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An airfoil (10) is disclosed for a gas turbine engine in which the airfoil (10) includes an internal cooling system (14) with one or more converging-diverging exit slots (20) configured to increase the effectiveness of the cooling system (14) at the trailing edge (34) of the airfoil (10) by increasi

An airfoil (10) is disclosed for a gas turbine engine in which the airfoil (10) includes an internal cooling system (14) with one or more converging-diverging exit slots (20) configured to increase the effectiveness of the cooling system (14) at the trailing edge (34) of the airfoil (10) by increasing the contact of cooling fluids with internal surfaces (24, 30) of the pressure and suction sides (36, 38) of the airfoil (10). In at least one embodiment, the trailing edge cooling channel (18) may include one or more converging-diverging exit slots (20) to further pressurize the trailing edge cooling channel (18) and may be formed by a first and second ribs (80, 82) extending between an outer walls (13, 12) forming the pressure and suction sides (36, 38). The converging-diverging exit slot (20) may be formed from a first converging section (84) having an inlet (86) with a larger cross-sectional area than an outlet (88) and is formed from a second diverging section (90) having an inlet (92) with a smaller cross-sectional area than an outlet (94).

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1. A turbine airfoil for a gas turbine engine comprising: a generally elongated hollow airfoil formed from an outer wall, and having a leading edge, a trailing edge, a pressure side, a suction side and a cooling system positioned within interior aspects of the generally elongated hollow airfoil;the

1. A turbine airfoil for a gas turbine engine comprising: a generally elongated hollow airfoil formed from an outer wall, and having a leading edge, a trailing edge, a pressure side, a suction side and a cooling system positioned within interior aspects of the generally elongated hollow airfoil;the cooling system includes at least one trailing edge cooling channel positioned at the trailing edge of the airfoil;wherein the at least one trailing edge cooling channel includes at least one converging-diverging exit slot formed by a first rib extending between the outer wall forming the pressure side and the outer wall forming the suction side and a second rib extending between the outer wall forming the pressure side and the outer wall forming the suction side;wherein the at least one converging-diverging exit slot is formed from a converging section having an inlet with a larger cross-sectional area than an outlet and is formed from a diverging section having an inlet with a smaller cross-sectional area than an outlet,at least one mini-rib extending from the pressure side into the converging-diverging exit slot,at least one mini-rib extending from the suction side into the converging-diverging exit slot,wherein the at least one mini-ribs are positioned in the diverging section such that the at least one mini-ribs extend downstream and from a cooling fluid flow path axis in different directions to enhance diffusion of cooling fluid exhausted from the diverging section. 2. The turbine airfoil of claim 1, wherein a chordwise extending length of the converging section is greater than a chordwise extending length of the diverging section. 3. The turbine airfoil of claim 2, wherein a chordwise extending length of the converging section is between 1.5 times and 4 times longer than the chordwise extending length of the diverging section. 4. The turbine airfoil of claim 1, wherein the outlet of the converging section has a cross-sectional area that is at least 25% less than a cross-sectional area of the inlet of the converging section. 5. The turbine airfoil of claim 1, wherein a cross-sectional area of the inlet of the converging section is about equal to a cross-sectional area of the outlet of the diverging section. 6. The turbine airfoil of claim 1, wherein the at least one mini-rib extending into the converging-diverging exit slot is nonparallel and nonorthogonal with a cooling fluid flow path axis extending through the converging-diverging exit slot. 7. The turbine airfoil of claim 6, wherein the at least one mini-rib extending into the converging-diverging exit slot has a leading end positioned closer to the second rib than a trailing end and the at least one mini-rib extending into the converging-diverging exit slot has a leading end positioned closer to the first rib than a trailing end. 8. The turbine airfoil of claim 1, wherein the at least one mini-rib extending into the converging-diverging exit slot is offset in a chordwise direction from another at least one mini-rib such that the mini-ribs do not overlap in a direction extending from the pressure side towards the suction side. 9. The turbine airfoil of claim 1, further comprising at least one mini-rib extending from the first rib toward the second rib in the converging section. 10. The turbine airfoil of claim 9, further wherein the at least one mini-rib extends from the second rib toward the first rib in the converging section. 11. The turbine airfoil of claim 10, wherein the at least one mini-rib extending from the first rib is aligned with the at least one mini-rib extending from the second rib. 12. The turbine airfoil of claim 1, further comprising a plurality of cooling fluid flow controllers extending from the outer wall forming the pressure side to the outer wall forming the suction side of the generally elongated hollow airfoil, where the cooling fluid flow controllers form a plurality of alternating zigzag channels extending downstream toward the trailing edge, and wherein the plurality of cooling fluid flow controllers are positioned upstream from the at least one converging-diverging exit slot. 13. The turbine airfoil of claim 12, wherein at least one of the cooling fluid flow controllers is formed by a pressure side that is on an opposite side from a suction side, whereby the pressure and suction sides are coupled together via a leading edge and trailing edge on an opposite end of the at least one cooling fluid flow controller from the leading edge and wherein the pressure side has a generally concave curved surface and the suction side has a generally convex curved surface. 14. The turbine airfoil of claim 13, wherein the plurality of cooling fluid flow controllers are collected into a first spanwise extending row of cooling fluid flow controllers and a second spanwise extending row, wherein each of the cooling fluid flow controllers within the first spanwise extending row of cooling fluid flow controllers is positioned similarly, such that a pressure side of one cooling fluid flow controller is adjacent to a suction side of an adjacent cooling fluid flow controller, except for a cooling fluid flow controller at an end of the first spanwise extending row, and wherein the second spanwise extending row of cooling fluid flow controllers are positioned downstream from the first spanwise extending row of cooling fluid flow controllers. 15. The turbine airfoil of claim 14, wherein the second spanwise extending row of cooling fluid flow controllers has at least one cooling fluid flow controller with a pressure side on an opposite side of the cooling fluid flow controller than in the first spanwise extending row of cooling fluid flow controllers, thereby causing cooling fluid flowing through the second spanwise extending row of cooling fluid flow controllers to be directed downstream with a spanwise vector that is opposite to a spanwise vector imparted on the cooling fluid by the first spanwise extending row of cooling fluid flow controllers. 16. The turbine airfoil of claim 1, further comprising a plurality of rows of pin fins extending from the outer wall forming the pressure side to the outer wall forming the suction side and downstream from the cooling fluid flow controllers. 17. A turbine airfoil for a gas turbine engine comprising: a generally elongated hollow airfoil formed from an outer wall, and having a leading edge, a trailing edge, a pressure side, a suction side and a cooling system positioned within interior aspects of the generally elongated hollow airfoil;the cooling system includes at least one trailing edge cooling channel positioned at the trailing edge of the airfoil;wherein the at least one trailing edge cooling channel includes at least one converging-diverging exit slot formed by a first rib extending between the outer wall forming the pressure side and the outer wall forming the suction side and a second rib extending between the outer wall forming the pressure side and the outer wall forming the suction side;wherein the at least one converging-diverging exit slot is formed from a converging section having an inlet with a larger cross-sectional area than an outlet and is formed from a diverging section having an inlet with a smaller cross-sectional area than an outlet,wherein a chordwise extending length of the converging section is greater than a chordwise extending length of the diverging section.