GB1131883A - Gas turbine engine - Google Patents

Abstract

1,131,883. Gas turbine engines; axial-flow compressors. ROLLS-ROYCE Ltd. April 20, 1967. No. 18304/67. Headings F1C, F1G and F1T. A gas turbine engine comprises a rotatable assembly mounted in a thrust bearing with freedom of limited axial movement, the rotatable assembly having a part with a substantially axially facing surface which defines with fixed structure a chamber to which fluid under pressure from the fluid-flow duct is supplied, and a variable flow restriction which is variable in response to axial movement of the rotatable assembly controls the pressure in the chamber. In the gas turbine engine shown, air is bled from the delivery end of the compressor 11 via one or more apertures 32 and supplied via an axial labyrinth seal 33 to a chamber 31 formed between a turbine rotor disc 15 and a fixed wall 27. The air escapes from the chamber 31 via a radial labyrinth seal 30 and enters the turbine flow duct downstream of turbine nozzle guide vanes 26; the rate of flow of air can be arranged to be adequate for cooling purposes. Axial displacement of the shaft 16 due to inbalance between the end thrusts of the compressor 11 and the turbine 13 varies the flow restriction presented by the seal 30 and therefore varies the air pressure within the chamber 31 in the sense which opposes the inbalance. The outer race 22 of thrust bearing 20 is loaded by one or more springs 25 or hydraulically actuated pistons to provide a substantially constant axial load on the bearing. Instead of being applied to a turbine rotor disc 15, the invention may be applied to a compressor rotor disc.