| 摘要 |
946,995. Turbines. ROLLS-ROYCE Ltd. May 16, 1962 [May 23, 1961], No. 18654/61. Heading F1T. A fluid flow machine has a ring of blades each of which, at its root and at its tip, has a platform which is mounted in a casing for pivotal movement between two extreme angular positions, each platform being of a shape such that in each of the extreme angular positions the platforms of adjacent blades contact each other to prevent fluid from passing between adjacent platforms and thus around the blades, means being provided for effecting pivotal movement of the blades. A gas turbine engine has nozzle guide vanes 15 having platforms 17, 18 with flats 20, 21 of which the flat 20 is of greater length than the flat 21 and is disposed alongside a flat 21 of an adjacent nozzle guide vane 15. The platforms 17, 18 are pivoted in casings 26, 27, sealing of the curved portions 22, 23 being effected by labyrinths 24, 25. Leakage across the vanes 15 is prevented by contact between either the upstream or downstream ends of adjacent flats 20, 21. The casing 27 is spaced from the engine casing 10 by an annular space 30 supplied with compressed air. Pivotal movement of the vanes 15 is effected by a fixed piston 32, forming part of the casing 27, and an axially movable cylinder 33 having an axial annular extension 34. Movement of cylinder 33 is controlled by a two-way valve 40 connected to compartments 35, 36 in cylinder 33, to compressed air in space 30 and to atmosphere. Annular extension 34 has fingers each of which is pivoted to an arm attached to a hollow quill shaft 43 welded to platform 18 of vane 15. In a modification movement of the vanes 15 is effected by pneumatic rams 50, Fig. 6, each having a piston 51 pivoted to an axially extending lever 53 whose downstream end is pivoted to a fixed structure at 54. A ring 55, rotatable circumferentially of the engine has parts 56 through which the levers 53 pass. Blocks 57 on ring 55 are connected by arms 60 to vanes 15. Thus movement of pistons 51 and levers 53 causes rotation of vanes 15. In both embodiments the vanes 15 are cooled by air fed from space 30 through the quill shafts. |
