GB599829A - Improvements relating to the construction of turbine rotors - Google Patents

Abstract

599,829. Gas turbines. POWER JETS (RESEARCH & DEVELOPMENT), Ltd., and McLEOD, R. C. June 8, 1945, No. 14632. [Class 110 (iii)] An overhung rotor comprises two bladed discs 13, 16, Fig. 2, and an intermediate unbladed disc 21. The disc 13 has a flanged hub by which it is secured upon the turbine shaft 7. Shoulders 24 on the disc 21 have a shrink fit with annular projections on the discs 13, 16 and the discs 16 and 21 are supported by this means alone. The discs are held together axially by a nut on the extension 15 of the hub of the disc 13 and the construction provides complete annular spaces 18, 20 between the hubs of the discs 13, 16. Toothed flanges 25, 26 on the discs provide driving engagement. The rim of the disc 21 provides a floor 27 opposite the stator blading 6 and this rim may have radial slits as described in Specification 593,918. A rotor may be similarly built up of more than two bladed rotors and the final bladed rotor 42, Fig. 3, may be secured to a tail shaft 46 by means of a ring 47 of triangular cross-section and an annular flange 45 of the rotor 42. The disc 16, Fig. 2, is made selfsupporting in relation to centrifugal load and the discs 13, 16 take part of the centrifugal load of the disc 21. The support afforded to the latter is augmented by off-setting outwardly the mass centres of the discs 13, 16, thereby producing, under running conditions, a centrifugally induced bending moment acting upon the shoulders 24. High-pressure cooling air is led to the hollow shaft 7 and passes through holes 19 to annular spaces 18, 20 and through holes 23 to annular spaces 28, 29. Thence, it passes between the teeth 26 and through channels beneath the blade roots. Cooling air is led also by passages 38 to a space between disc 13 and a stationary wall 33 and from the shaft 7 by passages 19 and 37 to a space 36 between disc 16 and a stationary wall 34. The tail-shaft bearing of shaft 46, Fig. 3, is carried in a housing 41 supported by radial tubes 50 and stiffened by a tubular extension 52 and diagonal struts 53. Cooling air from the hollow shaft 7 passes into the housing 41 and through the tubes 50 and struts 53.