Apparatus for cooling a bucket assembly

A rotor assembly comprising:

• a shaft;
• a plurality of bucket assemblies, the bucket assemblies disposed circumferentially about the shaft and coupled to the shaft, each of the bucket assemblies comprising a platform, an airfoil extending radially outward from the platform, a shank extending radially inward from the platform, and a dovetail extending radially inward from the shank, the dovetail configured to couple the bucket assembly to the shaft, the shank including a pressure side sidewall, a suction side sidewall, an upstream sidewall, and a downstream sidewall, the sidewalls at least partially defining an internal cooling circuit, the cooling circuit configured to receive a cooling medium from the dovetail and provide the cooling medium to the airfoil, the upstream sidewall at least partially defining an interior cooling passage and at least partially defining an exterior ingestion zone, the cooling passage configured to provide a portion of the cooling medium from the cooling circuit to the ingestion zone of an adjacent bucket assembly through an opening of the cooling passage defined in one of a pressure side surface or a suction side surface of the upstream sidewall.