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A cooling system for a turbine airfoil of a turbine engine having an elbowed film cooling hole positioned in an outer wall defining the turbine airfoil. The elbowed film cooling hole may include a first section extending from an inner surface of the outer wall into the outer wall, an elbow coupled t

A cooling system for a turbine airfoil of a turbine engine having an elbowed film cooling hole positioned in an outer wall defining the turbine airfoil. The elbowed film cooling hole may include a first section extending from an inner surface of the outer wall into the outer wall, an elbow coupled to the first section in the outer wall, a second section attached to the elbow in the outer wall, and a diffusion slot attached to the second section, having an increasing width moving away from the second section, and extending to an opening in an outer surface of the outer wall. The cross-sectional areas of the first section, the elbow and the second section may be substantially equal to meter the flow of cooling fluids through the cooling system to efficiently add to the film cooling layer.

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I claim: 1. A turbine airfoil, comprising: a generally elongated airfoil 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 at least one

I claim: 1. A turbine airfoil, comprising: a generally elongated airfoil 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 at least one cavity forming a cooling system in the airfoil; an outer wall forming the generally elongated airfoil and having at least one elbowed film cooling hole positioned in the outer wall and providing a cooling fluid pathway between the at least one cavity forming the cooling system and outside of the airfoil; wherein the at least one elbowed film cooling hole includes a first section extending from an inner surface of the outer wall into the outer wall, an elbow coupled to the first section in the outer wall, a second section attached to the elbow in the outer wall at an end of the elbow that is generally opposite to an end to which the first section is attached, and a diffusion slot attached to the second section, having an increasing width moving away from the second section, and extending to an opening in an outer surface of the outer wall, wherein cross-sectional areas of the first section, the elbow and the second section are substantially equal; wherein the second section and the diffusion slot are aligned along an axis that is positioned at an angle to the outer surface of the airfoil between about 15 degrees and about 45 degrees. 2. The turbine airfoil of claim 1, wherein the elbow of the at least one elbowed film cooling hole changes the direction of flow of cooling fluids in the at least one elbowed film cooling hole between about 45 degrees and about 75 degrees. 3. The turbine airfoil of claim 2, wherein a downstream surface of the diffusion slot is positioned between about five degrees and about fifteen degrees from a longitudinal axis of the diffusion slot. 4. The turbine airfoil of claim 1, wherein an OD side surface of the diffusion slot is positioned between about five degrees and about fifteen degrees from a longitudinal axis of the diffusion slot. 5. The turbine airfoil of claim 1, wherein an ID side surface of the diffusion slot is positioned between about five degrees and about fifteen degrees from a longitudinal axis of the diffusion slot. 6. The turbine airfoil of claim 1, wherein the axis is positioned at an angle to the outer surface of the airfoil of about 25 degrees. 7. The turbine airfoil of claim 1, wherein the at least one elbowed film cooling hole comprises a plurality of elbowed film cooling holes positioned in the outer wall of the airfoil. 8. The turbine airfoil of claim 1, wherein the at least one elbowed film cooling hole comprises a plurality of elbowed film cooling holes positioned in the outer wall of the airfoil and positioned in spanwise rows, wherein the elbowed film cooling holes of adjacent spanwise rows are offset chordwise. 9. A turbine airfoil, comprising: a generally elongated airfoil 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 at least one cavity forming a cooling system in the airfoil; an outer wall forming the generally elongated airfoil and having at least one elbowed film cooling hole positioned in the outer wall and providing a cooling fluid pathway between the at least one cavity forming the cooling system and outside of the airfoil; wherein the at least one elbowed film cooling hole includes a first section extending from an inner surface of the outer wall into the outer wall, an elbow coupled to the first section in the outer wall, a second section attached to the elbow in the outer wall at an end of the elbow that is generally opposite to an end to which the first section is attached, and a diffusion slot attached to the second section, having an increasing width moving away from the second section. and extending to an opening in an outer surface of the outer wall, wherein cross-sectional areas of the first section, the elbow and the second section are substantially equal; wherein the at least one elbowed film cooling hole comprises a plurality of elbowed film cooling holes positioned in the outer wall of the airfoil; and wherein the plurality of elbowed film cooling holes are positioned in spanwise rows. 10. The turbine airfoil of claim 9, wherein elbowed film cooling holes of adjacent spanwise rows are offset chordwise. 11. The turbine airfoil of claim 9, wherein the second section and the diffusion slot are aligned along an axis that is positioned at an angle to the outer surface of the airfoil between about 15 degrees and about 45 degrees. 12. The turbine airfoil of claim 9, wherein the elbow of the at least one elbowed film cooling hole changes the direction of flow of cooling fluids in the at least one elbowed film cooling hole between about 45 degrees and about 75 degrees. 13. The turbine airfoil of claim 9, wherein a downstream surface of the diffusion slot is positioned between about five degrees and about fifteen degrees from a longitudinal axis of the diffusion slot. 14. The turbine airfoil of claim 9, wherein an OD side surface of the diffusion slot is positioned between about five degrees and about fifteen degrees from a longitudinal axis of the diffusion slot. 15. The turbine airfoil of claim 9, wherein an ID side surface of the diffusion slot is positioned between about five degrees and about fifteen degrees from a longitudinal axis of the diffusion slot. 16. A turbine airfoil, comprising: a generally elongated airfoil 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 at least one cavity forming a cooling system in the airfoil; an outer wall forming the generally elongated airfoil and having at least one elbowed film cooling hole positioned in the outer wall and providing a cooling fluid pathway between the at least one cavity forming the cooling system and outside of the airfoil; wherein the at least one elbowed film cooling hole includes a first section extending from an inner surface of the outer wall into the outer wall, an elbow coupled to the first section in the outer wall, a second section attached to the elbow in the outer wall at an end of the elbow that is generally opposite to an end to which the first section is attached, and a diffusion slot attached to the second section, having an increasing width moving away from the second section, and extending to an opening in an outer surface of the outer wall, wherein diameters of the first section, the elbow and the second section are substantially equal and wherein the elbow of the at least one elbowed film cooling hole changes the direction of flow of cooling fluids in the at least one elbowed film cooling hole between about 45 degrees and about 75 degrees; and wherein the at least one elbowed film cooling hole comprises a plurality of elbowed film cooling holes positioned in the outer wall of the airfoil in spanwise rows, wherein elbowed film cooling holes of adjacent spanwise rows are offset chordwise. 17. The turbine airfoil of claim 16, wherein the elbow of the at least one elbowed film cooling hole changes the direction of flow of cooling fluids in the at least one elbowed film cooling hole about 60 degrees. 18. The turbine airfoil of claim 16, wherein the downstream surface of the diffusion slot is positioned about ten degrees from the longitudinal axis of the diffusion slot. 19. The turbine airfoil of claim 16, wherein the OD side surface of the diffusion slot is positioned about ten degrees from a longitudinal axis of the diffusion slot, and the ID side surface of the diffusion slot is positioned about ten degrees from the longitudinal axis of the diffusion slot. 20. The turbine airfoil of claim 16, wherein an axis extending through the diffusion slot is positioned at an angle to the outer surface of the airfoil of about 25 degrees.