Airfoil for a gas turbine

1. An airfoil for a gas turbine comprising:

an outer structure comprising a first wall;

an inner structure comprising a second wall spaced relative to said first wall such that a cooling gap is defined between at least portions of said first and second walls, an inner surface of said second wall defining an inner cavity, said inner structure further comprising a separating member for separating said inner cavity of said inner structure into a cooling fluid supply cavity and a cooling fluid collector cavity, said second wall comprising at least one first impingement passage, at least one second impingement passage, and at least one bleed passage; and

seal structure provided within said cooling gap between said first and second walls for separating said cooling gap into first and second cooling fluid impingement gaps, said at least one first impingement passage extending from said cooling fluid supply cavity to said first cooling fluid impingement gap, said at least one bleed passage extending from said first cooling fluid impingement gap to said cooling fluid collector cavity, and said at least one second impingement passage extending from said cooling fluid collector cavity to said second cooling fluid impingement gap such that cooling fluid exits said collector cavity through said at least one second impingement passage and passes into said second cooling fluid impingement gap.

2. An airfoil as set out in claim 1 , wherein said cooling fluid supply cavity being adapted to receive cooling fluid such that the cooling fluid passes from said cooling fluid supply cavity through said at least one first impingement passage into said first cooling fluid impingement gap so as to strike a first section of an inner surface of said first wall, the cooling fluid passes from said first cooling fluid impingement gap through said at least one bleed passage into said cooling fluid collector cavity, and the cooling fluid passes from said cooling fluid collector cavity through said at least one second impingement passage into said second cooling fluid impingement gap so as to strike a second section of said inner surface of said first wall.

3. An airfoil as set out in claim 1 , wherein said separating member comprises a first separating member and said cooling fluid collector cavity comprises a first cooling fluid collector cavity and said inner structure further comprising a second separating member such that said first and second separating members separate said inner cavity of said inner structure into said cooling fluid supply cavity, said first cooling fluid collector cavity and a second cooling fluid collector cavity, wherein only a single cooling fluid supply cavity is provided.

4. An airfoil as set out in claim 3 , wherein said seal structure comprises first seal structure, said at least one bleed passage comprises at least one first bleed passage and said second wall of said inner structure further comprises at least one third impingement passage and at least one second bleed passage.

5. An airfoil as set out in claim 4 , wherein said seal structure further comprising second seal structure within said cooling gap between said first and second walls such that said first and second seal structures separate said cooling gap into first, second and third cooling fluid impingement gaps, said at least one second bleed passage extends between said second cooling fluid impingement gap to said second cooling fluid collector cavity and said at least one third impingement passage extends from said second cooling fluid collector cavity to said third cooling fluid impingement gap.

6. An airfoil as set out in claim 1 , wherein a first distance between said first and second walls within first cooling fluid impingement gap differs from a second distance between said first and second walls within said second cooling fluid impingement gap.

7. An airfoil as set out in claim 1 , wherein said at least one first impingement passage comprises a plurality of first impingement bores or at least one first impingement slot and said at least one second impingement passage comprises a plurality of second impingement bores or at least one second impingement slot.

8. An airfoil as set out in claim 1 , further comprising a plurality of connectors extending between said first and second walls for coupling said first and second walls together.

9. An airfoil as set out in claim 1 , wherein an inner surface of said first wall of said outer structure comprises a rough surface.

10. An airfoil as set out in claim 1 , wherein said outer structure has first and second end sections, and said first wall has first and second end edges, said second end edge of said first wall defines said second end section of said outer structure and said first end edge of said first wall is positioned between said first and second end sections of said outer structure.

11. An airfoil as set out in claim 10 , wherein said inner structure has first and second end sections, at least one first exit passage is defined at least in part by said first end edge of said first wall and said second end section of said inner structure, and at least one second exit passage is defined at least in part by said second end edge of said first wall and said second end section of said inner structure.

12. An airfoil as set out in claim 11 , wherein said at least one first exit passage comprises a plurality of first exit bores or at least one first exit slot and said at least one second exit passage comprises a plurality of second exit bores or at least one second exit slot.

13. An airfoil as set out in claim 11 , wherein said second end section of said inner structure is solid and comprises at least one impingement passage extending through said inner structure second end section and positioned near said at least one first exit passage.

14. A blade for a gas turbine comprising:

a root;

a platform coupled to said root; and

an airfoil coupled to said platform, said airfoil comprising:

an outer structure comprising a first wall;

an inner structure comprising a second wall spaced relative to said first wall such that a cooling gap is defined between at least portions of said first and second walls, an inner surface of said second wall defining an inner cavity, said inner structure further comprising a separating member for separating said inner cavity of said inner structure into a cooling fluid supply cavity and a cooling fluid collector cavity, said second wall comprising at least one first impingement passage, at least one second impingement passage, and at least one bleed passage; and

seal structure provided within said cooling gap between said first and second walls for separating said cooling gap into first and second cooling fluid impingement gaps, said at least one first impingement passage extending from said cooling fluid supply cavity to said first cooling fluid impingement gap, said at least one bleed passage extending from said first cooling fluid impingement gap to said cooling fluid collector cavity, and said at least one second impingement passage extending from said cooling fluid collector cavity to said second cooling fluid impingement gap such that cooling fluid exits said collector cavity through said at least one second impingement passage and passes into said second cooling fluid impingement gap.

15. The blade as set out in claim 14 , wherein said cooling fluid supply cavity being adapted to receive cooling fluid such that the cooling fluid passes from said cooling fluid supply cavity through said at least one first impingement passage into said first cooling fluid impingement gap so as to strike a first section of an inner surface of said first wall, the cooling fluid passes from said first cooling fluid impingement gap through said at least one bleed passage into said cooling fluid collector cavity, and the cooling fluid passes from said cooling fluid collector cavity through said at least one second impingement passage into said second cooling fluid impingement gap so as to strike a second section of said inner surface of said first wall.

16. The blade as set out in claim 14 , wherein said separating member comprises a first separating member and said cooling fluid collector cavity comprises a first cooling fluid collector cavity and said inner structure further comprising a second separating member such that said first and second separating members separate said inner cavity of said inner structure into said cooling fluid supply cavity, said first cooling fluid collector cavity and a second cooling fluid collector cavity, wherein only a single cooling fluid supply cavity is provided.

17. The blade as set out in claim 16 , wherein said seal structure comprises first seal structure, said at least one bleed passage comprises at least one first bleed passage and said second wall of said inner structure further comprises at least one third impingement passage and at least one second bleed passage.

18. The blade as set out in claim 17 , wherein said seal structure further comprising second seal structure within said cooling gap between said first and second walls such that said first and second seal structures separate said cooling gap into first, second and third cooling fluid impingement gaps, said at least one second bleed passage extends between said second cooling fluid impingement gap to said second cooling fluid collector cavity and said at least one third impingement passage extends from said second cooling fluid collector cavity to said third cooling fluid impingement gap.

19. The blade as set out in claim 14 , wherein a first distance between said first and second walls within first cooling fluid impingement gap differs from a second distance between said first and second walls within said second cooling fluid impingement gap.

20. The blade as set out in claim 14 , wherein said at least one first impingement passage comprises a plurality of first impingement bores or at least one first impingement slot and said at least one second impingement passage comprises a plurality of second impingement bores or at least one second impingement slot.