Turbine airfoil trailing edge bifurcated cooling holes

Abstract

A gas turbine engine turbine airfoil having pressure and suction sidewalls extending outwardly along a span and chordwise between opposite leading and trailing edges. A spanwise row of spaced apart bifurcated trailing edge cooling holes encased in the pressure sidewall end at corresponding trailing edge cooling slots extending chordally substantially to the trailing edge. Axially extending inter-hole partitions separate the cooling holes. An inlet between adjacent pairs of the inter-hole partitions includes a divergent inlet section. An axial intra-hole partition bifurcates the cooling hole into diverging upper and lower diverging sections downstream and aft of the divergent inlet section. A forward end of the intra-hole partition divides an aft end of the divergent inlet section into upper and lower inlet flowpaths leading to the upper and lower diverging sections leading into the trailing edge cooling slots.

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 bifurcated trailing edge cooling holes encased in the pressure sidewall and ending at corresponding spanwise spaced apart trailing edge cooling slots extending chordally substantially to the trailing edge;   axially extending inter-hole partitions spanwise separating the cooling holes from each other;   each of the cooling holes including an inlet between adjacent pairs of the inter-hole partitions;   the inlet including a divergent inlet section;   an axial intra-hole partition extending downstream towards the trailing edge bifurcating the cooling hole into spanwise spaced apart and spanwise diverging upper and lower diverging sections downstream and aft of the divergent inlet section;   a forward end of the intra-hole partition dividing or splitting an aft or downstream end of the divergent inlet section into spanwise spaced apart upper and lower inlet flowpaths leading to the upper and lower diverging sections respectively; and   the upper and lower diverging sections of each one of the cooling holes leading into a corresponding one of the trailing edge cooling slots.   
     
     
         2 . The airfoil as claimed in  claim 1  further comprising a spanwise height substantially greater than a hole width through the upper and lower diverging sections. 
     
     
         3 . The airfoil as claimed in  claim 2  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 upper and lower diverging sections. 
     
     
         4 . The airfoil as claimed in  claim 3  further comprising the width being constant through the upper and lower diverging sections. 
     
     
         5 . The airfoil as claimed in  claim 4  further comprising lands disposed between spanwise adjacent ones of the trailing edge cooling slots and slot floors in the trailing edge cooling slots between the lands. 
     
     
         6 . The airfoil as claimed in  claim 5  further comprising the lands angled away from the external surface by a land angle in a range between 0-5 degrees. 
     
     
         7 . The airfoil as claimed in  claim 5  further comprising the lands being coplanar or flush with an external surface of the pressure sidewall around each of the cooling slots. 
     
     
         8 . The airfoil as claimed in  claim 1  further comprising the inlet being a convergent divergent inlet including in downstream serial flow relationship a convergent inlet section, a throat, and the divergent inlet section. 
     
     
         9 . The airfoil as claimed in  claim 8  further comprising:
 a spanwise height substantially greater than a hole width through the upper and lower diverging sections, 
 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 upper and lower diverging sections, 
 the width being constant through the upper and lower diverging sections, and 
 lands disposed between spanwise adjacent ones of the trailing edge cooling slots and slot floors in the trailing edge cooling slots between the lands. 
 
     
     
         10 . The airfoil as claimed in  claim 9  further comprising the lands being coplanar or flush with an external surface of the pressure sidewall around each of the cooling slots. 
     
     
         11 . The airfoil as claimed in  claim 10  further comprising each of the upper and lower diverging sections and corresponding ones of the trailing edge cooling slots diverging at different first and second diverging angles respectively. 
     
     
         12 . The airfoil as claimed in  claim 5  further comprising:
 each of the upper and lower diverging sections 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, 
 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 corner radii, 
 fillets in slot corners between the lands and the slot floors, and 
 the fillets having fillet radii substantially the same size as the corner radii of the flow cross section. 
 
     
     
         13 . The airfoil as claimed in  claim 12  further comprising the lands being coplanar or flush with an external surface of the pressure sidewall around each of the cooling slots. 
     
     
         14 . The airfoil as claimed in  claim 12  further comprising the lands angled away from the external surface by a land angle in a range between 0-5 degrees. 
     
     
         15 . The airfoil as claimed in  claim 13  further comprising each of the upper and lower diverging sections and corresponding ones of the trailing edge cooling slots diverging at different first and second diverging angles respectively. 
     
     
         16 . The airfoil as claimed in  claim 5  further comprising each of the upper and lower diverging sections and corresponding ones of the trailing edge cooling slots diverging at different first and second diverging angles respectively. 
     
     
         17 . The airfoil as claimed in  claim 16  further comprising the lands being coplanar or flush with an external surface of the pressure sidewall around each of the cooling slots. 
     
     
         18 . The airfoil as claimed in  claim 16  further comprising the lands angled away from the external surface by a land angle in a range between 0-5 degrees. 
     
     
         19 . The airfoil as claimed in  claim 5  further comprising:
 at least one of the cooling holes including a raised floor extending downstream through at least part of each of the diverging upper and lower diverging sections and into and at least partially through the corresponding cooling slot; 
 the raised floor including in downstream serial relationship a flat up ramp in the diverging section, a flat down ramp in the trailing edge cooling slot, and a transition section between the up and down ramps; 
 the up ramp ramping up from the suction sidewall surface and extending downstream; and 
 the down ramp ramping down and extending downstream from the transition section to the trailing edge. 
 
     
     
         20 . The airfoil as claimed in  claim 19  further comprising the lands being coplanar or flush with an external surface of the pressure sidewall around each of the cooling slots. 
     
     
         21 . The airfoil as claimed in  claim 20  further comprising the inlet being a convergent divergent inlet including in downstream serial flow relationship a convergent inlet section, a throat, and the divergent inlet section. 
     
     
         22 . The airfoil as claimed in  claim 21  further comprising:
 a spanwise height substantially greater than a hole width through the upper and lower diverging sections, 
 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 upper and lower diverging sections, 
 the width being constant through the upper and lower diverging sections, and 
 lands disposed between spanwise adjacent ones of the trailing edge cooling slots and slot floors in the trailing edge cooling slots between the lands. 
 
     
     
         23 . The airfoil as claimed in  claim 22  further comprising each of the upper and lower diverging sections and corresponding ones of the trailing edge cooling slots diverging at different first and second diverging angles respectively. 
     
     
         24 . The airfoil as claimed in  claim 1  further comprising:
 the inlet being a constant area inlet upstream of the divergent inlet section, 
 the inlet having a downstream extending first length, 
 the inlet including a metering section having a constant area flow cross section, and 
 metering section including a constant width and a constant height through the entire first length. 
 
     
     
         25 . The airfoil as claimed in  claim 24  further comprising:
 a spanwise height substantially greater than a hole width through the upper and lower diverging sections, 
 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 upper and lower diverging sections, 
 the width being constant through the upper and lower diverging sections, and 
 lands disposed between spanwise adjacent ones of the trailing edge cooling slots and slot floors in the trailing edge cooling slots between the lands. 
 
     
     
         26 . The airfoil as claimed in  claim 25  further comprising the lands being coplanar or flush with an external surface of the pressure sidewall around each of the cooling slots. 
     
     
         27 . The airfoil as claimed in  claim 25  further comprising the lands angled away from the external surface by a land angle in a range between 0-5 degrees. 
     
     
         28 . The airfoil as claimed in  claim 26  further comprising each of the upper and lower diverging sections and corresponding ones of the trailing edge cooling slots diverging at different first and second diverging angles respectively. 
     
     
         29 . The airfoil as claimed in  claim 28  further comprising:
 each of the upper and lower diverging sections 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, 
 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 corner radii, 
 fillets in slot corners between the lands and the slot floors, and 
 the fillets having fillet radii substantially the same size as the corner radii of the flow cross section.