Turbine airfoil trailing edge cooling slot

Abstract

A turbine airfoil includes pressure and suction sidewalls extending along a span from a base to a tip. Spanwise spaced apart trailing edge cooling holes in pressure sidewall end at a trailing edge cooling slot extending chordally substantially to an airfoil trailing edge. Each cooling hole includes a curved inlet, a metering section with a constant area and constant width flow cross section, and a spanwise diverging section leading into slot. Axial partitions extend chordally between and radially separate cooling holes along span. Aft ends of partitions include swept boat tails. Upper and lower deck sidewalls spanwise bound a deck of slot and extend outward to an external surface of pressure sidewall. Fillets between sidewalls and deck have fillet radii substantially the same size as bottom corner radii of flow cross section of diverging sections adjacent bottom corner radii.

Accordingly, what is desired to be secured by Letters Patent of the United States is the invention as defined and differentiated in the following claims: 
     
         1 . A gas turbine engine turbine airfoil comprising:
 widthwise spaced apart pressure and suction sidewalls extending outwardly along a span from an airfoil base to an airfoil tip;   the pressure and suction sidewalls extending chordwise between opposite leading and trailing edges;   a spanwise row of spanwise spaced apart trailing edge cooling holes encased in the pressure sidewall and ending at a single spanwise extending trailing edge cooling slot extending chordally substantially to the trailing edge;   each of the cooling holes including in downstream serial cooling flow relationship, a curved inlet, a metering section with a constant area and constant width flow cross section, and a spanwise diverging section leading into the trailing edge cooling slot;   axial partitions extending chordally between and radially separating the cooling holes along the span; and   aft ends of the partitions including swept boat tails.   
     
     
         2 . The airfoil as claimed in  claim 1  further comprising a spanwise heights substantially greater than hole widths through the cooling holes. 
     
     
         3 . The airfoil as claimed in  claim 1  further comprising pressure and suction sidewall surfaces of the pressure and suction sidewalls respectively in the hole and the pressure sidewall surface being planar through the entire metering and diverging sections. 
     
     
         4 . The airfoil as claimed in  claim 3  further comprising the width being constant through the metering and diverging sections of the hole. 
     
     
         5 . The airfoil as claimed in  claim 1  further comprising:
 a deck in the slot extending chordwise or downstream from the diverging sections of the cooling holes substantially to the airfoil trailing edge, 
 the deck extending spanwise or radially outwardly from a bottommost one to a topmost one of the trailing edge cooling holes, 
 upper and lower deck sidewalls spanwise bounding the deck and extending from the deck to an external surface of the pressure sidewall, and 
 fillets in slot corners between the upper and lower deck sidewalls and the deck. 
 
     
     
         6 . The airfoil as claimed in  claim 5  further comprising the fillets having fillet radii substantially the same size as bottom corner radii of the flow cross section of the diverging sections adjacent the bottom corner radii. 
     
     
         7 . The airfoil as claimed in  claim 4  further comprising:
 the diverging section having a race track shaped flow cross section, 
 the race track shaped flow cross section including a rectangular section between spanwise spaced apart rounded or semi-circular inner and outer end sections having radii, 
 a deck in the slot extending chordwise or downstream from the diverging sections of the cooling holes substantially to the airfoil trailing edge, 
 the deck extending spanwise or radially outwardly from a bottommost one to a topmost one of the trailing edge cooling holes, upper and lower deck sidewalls spanwise bounding the deck and extending from the deck to an external surface of the pressure sidewall, 
 fillets in slot corners between the upper and lower deck sidewalls and the deck, and 
 the fillets having fillet radii substantially the same size as the radii of the flow cross section. 
 
     
     
         8 . The airfoil as claimed in  claim 1  further comprising:
 the boat tails being swept, 
 each of the boat tails including a boat tail trailing edge having an apex spanwise located between the pressure and suction sidewalls, 
 the boat tail trailing edge sweeping aftwardly or downstream from the apex, and 
 the boat tail trailing edge sweeping from the apex spanwise or radially outwardly to the pressure sidewall and inwardly to the suction sidewall from the apex. 
 
     
     
         9 . The airfoil as claimed in  claim 8  further comprising the swept boat tails including rounded cross sections through the aft ends of the partitions between spanwise pairs of adjacent cooling holes. 
     
     
         10 . The airfoil as claimed in  claim 9  further comprising the metering and diverging sections having a hole height to hole width ratio of the spanwise height and the hole width in a range of about 2:1 to 10:1. 
     
     
         11 . The airfoil as claimed in  claim 9  further comprising pressure and suction sidewall surfaces of the pressure and suction sidewalls respectively in the hole and the pressure sidewall surface being planar through the entire metering and diverging sections. 
     
     
         12 . The airfoil as claimed in  claim 11  further comprising the width being constant through the metering and diverging sections of the hole. 
     
     
         13 . The airfoil as claimed in  claim 12  further comprising the inlet being downstream converging or bellmouth shaped. 
     
     
         14 . A gas turbine engine turbine airfoil comprising:
 widthwise spaced apart pressure and suction sidewalls extending outwardly along a span from an airfoil base to an airfoil tip;   the pressure and suction sidewalls extending chordwise between opposite leading and trailing edges;   a spanwise row of spanwise spaced apart trailing edge cooling holes encased in the pressure sidewall and ending at a single spanwise extending trailing edge cooling slot extending chordally substantially to the trailing edge;   each of the cooling holes including in downstream serial cooling flow relationship, a curved inlet, a metering section, and a spanwise diverging section leading into the trailing edge cooling slot;   axial partitions extending chordally between and radially separating the cooling holes along the span; and   aft ends of the partitions including swept boat tails.   
     
     
         15 . The airfoil as claimed in  claim 14  further comprising:
 the boat tails being swept, 
 each of the boat tails including a boat tail trailing edge having an apex spanwise located between the pressure and suction sidewalls, 
 the boat tail trailing edge sweeping aftwardly or downstream from the apex, and 
 the boat tail trailing edge sweeping from the apex spanwise or radially outwardly to the pressure sidewall and inwardly to the suction sidewall from the apex. 
 
     
     
         16 . The airfoil as claimed in  claim 15  further comprising the swept boat tails including rounded cross sections through the aft ends of the partitions between spanwise pairs of adjacent cooling holes. 
     
     
         17 . The airfoil as claimed in  claim 16  further comprising:
 a deck in the slot extending chordwise or downstream from the diverging sections of the cooling holes substantially to the airfoil trailing edge, 
 the deck extending spanwise or radially outwardly from a bottommost one to a topmost one of the trailing edge cooling holes, upper and lower deck sidewalls spanwise bounding the deck and extending from the deck to an external surface of the pressure sidewall, and 
 fillets in slot corners between the upper and lower deck sidewalls and the deck. 
 
     
     
         18 . The airfoil as claimed in  claim 17  further comprising the fillets having fillet radii substantially the same size as bottom corner radii of the flow cross section of the diverging sections adjacent the bottom corner radii. 
     
     
         19 . The airfoil as claimed in  claim 16  further comprising:
 the diverging section having a race track shaped flow cross section, 
 the race track shaped flow cross section including a rectangular section between spanwise spaced apart rounded or semi-circular inner and outer end sections having radii, 
 a deck in the slot extending chordwise or downstream from the diverging sections of the cooling holes substantially to the airfoil trailing edge, 
 the deck extending spanwise or radially outwardly from a bottommost one to a topmost one of the trailing edge cooling holes, upper and lower deck sidewalls spanwise bounding the deck and extending from the deck to an external surface of the pressure sidewall, 
 fillets in slot corners between the upper and lower deck sidewalls and the deck, and 
 the fillets having fillet radii substantially the same size as the radii of the flow cross section. 
 
     
     
         20 . The airfoil as claimed in  claim 19  further comprising the metering and diverging sections having a hole height to hole width ratio of the spanwise height and the hole width in a range of about 2:1 to 10:1.