading edges thereof. 
     
     
       18. A nozzle according to  claim 17  wherein said inner band is an arcuate segment, and said outer lips are disposed at opposite circumferential ends thereof and intermediate therebetween. 
     
     
       19. A nozzle according to  claim 18  wherein said vanes join said outer band at a compound radii fillet. 
     
     
       20. A turbine nozzle for a gas turbine engine, said nozzle comprising:
   a radially inner band;        a radially outer band; and        at least one vane extending between said inner and outer bands, said vane comprising a first sidewall and a second sidewall connected together at a leading edge and a trailing edge to define a cavity therebetween; and        an impingement baffle positioned within the vane cavity, said impingement baffle comprising a plurality of first impingement baffle holes extending therethrough and a plurality of second impingement baffle holes extending therethrough, at least some of said first impingement baffle holes extending along said vane leading edge and having a first diameter, said second impingement baffle holes having a second diameter, said first diameter is larger than said second diameter, said impingement baffle leading edge having a radius sufficient for forming said first impingement baffle holes substantially planar therein, said at least one vane leading edge having a corresponding larger radius that substantially compliments said impingement baffle leading edge.     
     
     
       21. A turbine nozzle in accordance with  claim 20  wherein said plurality of first impingement baffle holes for channeling cooling fluid therethrough in impingement jets towards an inner surface of said at least one vane leading edge. 
     
     
       22. A turbine nozzle in accordance with  claim 20  wherein said first sidewall defines a pressure side of said at least one vane, said second sidewall defines a suction side of said at least one vane, said plurality of second impingement baffle holes arranged in a denser pattern along said pressure side than said suction side. 
     
     
       23. A turbine nozzle in accordance with  claim 20  wherein said plurality of second impingement baffle holes are each sized identically. 
     
     
       24. A turbine nozzle in accordance with  claim 20  wherein said plurality of first impingement baffle holes comprises a row of said first impingement holes each having said first diameter larger than said second diameter of each of said plurality of second impingement baffle holes. 
     
     
       25. A turbine nozzle in accordance with  claim 24  wherein said row of first impingement holes extends at least partially between said radially inner and outer bands. 
     
     
       26. A turbine nozzle in accordance with  claim 20  wherein at least one of said inner band and said outer band comprises a forward hook inboard of a leading edge thereof, said hook comprising an inner lip and a plurality of circumferentially- spaced apart outer lips spaced radially from said inner lip such that a slot is defined therein.   
     
     
       27. A turbine nozzle in accordance with  claim 20  further comprising a compound radii fillet extending between said at least one vane and at least one of said inner band and said outer band. 
     
     
       28. A turbine nozzle in accordance with  claim 27  wherein said compound radii fillet comprises a first radius and a second radius, said second radius larger than said first radius, said first radius between said second radius and at least one of said inner band and said outer band. 
     
     
       29. A turbine nozzle in accordance with  claim 20  wherein said at least one vane further comprises a plurality of projections extending outwardly from said impingement baffle, said projections configured to maintain a relative position of said impingement baffle with respect to said at least one vane such that a substantially uniform gap is defined between said impingement baffle and said at least one vane. 
     
     
       30. A turbine nozzle for a gas turbine engine, said nozzle comprising:
   a radially inner band;        a radially outer band; and        at least one vane extending between said inner and outer bands, said vane comprising a first sidewall and a second sidewall connected together at a leading edge and a trailing edge to define a cavity therebetween, said at least one vane formed integrally with said radially outer band such that a compound fillet extends between said radially outer band and said at least one vane, said compound fillet circumscribes said at least one vane, and comprises a first radius and a second radius that is larger than said first radius, said first radius extending between said second radius and at least one of said radially outer and inner bands.     
     
     
       31. A turbine nozzle in accordance with  claim 30  wherein said first sidewall defines a pressure side of said at least one vane, said second sidewall defines a suction side of said at least one vane, each said sidewall comprises a plurality of impingement baffle holes extending therethrough, said plurality of impingement baffle holes are arranged in a denser pattern along said vane pressure side than along said vane suction side. 
     
     
       32. A turbine nozzle in accordance with  claim 30  wherein at least one of said first and said second sidewall comprises a plurality of impingement baffle holes extending therethrough, said plurality of impingement baffle holes comprise a first row of impingement holes and a pattern of remaining impingement holes, at least some of said first row of impingement holes having a first diameter, said pattern of remaining impingement holes each having a second diameter that is smaller than said first diameter, said first row of impingement baffle holes extending along said vane leading edge. 
     
     
       33. A turbine nozzle in accordance with  claim 30  wherein said inner band comprises a forward hook inboard of a leading edge thereof, said hook comprising an inner lip and a plurality of circumferentially- spaced apart outer lips spaced radially from said inner lip such that a slot is defined therein.   
     
     
       34. A turbine nozzle for a gas turbine engine, said nozzle comprising at least one vane comprising a first sidewall and a second sidewall connected together at a leading edge and a trailing edge to define a cavity therebetween, the cavity sized to receive an impingement baffle therein, said impingement baffle comprising a plurality of impingement holes extending therethrough, said plurality of impingement holes comprising at least a row of first impingement holes for directing cooling airflow along an inner surface of said at least one vane leading edge, and a pattern of remaining impingement holes, at least some of said impingement holes have a first diameter, said remaining impingement holes have a second diameter, said first diameter is different than said second diameter, said impingement baffle leading edge has a radius sufficient for forming said first impingement holes substantially planar therein. 
     
     
       35. A turbine nozzle in accordance with  claim 34  wherein said at least one vane leading edge has a first radius that is larger than a second radius of said impingement baffle leading edge, said at least one vane first radius substantially compliments said impingement baffle leading edge second radius. 
     
     
       36. A turbine nozzle in accordance with  claim 34  wherein said inner band comprises a forward hook inboard of a leading edge thereof, said hook comprising an inner lip and a plurality of circumferentially- spaced apart outer lips spaced radially from said inner lip such that a slot is defined therein.   
     
     
       37. A turbine nozzle in accordance with  claim 34  further comprising a compound radii fillet extending between said outer band and each of said plurality of vanes. 
     
     
       38. A turbine nozzle in accordance with  claim 37  wherein each of said compound radii fillets comprises a first radius and a second radius, said first radius smaller than said second radius and extending between said second radius and said outer band. 
     
     
       39. A turbine nozzle in accordance with  claim 34  wherein said first diameter is larger than said second diameter. 
     
     
       40. A turbine nozzle in accordance with  claim 34  wherein said first sidewall defines a pressure side of said at least one vane, said second sidewall defines a suction side of said at least one vane, said plurality of impingement baffle holes arranged in a denser pattern along said pressure side than said suction side. 
     
     
       41. A turbine nozzle in accordance with  claim 34  wherein a gap is defined between said row of said impingement baffle leading edge and said at least one vane leading edge, said first row of impingement holes facilitates increasing a ratio of the cooling area behind said at least one vane within said gap to the cooling area external to said at least one vane leading edge. 
     
     
       42. A turbine nozzle in accordance with  claim 41  wherein said gap is substantially uniform between said at least one vane leading edge and said impingement baffle leading edge. 
     
     
       43. An impingement baffle for a turbine nozzle for use in a gas turbine engine, said impingement baffle comprising a first sidewall and a second sidewall connected together at a leading edge and a trailing edge, said impingement baffle further comprising a plurality of rows of impingement holes extending therethrough, said plurality of rows of impingement holes comprising at least a first row of first impingement holes extending along said baffle leading edge and a pattern of remaining impingement holes, at least some of said impingement holes have a first diameter and said remaining impingement holes have a second diameter, said first diameter is different than said second diameter, said impingement baffle leading edge has a radius sufficient for forming said first diameter first impingement holes substantially planar therein. 
     
     
       44. An impingement baffle in accordance with  claim 43  wherein said first diameter is larger than said second diameter. 
     
     
       45. An impingement baffle in accordance with  claim 43  wherein said first sidewall defines a pressure side of said impingement baffle, said second sidewall defines a suction side of said impingement baffle, said plurality of impingement baffle holes arranged in a denser pattern along said pressure side than said suction side. 
     
     
       46. An impingement baffle in accordance with  claim 43  further comprising a plurality of standoff pads extending outwardly, from at least one of said first sidewall and said second sidewall. 
     
     
       47. An impingement baffle in accordance with  claim 43  wherein the turbine nozzle includes at least one vane, said first row of first impingement holes facilitates impingement cooling of a leading edge of the turbine nozzle vane. 
     
     
       48. A turbine nozzle for a gas turbine engine, said nozzle comprising:
   a radially inner band;        a radially outer band; and        at least one vane extending between said radially inner and outer bands, said inner band comprising a leading edge and a forward hook radially inward of said leading edge, said forward hook comprising a radially inner lip and a plurality of circumferentially - spaced apart radially outer lips such that a retention slot is defined therebetween.     
     
     
       49. A turbine nozzle in accordance with  claim 48  wherein said at least one vane is formed integrally with at least one of said radially outer band and said radially inner band such that a compound fillet extends between said at least one vane and at least one of said radially outer and inner bands. 
     
     
       50. A turbine nozzle in accordance with  claim 49  wherein said compound fillet circumscribes said at least one vane and comprises a first radius and a second radius that is larger than said first radius, said first radius extending between said second radius and at least one of said radially inner and outer bands. 
     
     
       51. A turbine nozzle in accordance with  claim 48  further comprising an impingement baffle, said at least one vane comprises a first sidewall and a second sidewall connected together at a leading edge and a trailing edge to define a cavity therebetween, the cavity sized to receive said impingement baffle therein, said impingement baffle comprising a plurality of impingement holes extending therethrough. 
     
     
       52. A turbine nozzle in accordance with  claim 51  wherein said impingement baffle plurality of impingement holes comprise at least a row of first impingement holes for directing cooling airflow along an inner surface of said at least one vane leading edge, and a pattern of remaining impingement holes, at least some of said first impingement holes have a first diameter, said pattern of remaining impingement holes have a second diameter, said first diameter is different than said second diameter. 
     
     
       53. A turbine nozzle in accordance with  claim 51  wherein said impingement baffle leading edge has a radius sufficient for forming said first impingement holes substantially planar therein. 
     
     
       54. A turbine nozzle in accordance with  claim 51  wherein said at least one vane first sidewall defines a suction side of said at least one vane, said second sidewall defines a pressure side of said at least one vane, said impingement baffle plurality of impingement baffle holes arranged in a denser pattern along said vane pressure side than along said vane suction side. 
     
     
       55. A turbine nozzle in accordance with  claim 51  wherein said at least one vane leading edge has a first radius that is larger than a second radius of said impingement baffle leading edge, said at least one vane leading edge first radius substantially compliments said impingement baffle leading edge second radius.