GB790854A - Improvements in or relating to axial-flow fluid machines - Google Patents

Abstract

790,854. Elastic-fluid turbines. ROLLSROYCE, Ltd. Nov. 23, 1955 [Dec. 16, 1954], No. 36521/54. Class 110 (3). In a stator construction for an axial-flow fluid machine such as a turbine of an aircraft gas-turbine engine, of the kind including a plurality of guide vanes having inner and outer mounting platforms by which the vanes are mounted in stator structure, means are provided to secure the inner vane platforms together in an annular assembly. The means comprises a pair of annular members which are clamped together to grip the inner platforms between them, the annular members interlocking with the upstream or downstream edges of the vane platforms or with both said upstream and downstream edges. An outer casing is disposed around the vanes in spaced relation to the outer vane platforms and interengaging radially-extending features on the outer platform and outer casing serve to locate the outer platforms circumferentially. An axially-extending annular member encircles the vanes between the vanes and the casing and is engaged by its upstream edge in an axiallyfacing annular groove in the casing and by its downstream edge in axially-facing grooves in .the outer platforms of the vanes adjacent their downstream edges. The two-stage gas turbine shown comprises rotor blades 10, 11 mounted on rotor discs 12, 13 respectively, inlet nozzle guide vanes 14 and inter-stage guide vanes 16. The inlet nozzle guide vanes 14 are formed with inner and outer vane platforms 19, 26 respectively, the upstream and downstream edges of the inner platform 19 being formed with notches which engage radial dogs 24, 23 formed on the annular member 20, the downstream edge also being formed with a hook portion 22 which is received in an axially-facing channel formed in the annular member 20. A second annular member 21 is bolted to the annular member 20 so as to clamp the vane platforms 19 therebetween. The outer vane platform 26 is formed with dogs 27, 30 at its upstream and downstream edges, the dogs engaging notches 28, 31 formed on the outer casing 29. An annular member 33 of frusto-conical form engages by its upstream edge a groove 34 in the outer casing 29 and by its downstream edge grooves 32 formed in the outer vane platforms 26. The inter-stage guide vanes 16 are mounted in a similar manner, the inner vane platform 39 being grooved to receive flanges 42, 45 on the pair of annular members 40, 41, the members 40, 41 being clamped together by bolts 47, distance pieces 46 being interposed between the members. A member 50 forming part of a labyrinth seal between the two rotor discs 12, 13 is also clamped between the members 40, 41. Co-operating dogs 43, 44 are provided on the vane platforms 39 and the upstream annular member 40. The outer vane platform 51 of the guide vane 16 is formed with dogs 52, 55 which engage notches 53, 56 formed in the outer casing 29 and an annular frusto-conical member 58 engages an annular groove 59 formed in the casing 29 and in grooves 57 formed in the outer platforms 51. A fixed shroud ring 35 around the rotor blades 10 is formed with a T-flange 36 which engages grooves 26a in the platforms 26 and 38 formed in the outer casing 29. The downstream edge of the shroud member 35 is received in grooves in the upstream edges of the outer vane platforms 51. A fixed shroud ring 60 around the rotor blades 11 engages by means of a flange 62 with grooves 61 in the outer vane platforms 51, by lugs 63 in a groove 64 in the outer casing 29, and by lugs 65 in a groove in the outer casing. Lugs 67 at the downstream edge of the shroud ring 60 engage dogs 66 formed on the casing 68 of the exhaust assembly.