GB810652A - Improvements in or relating to multi-stage axial-flow compressors and turbines - Google Patents

Abstract

810,652. Turbines. ROLLS-ROYCE Ltd. June 27, 1955 [July 16, 1954], No. 20859/54. Class 110 (3). A multi-stage axial-flow compressor or turbine comprising a central shaft, a plurality of relatively thin cross-section discs carrying blading at their periphery and supported at their centres in axial alignment on the shaft and having axial freedom thereon, the discs inter abutting directly or indirectly over parts spaced radially from the shaft together with means to nip the disc assembly axially by applying an axial tension to the shaft, has one end disc dished with its concave surface directed away from the other discs so that centrifugal forces acting on the end disc in operation tend to place the inter abutting parts of the discs in compression and the second end disc is supported on the shaft by a first annular extending structure through which the disc abuts either directly or indirectly the next adjacent disc and a second annular-extending structure having one end connected to the second end disc and its other end connected with the shaft adjacent the position thereon of the next adjacent disc, the arrangement being such that on operation of the rotor the first annular structure is in compression and the second annular structure is in tension and that the lines of action of the loads therein intersect substantially in the centre plane of the second end disc. The rotor comprises a shaft 10 carrying a number of discs 12a, 12b, 12c, 12d, supporting at their peripheries rows of blades 11. The end disc 12a is dished and has its concave surface directed away from the other discs. This disc is supported on the shaft 10 by splines 14 through a sleeve-like reentrant part 15 as described and claimed in Specification 715,044 and also has an axial flange 18, at a position radially between the shaft 10 and the rim of the disc extending towards the other discs. The end disc 12b is thicker than the remaining discs 12a, 12c, 12d and is overhung from the end of the shaft 10. This disc has an axial flange 22 and a frustoconical flange 23 integral with it the centre lines of which intersect substantially on the centre line of the disc. The flange 22 abuts a flange 20a on the disc 12c and the imier end of the flange 23 is bolted together with a thickened part 24 of the disc 12c to a flange 25 formed on the shaft 10. The centre of mass of the part of the disc 12b shown is arranged to be radially outward of the point of intersection of the centre lines of the flanges 22, 23. The discs 12d are connected to the shaft 10 through splines 14 and re-entrant extensions 21 so as to have axial freedom on the shaft. Spacer members 19 are provided between the discs 12d to engage short axially extending flanges 20 on the discs. The flange 22 may be replaced by a separate spacer member. In a modification, the disc 12c is made similar to the discs 12d and the inner end of the flange 23 is either bolted directly to the flange 25 or surrounds the shaft 10 on the other side of the flange and abuts against it. The whole assembly is placed in compression through spacer members 19 and flanges 20 by tightening bolts 17a, the degree of compression being adjustable by means of a shim 26 inserted between the flanges 16 and 17. The flange 22 may be inclined in the axial direction, in which case the angle between the flange 23 and disc 12c will be increased. The rotor is supported by a stub shaft 10a supported by a bearing 27 mounted in stationary structure 28. Specification 621,418 also is referred to.