GB571658A - Improvements in or relating to turbines having overhung rotors - Google Patents

Abstract

571,658. Elastic-fluid turbines. BUCHI, A. March 1, 1943, No. 3352. Convention date, May 23, 1942. [Class 113 (iii)] The motive fluid, which may be hot gases, passes tangentially from inlet blades 6 into the blades 17 of an overhung rotor 1, and exhausts into a diffuser 22. Four, or two, fluid inlet pipes 4, are separated by spiral blades 15. Gas leaves the rotor and enters the diffuser at a pressure which is lower than the pressure at the exit end' of the diffuser. The rotor blades may be integral with the rotor, and thickened towards the hub. The diffuser hub 24 may be integral with the rotor and the diffuser may curve away at right angles to the rotor. To couple together the casing parts 4, 7, which, otherwise might move relatively due to unequal heat expansion, keys 27 are provided. Cooling of the blades is secured by vanes 28 on the back of the rotor, cooling air being drawn from a space 29 fed either by the atmosphere, or from a casing 9 supplied by a blower B. The vanes 28 have a disc 31. Holes 32 lead to the rotor blades 17 ; notches may also be provided in the rotor periphery or air may flow over the disc periphery. Sealing means 33, 34, may be incorporated, the space 35 in between communicating with the atmosphere, or the exhaust 23 through a pipe 36. In a modified arrangement, two inlet ports 4, only, are provided. The exit edges 20, of the blades 17, are cut off obliquely, and the innermost diameter of the diffuses is smaller than the extreme diameter of the outer exit edges 20. The hub of the rotor, tapering forward into the diffuser, is cooled internally. The exit angles of the blades at their inner and outer diameters, are designed so that the relative gas velocities (rotor peripheral speeds to absolute gas velocities) are substantially equal to each other, and to the absolute gas velocities. The flow into the inner edge of the diffuser is axial, and that at the outer edge produces a vortex, to convert velocity into pressure energy with the least loss.