Bucket assembly cooling apparatus and method for forming the bucket assembly

1. A bucket assembly comprising:

a platform, the platform defining a platform cooling circuit configured to flow cooling medium therethrough;

an airfoil extending radially outward from the platform; and

a lower body portion extending radially inward from the platform, the lower body portion defining a root and a cooling passage extending from the root, the cooling passage configured to flow cooling medium therethrough, the platform and lower body portion further including a ligament between the cooling passage and the platform cooling circuit, the cooling passage providing a direct line-of-sight from a base of the root through the cooling passage and the ligament to the platform cooling circuit, the ligament defining a bore hole extending through the line-of-sight between the cooling passage and the platform cooling circuit.

2. The bucket assembly of claim 1 , wherein the ligament defines a plurality of bore holes.

3. The bucket assembly of claim 1 , wherein the cooling passage includes a protrusion, the protrusion providing the line-of-sight from the root through the ligament to the platform cooling circuit.

4. The bucket assembly of claim 1 , wherein the platform and the lower body portion include a plurality of cooling passages.

5. The bucket assembly of claim 4 , wherein the ligament defines a plurality of bore holes.

6. The bucket assembly of claim 5 , wherein at least one of the plurality of bore holes is configured to flow cooling medium from at least one of the plurality of cooling passages to the platform cooling circuit, and wherein at least one of the plurality of bore holes is configured to flow cooling medium from the platform cooling circuit to at least one of the plurality of cooling passages.

7. The bucket assembly of claim 1 , the platform further defining an exhaust passage, the exhaust passage configured to exhaust cooling medium from the platform cooling circuit adjacent the platform.

8. The bucket assembly of claim 1 , wherein the lower body portion includes a shank and a dovetail, the dovetail defining the root.

9. A method for forming a bucket assembly, comprising:

forming the bucket assembly in a mold, the mold including a platform cooling circuit core and a body cooling circuit core, the bucket assembly comprising:

a platform, the platform defining an interior platform cooling circuit formed by the platform cooling circuit core;

an airfoil extending radially outward from the platform; and

a lower body portion extending radially inward from the platform, the lower body portion defining a root and an interior cooling passage extending from the root, the interior cooling passage formed by the body cooling circuit core and configured to flow cooling medium therethrough, the platform and lower body portion further including a ligament between the interior cooling passage and the interior platform cooling circuit; and

after forming the bucket assembly in the mold, forming a bore hole in the ligament between the interior cooling passage and the platform cooling circuit;

wherein the cooling passage provides a direct line-of-sight from a base of the root through the cooling passage and the ligament to the interior platform cooling circuit.

10. The method of claim 9 , wherein forming the bore hole requires no exterior modification of the bucket assembly.

11. The method of claim 9 , wherein the bore hole extends through the line-of-sight.

12. The method of claim 9 , wherein the body cooling circuit core includes a protrusion core, and wherein the interior cooling passage includes a protrusion formed by the protrusion core, the protrusion providing the line-of-sight from the root through the ligament to the interior platform cooling circuit.