GB808655A - Improvements in or relating to multi-stage axial-flow compressors - Google Patents

Abstract

808,655. Axial-flow compressors; gas turbine plant. ROLLS-ROYCE Ltd. Nov. 9, 1955 [Nov. 22, 1954], No. 33823/54. Classes 110 (1) and 110 (3). A multi-stage axial-flow compressor comprises a tubular structure carrying stator blades and having an exterior circumferential flange intermediate its ends; a cylindrical outer casing of high-strength material secured at one end to the flange and extending downstream from the flange to surround that part of the tubular structure which extends downstream of the flange, thereby to define an annular chamber externally of the tubular structure; and a diffuser structure spaced radially inwards from and supported from the outer casing at a position downstream of the outlet end of the tubular structure, the outlet end of the tubular structure being slidably supported by the diffuser structure. In the compressor shown, forming part of a gas turbine engine, the stator blades 12 are carried by an upstream part 13 of the casing and by a downstream inner part 15. The parts 13, 15 are supported from the outer air casing wall 60 of the combustion equipment by a downstream outer casing part 16 which is connected to the wall 60 by bolts 61 and has swellings 20 at which it is attached by bolts 22 to flanges 18, 19 on the casing parts 13, 15. Locating dowels 21 may be of oval form, as described in Specification 715,086, to allow for differential thermal expansion between the part 13, which is of light alloy such as aluminium alloy or magnesium alloy, and the parts 15, 16, which are of steel, nodular cast iron or other ferrous alloy, or titanium alloy. Streamlined radial struts 31 are attached by bolts 59 to the casing part 16 and welded to annular sheet metal diffuser walls 24, 25 at flanged openings in the walls. A ring 26 is welded to the wall 25 and has a sliding engagement at 29 with the casing part 15. Conical members 40, 41, 45, 46, bolted to rings 38, 37, 27 welded to the wall 24, support a shaft bearing 42 and seals 44, 47, 49. Cooling air for the bearing 42 is supplied through the centre of the compression shaft 43 and flows around the bearing by way of holes 50, 51, 52. Air leaking from the high-pressure end of the compressor past the labyrinth seal 47 flows through holes 53 and thence through apertures formed between the member 41 and the scalloped flange 39 of ring 37 into the struts 31, and thence through holes 56 into an annular manifold defined by an annular baffle 54 and part-annular baffles 55 which extend between the struts 31. An outlet union (not shown) on the outside of casing part 16 allows the leakage air to be tapped off for cooling the turbine. The space forward of the baffle 54 forms an annular manifold connected through holes 30 to the compressor outlet; an outlet union may be attached to a facing 66 to permit highpressure air to be tapped off for anti-icing, cabin pressurization or operating an air turbine to drive auxiliaries. The casing parts 13, 15 may be made in one piece from steel or other high-strength metal with an external bolting flange between the ends of the piece for connection to the part 16.