Bullnose seal turbine stage

Abstract

A turbine stage includes a stator nozzle cooperating with a row of turbine blades. The nozzle includes a row of vanes mounted between inner and outer bands, with the inner band adjoining the blades at inner platforms thereof at a rotary seal. The inner band includes a stator bullnose at the trailing edge thereof cooperating with the rotary seal for reducing aerodynamic losses thereat.

1 . A turbine stage comprising:
 an annular stator nozzle including a row of vanes mounted between inner and outer bands, and said inner band includes a radially inwardly extending mounting flange;   a row of blades mounted to the perimeter of a rotor disk and spaced aft from said mounting flange to define a forward cavity for channeling purge air therethrough;   each blade including an inner platform adjoining said inner band at a rotary seal therewith disposed atop said forward cavity for discharging said purge air; and   said inner band having a stator bullnose at the trailing edge thereof cooperating with said rotary seal for reducing aerodynamic losses thereat.   
   
   
       2 . A stage according to  claim 1  wherein said blade platform includes a rotor bullnose joined to a blunt forward face extending radially inwardly therefrom to a rotor wing extending axially forwardly from said blunt face and spaced below said stator bullnose to define said rotary seal therewith. 
   
   
       3 . A stage according to  claim 2  wherein said stator bullnose axially overlaps said rotor wing and converges inwardly toward said rotor bullnose and said blunt face. 
   
   
       4 . A stage according to  claim 3  wherein said stator bullnose is convex radially inwardly past said rotor bullnose and terminates above said rotor wing at about mid-elevation of said blunt face. 
   
   
       5 . A stage according to  claim 4  wherein said inner band and platform are coextensive in elevation at said rotary seal, and converge radially inwardly between said stator and rotor bullnoses. 
   
   
       6 . A stage according to  claim 5  wherein:
 said stator bullnose commences at the trailing edges of said vanes, and extends aft toward said rotor bullnose; and   said rotor bullnose commences forward from a leading edge of said blade and terminates in a radially aligned blunt face.   
   
   
       7 . A stage according to  claim 6  wherein said stator and rotor bullnoses are fully convex in radial elevation. 
   
   
       8 . A stage according to  claim 6  wherein said stator bullnose has a larger radius of curvature than said rotor bullnose. 
   
   
       9 . A stage according to  claim 6  wherein said rotary seal further comprises a stator wing extending aft from said mounting flange below said rotor wing. 
   
   
       10 . A stage according to  claim 6  wherein said inner band further includes a lower surface under said stator bullnose disposed generally parallel to and axially overlapping said rotor wing. 
   
   
       11 . A turbine stage comprising:
 a stator nozzle including a row of vanes mounted between inner and outer bands;   a row of blades mounted to the perimeter of a rotor disk, and each blade having an inner platform adjoining said inner band at a rotary seal therewith; and   said inner band has a substantially full height bullnose at the trailing edge thereof cooperating with said rotary seal for reducing aerodynamic losses thereat.   
   
   
       12 . A stage according to  claim 11  wherein said blade platform includes a blunt forward face extending radially inwardly to a rotor wing extending axially forwardly therefrom and spaced below said bullnose to define said rotary seal therewith. 
   
   
       13 . A stage according to  claim 12  wherein said bullnose axially overlaps said rotor wing and converges inwardly toward said blunt face. 
   
   
       14 . A stage according to  claim 13  wherein said inner band further includes a lower surface under said bullnose disposed generally parallel to and axially overlapping said rotor wing. 
   
   
       15 . A stage according to  claim 14  wherein said bullnose is convex from the trailing edges of said vanes to said lower surface. 
   
   
       16 . A stage according to  claim 13  wherein said inner band and platform are coextensive in elevation at said rotary seal, and converge radially inwardly between said bullnose and blunt face. 
   
   
       17 . A stage according to  claim 16  wherein:
 said stator bullnose commences at the trailing edges of said vanes, and extends aft toward said platform; and   said platform extends forward from a leading edge of said blade and joins said blunt face at a rotor bullnose.   
   
   
       18 . A stage according to  claim 17  wherein said stator bullnose has a larger radius of curvature than said rotor bullnose. 
   
   
       19 . A stage according to  claim 13  wherein said inner band further comprises a mounting flange, and said rotary seal further comprises a stator wing extending aft from said mounting flange below said rotor wing. 
   
   
       20 . A stage according to  claim 19  further comprising a forward cavity disposed between said nozzle and rotor disk in flow communication with said rotary seal for discharging purge air therethrough.