Skewed tip hole turbine blade

1. A turbine rotor blade comprising:

an airfoil extending outwardly from a platform at a root thereof integrally formed with a supporting dovetail;

said airfoil including opposite pressure and suction sidewalls spaced apart to define an internal cooling circuit therein, and extending in span from said root to a tip floor at an opposite distal end, and extending in chord between opposite leading and trailing edges;

a squealer rib extending from said sidewalls around said floor to define an open tip cavity thereatop; and

a plurality of individual bowed tip holes extending through said floor in flow communication with said cooling circuit for receiving cooling air therefrom, and being asymmetrically skewed toward and terminating offset from said rib for directing said cooling air thereagainst.

2. A blade according to claim 1 wherein each of said tip holes includes a straight inlet extending substantially perpendicular through the bottom of said floor and a skewed outlet bowed from said inlet toward said rib.

3. A blade according to claim 2 wherein said outlet diverges in flow area from said inlet for diffusing said cooling air discharged therethrough.

4. A blade according to claim 3 wherein said outlet comprises:

a flat front wall inclined from said inlet outboard toward said rib;

a flat back wall spaced inboard from said front wall; and

a pair of flat sidewalls joining together said front and back walls to enclose said outlet.

5. A blade according to claim 4 wherein said rib joins said floor at a fillet, and said outlet terminates at said fillet.

6. A blade according to claim 5 wherein said back wall is colinear with said inlet.

7. A blade according to claim 5 wherein said back wall is inclined from said inlet outboard toward said inclined front wall.

8. A blade according to claim 5 wherein said pair of sidewalls in said outlet are inclined to diverge outwardly from said inlet.

9. A blade according to claim 8 wherein said front wall is inclined toward said rib at an inclination angle greater than said inclination of said outlet sidewalls.

10. A blade according to claim 5 further comprising a plurality of lugs integrally joined to said floor and rib, and spaced apart therealong, and each of said lugs includes a corresponding one of said tip holes extending therethrough in flow communication with said cooling circuit.

11. A gas turbine engine blade comprising a hollow airfoil having a plurality of discrete tip holes extending through a tip floor thereof and asymmetrically bowed toward and terminating offset from a squealer rib extending outwardly from said floor.

12. A gas turbine engine blade comprising:

a hollow airfoil including opposite pressure and suction sidewalls extending in span from a root to a tip floor and extending in chord between opposite leading and trailing edges, and a squealer rib extending integrally from said sidewalls to define an open tip cavity; and

a plurality of individual tip holes disposed through said floor along the base of said rib and skewed asymmetrically outboard toward and terminating offset from said rib for directing cooling air thereagainst.

13. A blade according to claim 12 wherein each of said tip holes includes a straight inlet extending through the bottom of said floor and a skewed outlet bowed from said inlet toward said rib.

14. A blade according to claim 13 wherein said outlet diverges in flow area from said inlet for diffusing said cooling air discharged therethrough.

15. A blade according to claim 14 wherein said outlet is asymmetric transversely toward said rib and symmetric laterally along said rib.

16. A blade according to claim 14 wherein said inlet is axisymmetrical.

17. A blade according to claim 14 wherein said outlet is quadrilateral.

18. A blade according to claim 17 wherein said inlet is substantially perpendicular with said floor, and said outlet includes a front wall inclined from said inlet toward said rib.

19. A blade according to claim 18 wherein said outlet further includes a back wall spaced inboard from said front wall, and a pair of sidewalls joining together said front and back walls to enclose said outlet.

20. A blade according to claim 19 wherein said back wall is colinear with said inlet.

21. A blade according to claim 19 wherein back wall is inclined from said inlet outboard toward said inclined front wall.

22. A blade according to claim 19 wherein said pair of sidewalls in said outlet are inclined to diverge outwardly from said inlet.

23. A blade according to claim 22 wherein said front wall is inclined toward said rib at an inclination angle greater than said inclination of said outlet sidewalls.

24. A blade according to claim 14 wherein said rib joins said floor at a fillet, and said outlet is spaced by said fillet from said rib.

25. A blade according to claim 14 wherein said rib joins said floor at a fillet, and said outlet terminates within said fillet.

26. A blade according to claim 14 wherein said rib joins said floor at a plurality of lugs spaced apart between said leading and trailing edges, and said plurality of tip holes are disposed in corresponding ones of said lugs.

27. A blade according to claim 26 wherein:

said tip hole outlet includes front and back walls inclined from said inlet toward said rib; and

said tip hole inlet extends substantially perpendicular to said floor and in part through the middle of said back wall.