Gas Turbine Pattern Swirl Film Cooling

Abstract

A turbine airfoil includes a blade having a leading and trailing edges and an internal cooling circuit, and a plurality of film holes extending between the internal cooling circuit and an exterior of the blade. The plurality of film holes are shaped to generate a swirling flow exiting the film holes adjacent the leading edge to thereby enhance local convection and provide an insulating barrier to gaspath flow.

What is claimed is: 
     
         1 . A turbine airfoil comprising:
 a blade including a pressure sidewall and a suction sidewall joined together at chordally opposite leading and trailing edges;   at least one cooling hole disposed between the pressure sidewall and the suction sidewall adjacent the leading edge; and   a plurality of curved film holes extending between the at least one cooling hole and an exterior of the blade.   
     
     
         2 . A turbine airfoil according to  claim 1 , wherein the curved film holes are helical. 
     
     
         3 . A turbine airfoil according to  claim 2 , wherein the plurality of helical film holes are oriented in clockwise and counter-clockwise directions. 
     
     
         4 . A turbine airfoil according to  claim 2 , wherein adjacent ones of the plurality of helical film holes are oriented in opposite directions. 
     
     
         5 . A turbine airfoil according to  claim 2 , wherein first groups of the helical film holes are oriented in one direction and second groups of the helical film holes are oriented in an opposite direction. 
     
     
         6 . A turbine airfoil according to  claim 5 , wherein the first groups and second groups alternate along a length of the blade. 
     
     
         7 . A turbine airfoil according to  claim 5 , wherein each of the first and second groups comprises three helical film holes. 
     
     
         8 . A turbine airfoil according to  claim 2 , wherein at least one of the plurality of helical film holes comprises a double helical film hole. 
     
     
         9 . A turbine airfoil comprising:
 a blade having a leading edge and a trailing edge and including an internal cooling circuit; and   a plurality of film holes extending between the internal cooling circuit and an exterior of the blade, the plurality of film holes being shaped to generate a swirling flow exiting the film holes adjacent the leading edge to thereby enhance local convection and provide an insulating barrier to gaspath flow.   
     
     
         10 . A turbine airfoil according to  claim 9 , wherein the plurality of film holes are helical film holes. 
     
     
         11 . A turbine airfoil according to  claim 10 , wherein the helical film holes are oriented in clockwise and counter-clockwise directions. 
     
     
         12 . A turbine airfoil according to  claim 10 , wherein adjacent ones of the helical film holes are oriented in opposite directions. 
     
     
         13 . A turbine airfoil according to  claim 10 , wherein first groups of the helical film holes are oriented in one direction and second groups of the helical film holes are oriented in an opposite direction. 
     
     
         14 . A turbine airfoil according to  claim 13 , wherein the first groups and second groups alternate along a length of the blade. 
     
     
         15 . A turbine airfoil according to  claim 13 , wherein each of the first and second groups comprises three helical film holes. 
     
     
         16 . A turbine airfoil according to  claim 9 , wherein at least one of the helical film holes comprises a double helical film hole. 
     
     
         17 . A method of film cooling a turbine airfoil including a blade with a leading edge and a trailing edge and having an internal cooling circuit, the method comprising:
 delivering cooling air to the internal cooling circuit; and   flowing the cooling air from the internal cooling circuit through a plurality of film holes extending between the internal cooling circuit and an exterior of the blade, the flowing step comprising swirling the cooling air in the film holes and thereby providing an insulating barrier to gaspath flow.   
     
     
         18 . A method according to  claim 17 , wherein the plurality of film holes comprise helical film holes, and wherein the flowing step is practiced by flowing the cooling air from the internal cooling circuit through the helical film holes.