Airfoil

1. An airfoil, comprising:

a. an interior surface;

b. an exterior surface opposed to the interior surface, wherein the exterior surface comprises a pressure side, a suction side opposed to the pressure side, a stagnation line between the pressure and suction sides, and a trailing edge between the pressure and suction sides and downstream from the stagnation line;

c. a plurality of stagnation trench segments forming a radial column of stagnation trench segments on the exterior surface, wherein the stagnation line passes through at least a portion of each of the stagnation trench segments, the plurality of stagnation trench segments comprising a first stagnation trench segment having a first end radially and axially spaced from a second end, and a second stagnation trench segment radially adjacent to the first stagnation trench segment and having a first end radially and axially spaced from a second end, wherein the second end of the first stagnation trench segment radially overlap with the first end of the second stagnant trench segment; and

d. at least one cooling passage in each stagnation trench segment, wherein the cooling passages provide fluid communication from the interior surface to the exterior surface.

2. The airfoil as in claim 1 , wherein at least one stagnation trench segment is arcuate.

3. The airfoil as in claim 1 , wherein at least one stagnation trench segment has a varying dimension along a length of the at least one stagnation trench segment.

4. The airfoil as in claim 1 , wherein at least one stagnation trench segment has a decreasing dimension, and the at least one cooling passage in the at least one stagnation trench segment is angled toward the decreasing dimension.

5. The airfoil as in claim 1 , further comprising a column of overlapping pressure side trench segments on the pressure side.

6. The airfoil as in claim 5 , further comprising a column of overlapping suction side trench segments on the suction side.

7. The airfoil as in claim 5 , further comprising at least one side cooling passage in each pressure side trench segment, wherein the side cooling passages provide fluid communication from the interior surface to the exterior surface.

8. The airfoil as in claim 7 , wherein the side cooling passages in the pressure side trench segments are radially offset from the cooling passages in the stagnation trench segments.

9. An airfoil, comprising:

a. an interior surface;

b. an exterior surface opposed to the interior surface, wherein the exterior surface comprises a pressure side, a suction side opposed to the pressure side, a stagnation line between the pressure and suction sides, and a trailing edge between the pressure and suction sides and downstream from the stagnation line;

c. a plurality of pressure side trench segments on the pressure side forming a radial column of pressure side trench segments, the plurality of pressure side trench segments comprising a first pressure side trench segment having a first end radially and axially spaced from a second end, and a second pressure side trench segment radially adjacent to the first pressure side trench segment and having a first end radially and axially spaced from a second end, wherein the second end of the first pressure side trench segment radially overlaps with the first end of the second pressure side trench segment;

d. a plurality of suction side trench segments on the suction side forming a radial column of suction side trench segments, the plurality of suction side trench segments comprising a first suction side trench segment having a first end radially and axially spaced from a second end, and a second suction side trench segment radially adjacent to the first suction side trench segment and having a first end radially and axially spaced from a second end, wherein the second end of the first suction side trench segment radially overlaps with the first end of the second suction side trench segment; and

e.

f. at least one side cooling passage in each pressure side trench segment and in each suction side trench segment, wherein the side cooling passages provide fluid communication from the interior surface to the exterior surface.

10. The airfoil as in claim 9 , further comprising a column of overlapping stagnation trench segments on the exterior surface, wherein the stagnation line passes through at least a portion of each of the overlapping stagnation trench segments.

11. The airfoil as in claim. 10 , wherein at least one stagnation trench segment is arcuate.

12. The airfoil as in claim 10 , wherein at least one stagnation trench segment has a varying dimension along a length of the at least one stagnation trench segment.

13. The airfoil as in claim 10 , wherein at least one stagnation trench segment has a decreasing dimension, and the at least one cooling passage in the at least one stagnation trench segment is angled toward the decreasing dimension.

14. The airfoil as in claim 10 , further comprising at least one cooling passage in each stagnation trench segment, wherein the at least one cooling passage provides fluid communication from the interior surface to the exterior surface.

15. The airfoil as in claim 14 , wherein the side cooling passages in the pressure side trench segments are radially offset from the cooling passages in the stagnation trench segments.

16. An airfoil, comprising:

a. an interior surface;

b. an exterior surface opposed to the interior surface, wherein the exterior surface comprises a pressure side, a suction side opposed to the pressure side, a stagnation line between the pressure and suction sides, and a trailing edge between the pressure and suction sides and downstream from the stagnation line;

c. a plurality of stagnation trench segments forming a radial column of stagnation trench segments on the exterior surface, wherein the stagnation line passes through at least a portion of each of the stagnation trench segments, the plurality of stagnation trench segments comprising a first stagnation trench segment having a first end radially and axially spaced from a second end, and a second stagnation trench segment radially adjacent to the first stagnation trench segment and having a first end radially and axially spaced from a second end, wherein the second end of the first stagnation trench segment radially overlaps with the first end of the second stagnant trench segment;

d. at least one cooling passage in each stagnation trench segment, wherein the at least one cooling passage provides fluid communication from the interior surface to the exterior surface;

e. a plurality of pressure side trench segments on the pressure side forming a radial column of pressure side trench segments, the plurality of pressure side trench segments comprising a first pressure side trench segment having a first end radially and axially spaced from a second end, and a second pressure side trench segment radially adjacent to the first pressure side trench segment and having a first end radially and axially spaced from a second end, wherein the second end of the first pressure side trench segment radially overlaps with the first end of the second pressure side trench segment;

f. a plurality of suction side trench segments on the suction side forming a radial column of suction side trench segments, the plurality of suction side trench segments comprising a first suction side trench segment having a first end radially and axially spaced from a second end, and a second suction side trench segment radially adjacent to the first suction side trench segment and having a first end radially and axially spaced from a second end, wherein the second end of the first suction side trench segment radially overlaps with the first end of the second suction side trench segment; and

g. at least one side cooling passage in each pressure side trench segment and in each suction side trench segment, wherein the side cooling passages provide fluid communication from the interior surface to the exterior surface.

17. The airfoil as in claim 16 , wherein at least one stagnation trench segment is arcuate.

18. The airfoil as in claim 16 , wherein at least one stagnation trench segment has a varying dimension along a length of the at least one stagnation trench segment.

19. The airfoil as in claim 16 , wherein at least one stagnation trench segment has a decreasing dimension, and the at least one cooling passage in the at least one stagnation trench segment is angled toward the decreasing dimension.

20. The airfoil as in claim 16 , wherein the side cooling passages in the pressure side trench segments are radially offset from the cooling passages in the stagnation trench segments.