GB800491A - Improvements in or relating to turbine rotors for gas-turbine engines - Google Patents

Abstract

800,491. Turbine rotors for gas turbine engines. ROLLS-ROYCE, Ltd. Dec. 14, 1955 [Dec. 24, 1954], No. 37430/54. Class 110 (3). A turbine rotor disc structure for a gas turbine engine for carrying a row of rotor blades comprises at least three disc members, the members being secured together in the form of a stack, at least the two end disc members being of dished frusto-conical form over at least the inner part of their radius. The disc members are formed with a first series of abutment surfaces adjacent their inner radius and with a second series of abutment surfaces between their inner radius and their outer periphery, first and second bolting means being provided to clamp the disc members together over their abutment surfaces. The number of discs is such that if in service, one disc should fail, the load to which the other discs would be subjected would be unlikely to cause them to fail. The rotor shown is a two-stage turbine rotor of a gas turbine engine and comprises a high-pressure rotor structure 11 and a low-pressure rotor structure 12, each of the rotor structures comprising assemblies of five disc members 11a ... 11e and 12a ... 12e respectively. The discs each have a central aperture 13, an axiallythickened portion 14 adjacent the aperture, an axially-thickened portion 16 outwardly of the portion 14, and an axially-thickened rim 15 formed with slots in which the blade roots are mounted. The high-pressure rotor discs are in addition formed with axially-thickened portions 19 intermediate the thickened portions 14, 16. The centre discs 11c and 12c of the two rotor disc structures are of plane form while the remaining discs are of frusto-conical form between the axially-thickened portions 14 and 16. The highpressure rotor discs are secured together and to a flange on the main shaft 10 by means of a ring of bolts 20, some of the bolts 20a also passing through a flange 29 on a ring 30, the flange 29 being cut away in the way of the remaining bolts 20b. The high-pressure rotor discs are also secured together and to the flange 32 of a ring member 33 by means of a ring of bolts 21. The low-pressure rotor discs are similarly secured together and to the flanges 31 and 36 on the ring members 30 and 33 by means of rings of bolts 22, 23. The bolts 20b, 22b and 23b which do not pass through the flanges on the ring members 30 and 33 hold the discs together upon assembly and dismantling. Cooling fluid such as air enters the space 40 around the tubular member 41 and flows through the spaces 37, 38 between adjacent rotor discs, finally escaping into the working fluid stream. The axially-thickened portions 14, 16 and 19 may be either annular lands or series of circular bosses.