GB947795A - Improvements in or relating to axial flow multi-stage compressors - Google Patents

Abstract

947,795. Axial-flow compressors; compressor blades fixing. ROLLS-ROYCE Ltd. April 24, 1962 [April 27, 1961], No. 15367/61. Headings F1C and FIT. An axial-flow multi-stage compressor which may form part of a gas turbine jet propulsion engine has a compressor casing 10 (Fig. 2) which comprises an outer wall 17 (Figs. 2 and 3) and an inner wall 18 which is radially spaced from the outer wall by a number of axially spaced circumferentially extending ribs or rings 19 and one or more rows of stator blades 25, each blade passing through an aperture in the inner wall 18 and having a root portion 25a at its radially outer end, which portion contacts the inner surface of the outer wall 17 or of a part 17a interposed between the inner surface and the root portion 25a, the outer surface of the inner wall 18 and surfaces on a pair of the ribs or rings 19. The upstream and downstream rings 19 are respectively secured against relative rotation to the air intake casing 20 and a steel ring 21 carried by combustion equipment 12, by dowel pins 22. The casing 10 is split axially into two semi-circular portions at each of the ends of each of which there is located an axially extending wall 23 having provision for dowel pins 24. The semi-circular casing portions are secured together, the upstream ring 19 is secured to the intake casing 20, and the downstream ring 19 is secured to the steel ring 21 by axially extending strips 26, an annular strip 27 and an annular strip 28 respectively, all strips 26, 27, 28 being of a thermo-setting synthetic resinous material, such as glass or asbestos fibres impregnated with phenolic or epoxy resin, bonded to the outer wall 17. Preferably, a narrow gap is left between the semi-circular portions so that the strips 26 may be cut through without damaging these portions. The inner and outer walls 18, 17, rings 19, walls 23 and semicircular or part-circular strengthening bands 17a are preferably of thermo-setting synthetic resinous material. Corrugated strengthening strips, for example of aluminium may be provided between the walls 17, 18. Ports 29 and 30 and grooves 31 allow access of the air to the spaces between the walls 17, 18 to pressure-balance the inner wall 18 so that any hoop stress is absorbed by the outer wall 17. In an alternative construction, Fig. 6, the walls 23 are provided with tongues and grooves (not shown) instead of dowel pins 24, and the outer wall 17 is provided with flats 34, adjacent the join between the two semicircular casing portions, for receiving axially extending securing strips 38 formed of a number of layers, for example, twenty-three, of a thermosetting resin material bonded to the flats 34. Apertures 29, 30 are not provided and the spaces between the walls 17, 18 are filled with a filling material 40.