Patent GB-741550-A (GB)
Title: Improvements in or relating to the rotors of multi-stage axial flow compressors or turbines
IPC: F01D5/06
Filed: 1952-07-10
Abstract: 741,550. Shafts. DE HAVILLAND ENGINE CO., Ltd., HALFORD, F. B., and WILSON, W. K. Sept. 21, 1953 [July 10, 1952], No. 17414/52. Class 80(2) [Also in Group XXVI] A rotor for a multi-stage axial flow compressor or turbine comprises two or more axially displaced discs, a one piece tubular torque transmitting connecting piece extending between each pair of discs and rigidly connected thereto but formed separately from at least one of them and having a diameter such that discs extend radially beyond them, each tubular connecting piece being formed at its end or each end formed separately from the disc with a radially extending flange which is located with respect to the disc by a spigot joint and is connected thereto, by bolts or rivets passing through the flange and disc and blades connected to the outer edge portion of each disc outside the connecting pieces. In the arrangement shown, the rotor comprises five spaced parallel discs A, B, C, D and E each having formed integral with it a tubular connecting piece A', B<SP>1</SP>, C', D<SP>1</SP>. Each of the connecting pieces comprises a frusto-conical portion and a cylindrical section A<SP>2</SP>, B<SP>2</SP>, C<SP>2</SP>, D<SP>2</SP>, terminating in a flange A<SP>3</SP>, B<SP>3</SP>, C', D<SP>3</SP>. Each of the discs B, C, D and E has an annular rib forming with the flange A<SP>3</SP>, B<SP>3</SP>, C<SP>3</SP>, or D<SP>3</SP>, a spigot joint and is attached to the appropriate flange by a ring of bolts F. A tubular strut or spacer A<SP>4</SP> formed integral with the disc A is connected to the disc B by a spigot joint A<SP>5</SP> and bolts A<SP>6</SP>. A frusto-conical strut G, also provided to prevent distortion or vibration of the discs, is connected to the discs A and B by spigot joints A<SP>5</SP>, A<SP>7</SP> and bolts A<SP>6</SP>. Similar struts G<SP>1</SP>, G<SP>2</SP> may be provided between the discs C, D and E. A frusto-conical connecting piece H having a series of stepped cylindrical surfaces H<SP>1</SP> is connected to the outer face of the disc E. The disc A is also provided with a tubular extension A' by which it is supported by a bearing A<SP>10</SP>. Each of the discs A, B, C, D, and E has a rim portion A', B<SP>4</SP>, C<SP>4</SP>, D<SP>4</SP>, E<SP>1</SP> which extends beyond the outer surface of the connecting pieces to which rings of rotor blades J, K, L. M, N are connected. Each blade has a forked root which is connected to the rim of the discs by a single pin so that the blade is free to rock to a limited extent so as to reduce the bending stresses in the blade due to centrifugal and gas forces. The various spigot joints between the parts A<SP>1</SP>, B, B<SP>1</SP>, C C', D, D', E, H, G, G<SP>1</SP> and G<SP>2</SP> are so arranged that in operation the loads imposed on the parts by centrifugal forces will tend to cause greater expansion of the male part of each spigot joint than of the female part. Small bleed holes may be provided between the discs to prevent build up of pressure in the spaces between them. The tubular connecting pieces may be formed separately from the discs and are rigidly connected to the discs by spigot joints. The strut members G, G<SP>1</SP>, G<SP>3</SP> may be connected at one or more ends to the discs or may merely make a close fit with appropriate locating surfaces on these discs. The surfaces A<SP>2</SP>, B<SP>2</SP>, C', D<SP>2</SP> and H<SP>1</SP> co-operate with sealing members 0 to 04 carried by the stator. Specification 741,549, [Group XXVI], is referred to.