Turbine airfoil cooling system with recessed trailing edge cooling slot

1. A turbine airfoil, comprising:

a generally elongated, hollow airfoil formed by an outer wall and having a leading edge, a trailing edge, a tip section at a first end, a root coupled to the airfoil at an end generally opposite the first end for supporting the airfoil and for coupling the airfoil to a disc, and a cooling system formed from at least one cavity in the elongated, hollow airfoil positioned in internal aspects of the generally elongated, hollow airfoil;

at least one trailing edge cooling slot positioned within the generally elongated, hollow airfoil and extending from the trailing edge chordwise into the generally elongated, hollow airfoil toward the leading edge such that a secondary trailing edge is offset upstream from the trailing edge, wherein the at least one trailing edge slot is defined by a pressure side wall and an opposite suction side wall that each define a portion of the generally elongated, hollow airfoil such that a downstream opening of the at least one trailing edge cooling slot is positioned in the trailing edge of the airfoil; and

wherein the cooling system includes a plurality of exhaust orifices positioned in the secondary trailing edge for exhausting cooling fluids from the cooling system.

2. The turbine airfoil of claim 1 , wherein the at least one trailing edge cooling slot extends from close proximity to the tip section of the generally elongated, hollow airfoil to terminate within close proximity of the root.

3. The turbine airfoil of claim 1 , wherein the at least one trailing edge cooling slot extends into a fillet at an intersection between a platform at the root and the generally elongated, hollow airfoil.

4. The turbine airfoil of claim 1 , wherein the at least one trailing edge cooling slot extends into the generally elongated, hollow airfoil a distance equal to about less than ten times an exhaust orifice diameter.

5. The turbine airfoil of claim 1 , wherein the at least one trailing edge cooling slot includes inboard and outboard side surfaces that are generally aligned with an outer wall at the tip section and with each other.

6. The turbine airfoil of claim 5 , wherein the exhaust orifices are separated from each other no more than a distance equal to about three times a width of an exhaust orifice.

7. The turbine airfoil of claim 1 , wherein the at least one trailing edge cooling slot includes inboard and outboard side surfaces that are curved toward each other.

8. The turbine airfoil of claim 1 , wherein the at least one trailing edge cooling slot includes inboard and outboard side surfaces that are linear and angled toward each other.

9. The turbine airfoil of claim 1 , further comprising ribs extending from the secondary trailing edge axially toward the trailing edge and terminating before reaching the trailing edge, wherein the ribs are tapered and have ever reducing cross-sectional area moving toward the trailing edge and wherein the ribs form diffusers.

10. A turbine airfoil, comprising:

a generally elongated, hollow airfoil formed by an outer wall and having a leading edge, a trailing edge, a tip section at a first end, a root coupled to the airfoil at an end generally opposite the first end for supporting the airfoil and for coupling the airfoil to a disc, and a cooling system formed from at least one cavity in the elongated, hollow airfoil positioned in internal aspects of the generally elongated, hollow airfoil;

at least one trailing edge cooling slot positioned within the generally elongated, hollow airfoil and extending from the trailing edge chordwise into the generally elongated, hollow airfoil toward the leading edge such that a secondary trailing edge is offset upstream from the trailing edge, wherein the at least one trailing edge slot is defined by a pressure side wall and an opposite suction side wall that each define a portion of the generally elongated, hollow airfoil such that a downstream opening of the at least one trailing edge cooling slot is positioned in the trailing edge of the airfoil;

wherein the cooling system includes a plurality of exhaust orifices positioned in the secondary trailing edge for exhausting cooling fluids from the cooling system; and

wherein the at least one trailing edge cooling slot extends into a fillet at an intersection between a platform at the root and the generally elongated, hollow airfoil.

11. The turbine airfoil of claim 10 , wherein the at least one trailing edge cooling slot extends from close proximity to the tip section of the generally elongated, hollow airfoil to terminate in the fillet at the root.

12. The turbine airfoil of claim 10 , wherein the at least one trailing edge cooling slot extends into the generally elongated, hollow airfoil a distance equal to about less than ten times an exhaust orifice diameter.

13. The turbine airfoil of claim 10 , wherein the at least one trailing edge cooling slot includes inboard and outboard side surfaces that are generally aligned with an outer wall at the tip section and with each other.

14. The turbine airfoil of claim 13 , wherein the exhaust orifices are separated from each other no more than a distance equal to about three times a width of an exhaust orifice.

15. The turbine airfoil of claim 10 , wherein the at least one trailing edge cooling slot includes inboard and outboard side surfaces that are curved toward each other.

16. The turbine airfoil of claim 10 , wherein the at least one trailing edge cooling slot includes inboard and outboard side surfaces that are linear and angled toward each other.

17. The turbine airfoil of claim 10 , further comprising ribs extending from the secondary trailing edge axially toward the trailing edge and terminating before reaching the trailing edge, wherein the ribs are tapered and have ever reducing cross-sectional area moving toward the trailing edge and wherein the ribs form diffusers.

18. A turbine airfoil, comprising:

a generally elongated, hollow airfoil formed by an outer wall and having a leading edge, a trailing edge, a tip section at a first end, a root coupled to the airfoil at an end generally opposite the first end for supporting the airfoil and for coupling the airfoil to a disc, and a cooling system formed from at least one cavity in the elongated, hollow airfoil positioned in internal aspects of the generally elongated, hollow airfoil;

at least one trailing edge cooling slot positioned within the generally elongated, hollow airfoil and extending from the trailing edge chordwise into the generally elongated, hollow airfoil toward the leading edge such that a secondary trailing edge is offset upstream from the trailing edge, wherein the at least one trailing edge slot is defined by a pressure side wall and an opposite suction side wall that each define a portion of the generally elongated, hollow airfoil such that a downstream opening of the at least one trailing edge cooling slot is positioned in the trailing edge of the airfoil;

wherein the cooling system includes a plurality of exhaust orifices positioned in the secondary trailing edge for exhausting cooling fluids from the cooling system; and

wherein the exhaust orifices are separated from each other no more than a distance equal to about three times a width of an exhaust orifice.

19. The turbine airfoil of claim 18 , wherein the at least one trailing edge cooling slot extends from close proximity to the tip section of the generally elongated, hollow airfoil to terminate in a fillet at an intersection between a platform at the root and the generally elongated, hollow airfoil.

20. The turbine airfoil of claim 18 , wherein the at least one trailing edge cooling slot includes inboard and outboard side surfaces that are generally aligned with an outer wall at the tip section and with each other and further comprising ribs extending from the secondary trailing edge axially toward the trailing edge and terminating before reaching the trailing edge, wherein the ribs are tapered and have ever reducing cross-sectional area moving toward the trailing edge and wherein the ribs form diffusers.