GB779059A - Improvements in or relating to axial-flow fluid machines, for example compressors orturbines of gas-turbine engines - Google Patents

Abstract

779,059. Turbine and compressor rotors. ROLLS-ROYCE, Ltd. July 11, 1955 [July 15, 1954], No. 20723/54. Class 110 (3). A bladed rotor of an axial-flow turbine or compressor comprises a disc 21 having mounted on the rim 20 thereof a plurality of blades 22 each having a blade platform 23, a shouldered root portion 24 which engages a channel 26 formed in the disc rim and a circumferentiallynarrow stem 25 between the platform and the root portion. According to the invention, a substantially flat member of fully circular ring form is mounted and retained on the rim of the disc and is of such radial dimension as to extend outwards to the blade platforms, the ring member engaging the disc rim and the adjacent axially-facing end surfaces of the blades thereby blanking off at least some of the spaces between the blade stems. Such ring members may be provided at both the upstream and downstream sides of the rotor disc. In a first embodiment, Figs. 1, 2, 4, 5, ring members 28, 29 are provided respectively at the upstream and downstream sides of the blade stems. The platforms 23 of alternate blades are formed with inwardlyfacing grooves 31, and the periphery of the ring member 28 is formed with circumferentiallyspaced dogs 30 which are engaged in the grooves 31 by rotational movement of the ring member. The rim of the rotor disc is formed with inwardly-projecting flanges 36, 44 and the flanges are formed with spaced lugs 35, 43. The inner periphery of the ring member 28 is formed with an axial flange 33 having radially-projecting dogs 34 at its end, the dogs 34 being engaged behind the lugs 35 on the disc rim by the circumferential movement of the ring member. The ring member 29 engages in a similar manner with the blade platforms and the disc rim. The ring member 28 is prevented from circumferential movement by bolts 37. A number of keys 45 having heads 46 and tangs 48 pass between the bottoms of the blade roots and the bottoms of the blade-mounting slots 26, and the tangs 48 pass through holes 49 in the ring member 29 and are then bent outwardly to engage the member 29 which is thereby locked against circumferential movement. A circumferential groove 50 is formed in the disc rim and is supplied with coolant through apertures 51. The coolant is caused to flow only to alternate spaces 27 between the blade stems by means of blanking pieces 52, the coolant flow being as indicated by the arrows 57, Fig. 7. The coolant flows through passages in adjacent blades and returns to the other spaces 27 and finally discharges through openings in the downstream ring member 29. In a second embodiment, Fig. 10, ring members 68, 69 at the upstream and downstream sides of the rotor disc 63 are secured by means of key members 70 which pass between the bottoms of some blade roots and the bottoms of the corresponding blade-mounting slots in the rotor disc rim. The keys pass through apertures in the ring members 68, 69, the head 71 on the key engaging the upstream member 68, and a tang 72 on the key being bent after assembly to engage the downstream ring member 69. The ring members may be located by means of annular flanges 74 on the rotor disc rim, and tabs 73 secured to the ring members may engage notches cut in the flanges 74. In a third embodiment, dogs formed on ring members are engaged behind lugs formed on the rotor disc rim as in the first embodiment and circumferential movement of the ring members is prevented by means of channel-section key members mounted on the axially-extending flange of a ring member between co-operating dogs and lugs, the key member being prevented from disengagement by means of a locking piece located between the key member and the rotor disc, the locking piece having tangs at its ends which are bent to engage the key member so as to locate the locking piece with respect to the-key. Specification 663,386 is referred to.