Abstract: In a turbine having closed-circuit steam-cooling passages about the rim of the rotor during steady-state operation, compressor discharge air is supplied to the rotor bore for passage radially outwardly into the wheel space cavities between the wheels and spacers. Communicating slots and channels in the spacers and wheels at circumferentially spaced positions enable egress of the compressor discharge air into the hot gas flow path. At turbine startup, cooling air flows through the closed-circuit steam passages to cool the outer rim of the rotor while compressor discharge air pre-warms the wheels and spacers. At steady-state, cooling steam is supplied in the closed-circuit steam-cooling passages and compressor discharge air is supplied through the bore and into the wheel space cavities to cool the rotor.

Abstract: A rotor cooling circuit includes a cooling medium supply reservoir for supplying cooling medium to a plurality of axial passages through the turbine wheel and spacer disc rims. A passageway communicates cooling medium from the reservoir for flow in series and in a serpentine manner in and about the cavities between the wheels and discs. The flows are reunited at a plenum for flowing the cooling medium into first and second stage buckets. Return passages through the rims of the wheels and spacer discs return spent cooling medium from the buckets to a return location external of the rotor. Transition elements between the buckets and spacer plates in the rotor rim accommodate any thermal mismatch between the adjoining buckets and spacer plates to prevent cooling medium leakage at the joints.