GB813399A - Improvements in and relating to blading and shrouding arrangements in axial flow elastic fluid turbines - Google Patents

Abstract

813,399. Turbine diaphragm structures. ALLEN SONS & CO. Ltd. W. H., OXFORD. J. T. B., and POOLE, E. J. March 22. 1957 [March 26, 1956], No. 9355/56. Class 110 (3). In an axial-flow, elastic-fluid turbine, stationary shroud means surrounding the tips of the rotor blades is supported from the outer periphery of the stator blading whereby it may expand and contract independently of the turbine casing, the stator blading being supported by a diaphragm structure and arrangements being provided for circulating cooling fluid about the diaphragm structure. The gasturbine shown in Fig. 1 comprises a rotor disc 1 carrying rotor blades 16, the rotor blades being surrounded by a stationary shroud ring 17 which is supported from the stator blades 2. The stator blades 2 are formed at their inner and outer ends with platforms 7, 11 respectively, the platforms being formed with radiallyprojecting flanges 8, 12 respectively. The flanges 8 are supported by means of bolts 9 in a recess 6 in the diaphragm 3, the diaphragm being located at its inner periphery upon the housing 4 of a bearing in which the rotor shaft 5 is mounted. The flanges 12 on the outer platforms 11 bear against a face 13 extending inwardly from the stator casing 15, and the stator shroud ring 17 which is in the form of segments is attached to the flanges 12; alternatively the segments of the shroud ring may be formed integrally with the flanges 12 or with the platforms 11. A sheet metal member 18 is secured to the upstream side of the diaphragm 3 to provide a, passage for the flow of cooling air. In Fig.,2, the stator shroud ring 23 surrounding a row of rotor blades mounted on a rotor 22 is secured in recesses formed in the outer platforms 27 of stator blades 21 disposed on either side of the rotor blade row by means of keep members 25 secured by riveting to the outer surface of the shroud ring and which engage the projections 24 of the platforms 27. The stator blades are supported on the diaphragms 30 and have flanges bearing against the stator casing as in the first embodiment. A pair of sheet metal members may be disposed adjacent the upstream and downstream faces of the diaphragm (Fig. 3, not shown), cooling air being admitted from the rotor into the space between the pair of members at the upstream side of the disc, the cooling air flowing radially outwardly through this space, then radially inwardly through the space between the inner sheet metal member and the upstream face of the diaphragm. The cooling air then flows through apertures in the diaphragm and radially outwardly adjacent the downstream face of the diaphragm, finally discharging into the working fluid stream.