GB809268A - Improvements in or relating to turbines - Google Patents

Abstract

809,268. Cooling turbine rotor blades. MASCHINENFABRIK OERLIKON. Nov. 30, 1956 [Dec. 31, 1955], No. 36725/56. Class 110(3). In a turbine in which the roots of the rotor blades are cooled by a coolant which subsequently discharges into the working fluid stream, a throttling constriction is provided in the flow path of the coolant between the blade roots and the point of discharge into the working fluid, the constriction being formed between two rows of rotor blades and a shroud ring carried by a set of stator blades disposed between the rotor blades. The throttling constriction communicates with a channel formed below the roots of the rotor blades through slits formed in or between the roots of the rotor blades. In Fig. 1, two rows of rotor blades 5 are mounted by their roots 6 in axial slots formed at the periphery of the rotor 1, an intermediate spacer 16 being disposed in each slot between the roots of the two blades mounted therein and end rings 14, 15 being disposed adjacent the exposed faces of the blade roots. An axial passage 9 is formed between the lower surfaces of the blade roots 6, the spacer 16 and the bottom of the blademounting slot and cooling fluid such as air is supplied thereto through an opening 20 in the ring 14. The cooling air passes from the passage 9 through slits 8 formed in the blade roots into ducts 10 formed between the lower surfaces of the abutting blade platforms and the outer surfaces of the rotor stubs 1A, the cooling air then entering the annular space formed between the stator blade shroud ring 12 and the spacer 16. The cooling air discharges into the working fluid stream through the annular constrictions 13 formed between the stator blade shroud ring 12 and the blade roots 6. In a second embodiment, the blade roots 24 are mounted in circumferential grooves formed in the rotor 21, annular passages 25 being provided between the lower surfaces of the blade roots and of the blade-mounting grooves. Cooling air is supplied to the passages 25 through radial ducts 27 and flows through slits 23 formed in the blade roots to the annular spaces 26, 19 formed between the rotor blade platforms, the stator blade shroud rings 12 and the surface of the rotor. The cooling air then discharges through annular constrictions 13 into the working fluid stream. Instead of being provided with slits 23, the blade roots of adjacent blades may be spaced apart circumferentially to provide radial passages for the flow of cooling air.