GB1316452A - Gas turbine engine - Google Patents

Abstract

1316452 Gas turbine engines DEFENCE SECRETARY OF STATE FOR 5 Aug 1971 [14 Aug 1970] 39173/70 Heading F1G A gas turbine engine comprises a rotor member, a shaft to which the rotor member is connected and which is supported in bearings which allow freedom for axial thermal-expansion of the shaft, the rotor member being spaced from a sealing member supported in static structure at a first radial plane of the engine by an axial sealing clearance, and the shaft being mounted on a member which is located in static structure at a second radial plane of the engine, the member being made of a material having a lower coefficient of thermal expansion than the shaft. In the by-pass gas turbine engine shown, the H. P. compressor rotors 7 are connected to the rotor of the H. P. turbine 13 by a shaft 14 supported by roller bearings 15, 16 which permit axial displacement due to thermal expansion. Endwise location of the shaft 14 is effected by a tubular member 20 which is attached to the shaft by a coupling 23 at a position between the rotors 7 and the rotor 13 and is located at its upstream end by a ball bearing 21. The member 20 is of a material having a lower co-efficient of thermal expansion than that of the shaft 14, whereby axial movement of the turbine rotor 13 relative to adjacent parts of the casing is reduced, so that a closer clearance between sealing members 17, 19 can be maintained. For the purpose of maintaining the temperature, and therefore the thermal expansion, of the member 20 at an accurately known value, air at a known temperature is bled from the compressor and supplied to the space 31 between the member 20 and a surrounding tube 32. Similarly, the portion of the engine casing surrounding the combustion chamber 11 may be of double-walled construction 40, 41 to provide an annular space 44 supplied with air at known temperature bled from the compressor. This air is exhausted via holes 45, 46 into the by-pass passage 5 or may instead be used for cooling hot parts of the turbine. The outer wall 40 is of the same low expansion material as the member 20, while the inner wall 41 is anchored at its downstream end and supports the stator of the H.P. compressor 6 through a sliding joint 43. To provide sealing where the burners 10 pass through the walls 40, 41 despite relative thermal expansion between the walls a sleeve 60 is screwed into a threaded aperture in the wall 41 and a cup 61 is dispersed between a shoulder 62 on the sleeve and the wall 41. The cup can slide axially relative to the sleeve and radially relative to the outer casing.