Apparatus and methods for cooling platform regions of turbine rotor blades

1. A platform cooling arrangement for a turbine rotor blade having a platform at an interface between an airfoil and a root, wherein the rotor blade includes an interior cooling passage that extends from the root to at least the approximate radial height of the platform and comprises, in operation, a high-pressure coolant region and a low-pressure coolant region, and wherein, along the side of the platform that corresponds with a pressure face of the airfoil, the platform comprises a topside, which extends from the airfoil to a pressure side slashface, and an underside; the platform cooling arrangement comprising:

an airfoil manifold that resides in the platform, near the junction of the pressure face of the airfoil and the platform;

a slashface manifold that resides in the platform, near the pressure side slashface;

a high-pressure connector that connects the airfoil manifold to the high-pressure coolant region of the interior cooling passage;

a low-pressure connector that connects the slashface manifold to the low-pressure coolant region of the interior cooling passage; and

cooling apertures, the cooling apertures comprising apertures that extend from a starting point along the pressure side slashface to a connection with the airfoil manifold, bisecting the slashface manifold therebetween; and

non-integral plugs that reside in at least one of the following: the cooling apertures, the high-pressure connector; and the low-pressure connector;

wherein the plugs comprise predetermined configurations and placement such that, during operation, a desired flow pattern of coolant through the platform is achieved.

2. The platform cooling arrangement according to claim 1 , wherein the airfoil manifold comprises a first channel formed in the underside of the platform that is enclosed by a first non-integral manifold plate, and the slashface manifold comprises a second channel formed in the underside of the platform that is enclosed by a second non-integral manifold plate;

wherein the first and second manifold plates define the underside of the platform along the first and second channels; and

wherein the high-pressure coolant region of the interior cooling passage comprises an upstream portion of the interior cooling passage, and the low-pressure coolant region of the interior cooling passage comprises a downstream portion of the interior cooling passage.

3. The platform cooling arrangement according to claim 1 , wherein:

the airfoil manifold comprises an arch-like shaped profile that approximately corresponds to the profile contour of the pressure face of the airfoil and resides offset therefrom, the airfoil manifold being offset toward the pressure side slashface;

the slashface manifold comprises an approximate linear shape that is offset slightly from the pressure side slashface, the slashface manifold being offset toward the airfoil; and

the slashface manifold extends axially from an axial position near a trailing edge of the airfoil to an axial position near a leading edge of the airfoil.

4. The platform cooling arrangement according to claim 1 , wherein the airfoil manifold resides just outboard of the underside of the platform and has a longitudinal axis that is approximately parallel to the planar topside of the platform; and

wherein the slashface manifold resides just outboard of the underside of the platform and has a longitudinal axis that is approximately parallel to the planar topside of the platform.

5. The platform cooling arrangement according to claim 3 , wherein the high-pressure connector extends linearly and in an approximate circumferential direction from the pressure side slashface to a junction with the high-pressure coolant region of the interior cooling passage, the linear path of the high-pressure connector being predetermined such that it bisects the slashface manifold and the airfoil manifold before connecting with the high-pressure coolant region of the interior cooling passage;

wherein the low-pressure connector extends linearly in an approximate circumferential direction from the pressure side slashface to a junction with the low-pressure coolant region of the interior cooling passage, the linear path of the low-pressure connector being predetermined such that it bisects the slashface manifold before connecting with the low-pressure coolant region of the interior cooling passage; and

wherein the cooling apertures extend from the pressure side slashface in an approximate circumferential direction along a predetermined path such that each bisects the slashface manifold and then forms a junction with the airfoil manifold.

6. The platform cooling arrangement according to claim 3 , wherein the high-pressure connector extends linearly from a suction side slashface to a junction with the airfoil manifold, the linear path of the high-pressure connector being predetermined such that the high-pressure connector bisects the high-pressure coolant region of the interior cooling passage before connecting with the airfoil manifold;

wherein the low-pressure connector extends linearly from the suction side slashface to a junction with the slashface manifold, the linear path of the low-pressure connector being predetermined such that the low-pressure connector bisects the low-pressure coolant region of the interior cooling passage before connecting with the slashface manifold; and

wherein the cooling apertures extend from the pressure side slashface in an approximate circumferential direction along a predetermined path such that each bisects the slashface manifold and then forms a junction with the airfoil manifold.

7. The platform cooling arrangement according to claim 5 , wherein the high-pressure connector comprises an axial position along the pressure side slashface that approximately coincides with the axial midpoint of the pressure side slashface; and

wherein at least a plurality of the cooling apertures are formed forward of the high-pressure connector and at least a plurality of cooling apertures are formed aft of the high-pressure connector.

8. The platform cooling arrangement according to claim 7 , wherein at least four of the cooling apertures are formed forward of the high-pressure connector and at least four cooling apertures are formed aft of the high-pressure connector.

9. The platform cooling arrangement according to claim 3 , wherein the airfoil manifold and the slashface manifold each comprise a cross-sectional flow area larger than each of the high-pressure connector and low-pressure connector, and each of the high-pressure connector and the low-pressure connector comprise a cross-sectional flow area larger than each of the cooling apertures; and

wherein the cooling apertures comprise varying cross-sectional flow areas that are configured to meter the flow of coolant such that a desired flow pattern of coolant through the cooling apertures is achieved.

10. The platform cooling arrangement according to claim 3 , wherein each of the non-integral plugs comprise one of a full plug and a partial plug, wherein the full plug comprises a plug that is configured to block substantially all of the cross-sectional flow area of the coolant passage in which the full plug is located, and wherein the partial plug comprises a plug that blocks a partial amount the cross-sectional flow area of the coolant passage in which the partial plug is located; and

wherein each of the non-integral plugs comprises one of a slashface plug, which resides along either the pressure side slashface or a suction side slashface of the platform, and a mid-channel plug, which resides in the interior of the platform.

11. The platform cooling arrangement according to claim 10 , wherein each of the cooling apertures, the high-pressure connector; and the low-pressure connector includes one of the slashface plugs; and

wherein the slashface plugs comprise full plugs.

12. The platform cooling arrangement according to claim 10 , wherein the cooling apertures, the high-pressure connector; and the low-pressure connector include slashface plugs;

wherein the slashface plugs comprises partial plugs such that the cooling apertures, the high-pressure connector, and the low-pressure connector comprise slashface outlets;

wherein the partial plugs are configured to provide a predetermined cross-sectional flow area through the slashface outlets;

the predetermined cross-sectional flow area corresponds to a desired coolant impingement characteristic, such that, during operation, the slashface outlets exhaust an impinged flow of coolant against a platform slashface of a neighboring rotor blade.

13. The platform cooling arrangement according to claim 10 , wherein the cooling apertures, the high-pressure connector; and the low-pressure connector include slashface plugs;

wherein the slashface plugs comprises partial plugs such that the cooling apertures, the high-pressure connector, and the low-pressure connector comprise slashface outlets;

wherein the partial plugs are configured to provide a predetermined cross-sectional flow area through the slashface outlets;

the predetermined cross-sectional flow area corresponds to a desired coolant metering characteristic.

14. The platform cooling arrangement according to claim 13 , wherein the high-pressure connector contains a mid-channel plug that is a full plug; and

wherein the mid-channel plug resides between the airfoil manifold and the slashface manifold.

15. The platform cooling arrangement according to claim 13 , wherein the high-pressure connector contains a mid-channel plug that is a partial plug; and

wherein the mid-channel plug, upon installation, is configured to reduce the cross-sectional flow area through the high-pressure connector to a predetermined cross-sectional flow area; and

wherein the predetermined cross-sectional flow area corresponds to a desired coolant metering characteristic.

16. A method of fabricating a platform cooling arrangement in a turbine rotor blade having a platform at an interface between an airfoil and a root, wherein the rotor blade includes an interior cooling passage that extends from the root to at least the approximate radial height of the platform and comprises, in operation, a high-pressure coolant region and a low-pressure coolant region, and wherein, along the side of the platform that corresponds with a pressure face of the airfoil, the platform comprises a topside, which extends from the airfoil to a pressure side slashface, and an underside; the method including the steps of:

forming an airfoil manifold that resides in the platform, near the junction of the pressure face of the airfoil and the platform;

forming a slashface manifold that resides in the platform, near the pressure side slashface;

machining a high-pressure connector that extends linearly and in an approximate circumferential direction from the pressure side slashface to a junction with the high-pressure coolant region of the interior cooling passage, the linear path of the high-pressure connector being machined along a predetermined path such that the high-pressure connector bisects the slashface manifold and the airfoil manifold before connecting with the high-pressure coolant region of the interior cooling passage;

machining a low-pressure connector that extends linearly in an approximate circumferential direction from the pressure side slashface to a junction with the low-pressure coolant region of the interior cooling passage, the linear path of the low-pressure connector being machined along a predetermined path such that it bisects the slashface manifold before connecting with the low-pressure coolant region of the interior cooling passage;

machining cooling apertures that extend in an approximate circumferential direction from the pressure side slashface to a junction with the airfoil manifold, the path of the cooling apertures being machined along a predetermined path such that each bisects the slashface manifold before connecting with the airfoil manifold; and

installing plugs within at least one of the cooling apertures, the high-pressure connector; and the low-pressure connector;

wherein the configurations and locations of the plugs are configured such that a desired flow pattern of coolant through the platform is achieved.

17. The method according to claim 16 , wherein:

the step of forming the airfoil manifold comprises machining a first channel in the underside of the platform and enclosing the first channel with a first manifold plate; and

the step of forming the slashface manifold comprises machining a second channel in the underside of the platform and enclosing the second channel with a second manifold plate;

the first and second manifold plates define the underside of the platform along the first and second channels; and

the high-pressure coolant region of the interior cooling passage comprises an upstream portion of the interior cooling passage, and the low-pressure coolant region of the interior cooling passage comprises a downstream portion of the interior cooling passage.

18. The method according to claim 16 , wherein:

the airfoil manifold is formed to include an arch-like shaped profile that approximately corresponds to the profile contour of the pressure face of the airfoil and resides offset therefrom, the airfoil manifold being offset toward the pressure side slashface;

the slashface manifold is formed to include an approximate linear shape that is offset from the pressure side slashface, the slashface manifold being offset toward the airfoil; and

the slashface manifold extends axially from an axial position near a trailing edge of the airfoil to an axial position near a leading edge of the airfoil.

19. The method according to claim 16 , wherein the airfoil manifold resides just outboard of the underside of the platform and has a longitudinal axis that is approximately parallel to the planar topside of the platform; and

wherein the slashface manifold resides just outboard of the underside of the platform and has a longitudinal axis that is approximately parallel to the planar topside of the platform.

20. The method according to claim 16 , wherein:

the step of forming the airfoil manifold comprises casting a first channel in the underside of the platform and enclosing the first channel with a first manifold plate; and

the step of forming the slashface manifold comprises casting a second channel in the underside of the platform and enclosing the second channel with a second manifold plate;

upon installation, the first and second manifold plates define the underside of the platform along the first and second channels; and

the high-pressure coolant region of the interior cooling passage comprises an upstream portion of the interior cooling passage, and the low-pressure coolant region of the interior cooling passage comprises a downstream portion of the interior cooling passage.

21. The method according to claim 16 , wherein the high-pressure connector comprises an axial position along the pressure side slashface that approximately coincides with the axial midpoint of the pressure side slashface; and

wherein at least a plurality of the cooling apertures are formed forward of the high-pressure connector and at least a plurality of cooling apertures are formed aft of the high-pressure connector.

22. The method according to claim 16 , wherein the airfoil manifold and the slashface manifold each comprise a cross-sectional flow area larger than each of the high-pressure connector and low-pressure connector, and each of the high-pressure connector and the low-pressure connector comprise a cross-sectional flow area larger than each of the cooling apertures; and

wherein the cooling apertures comprise varying cross-sectional flow areas that are configured to meter the flow of coolant such that a desired flow pattern of coolant through the cooling apertures is achieved.

23. The method according to claim 16 , wherein each of the plugs comprise one of a full plug and a partial plug, wherein the full plug comprises a plug that is configured to block substantially all of the cross-sectional flow area of the coolant passage in which the full plug is located, and wherein the partial plug comprises a plug that blocks a partial amount the cross-sectional flow area of the coolant passage in which the partial plug is located; and

wherein each of the plugs comprises one of a slashface plug, which resides along either the pressure side slashface or a suction side slashface of the platform, and a mid-channel plug, which resides in the interior of the platform.

24. The method according to claim 23 , wherein each of the cooling apertures, the high-pressure connector; and the low-pressure connector includes one of the slashface plugs; and

wherein the slashface plugs comprise full plugs.

25. The method according to claim 23 , wherein the cooling apertures, the high-pressure connector, and the low-pressure connector include slashface plugs;

wherein the slashface plugs comprises partial plugs such that the cooling apertures, the high-pressure connector, and the low-pressure connector comprise slashface outlets;

wherein the partial plugs are configured to provide a predetermined cross-sectional flow area through the slashface outlets;

the predetermined cross-sectional flow area corresponds to a desired coolant impingement characteristic, such that, during operation, the slashface outlets exhaust an impinged flow of coolant against a platform slashface of a neighboring rotor blade.

26. The method according to claim 23 , wherein the cooling apertures, the high-pressure connector; and the low-pressure connector include slashface plugs;

wherein the slashface plugs comprises partial plugs such that the cooling apertures, the high-pressure connector, and the low-pressure connector comprise slashface outlets;

wherein the partial plugs are configured to provide a predetermined cross-sectional flow area through the slashface outlets;

the predetermined cross-sectional flow area corresponds to a desired coolant metering characteristic.

27. The method according to claim 23 , wherein the high-pressure connector contains a mid-channel plug that is a full plug; and

wherein the mid-channel plug resides between the airfoil manifold and the slashface manifold.

28. The method according to claim 23 , wherein the high-pressure connector contains a mid-channel plug that is a partial plug; and

wherein the mid-channel plug, upon installation, is configured to reduce the cross-sectional flow area through the high-pressure connector to a predetermined cross-sectional flow area; and

wherein the predetermined cross-sectional flow area corresponds to a desired coolant metering characteristic.

29. A method of fabricating a platform cooling arrangement in a turbine rotor blade having a platform at an interface between an airfoil and a root, wherein the rotor blade includes an interior cooling passage that extends from the root to at least the approximate radial height of the platform and comprises, in operation, a high-pressure coolant region and a low-pressure coolant region, and wherein, along the side of the platform that corresponds with a pressure face of the airfoil, the platform comprises a planar topside, which extends from the airfoil to a pressure side slashface, and an underside; the method including the steps of:

forming an airfoil manifold by machining a first channel in the underside of the platform and enclosing the first channel with a first manifold plate; and

forming a slashface manifold by machining a second channel in the underside of the platform and enclosing the second channel with a second manifold plate;

machining a high-pressure connector that extends linearly and in an approximate circumferential direction from a suction side slashface to a junction with the airfoil manifold, the linear path of the high-pressure connector being machined along a predetermined path such that the high-pressure connector bisects the high-pressure coolant region of the interior cooling passage before connecting with the airfoil manifold;

machining a low-pressure connector that extends linearly in an approximate circumferential direction from the pressure side slashface to a junction with the low-pressure coolant region of the interior cooling passage, the linear path of the low-pressure connector being machined along a predetermined path such that it bisects the slashface manifold before connecting with the low-pressure coolant region of the interior cooling passage; and

machining cooling apertures that extend in an approximate circumferential direction from the pressure side slashface to a junction with the airfoil manifold, the path of the cooling apertures being machined along a predetermined path such that each bisects the slashface manifold before connecting with the airfoil manifold; and

installing plugs within at least one of the cooling apertures, the high-pressure connector; and the low-pressure connector;

wherein the configurations and locations of the plugs are configured such that a desired flow pattern of coolant through the platform is achieved.