GB644031A - Improvements in or relating to gas turbine engines - Google Patents

Abstract

644,031. Gas turbine plant. BRISTOL AEROPLANE CO., Ltd. June 16, 1947, No. 15812. [Class 110(iii)] [Also in Group XII] In a gas turbine plant of the type having an annular combustion chamber consisting of a pair of concentric, generally cylindrical walls enclosing a number of axially extending flame tubes, the nozzle guide vane assembly comprises at least two sector members each comprising a group of guide vanes integral with an inner and an outer vane carrier of which the latter is secured to the turbine casing, the outer wall of the combustion chamber is removably secured to the compressor and turbine casings, and the inner wall of the combustion chamber is secured to the compressor casing and to the inner vane carriers of the sector members. Both of these walls constitute load-carrying members whereby the turbine casing is supported from the compressor casing or viceversa. The duct casing 18, Fig. 2, forming the discharge of the compressor is connected to the turbine nozzle guide vane assembly 23 through the inner and outer walls 21, 22 of the annular combustion chamber 19. The outer wall 22 is in three ring-like parts, an inlet part 24, a central part 25 and an outlet part 26. To ensure uniformity of air supply around the flame tubes, inner and outer baffles 28, 29, Fig. 3, are provided. These baffles also prevent overheating of the walls 21, 22 by forming with these walls passages 34, 35 which are fed with cooling air through openings. 37, 43 by the compressor. The baffles 29 are attached to the central part 25 of the outer wall by bolts 45. When it is desired to inspect the flame tubes, the bolts 45 and the bolts attaching the part 25 to the parts 24, 26 are removed and the part 25 slid lengthwise. The part 44 of one or more of the baffles may then be slid lengthwise so that its left-hand end leaves the' fork, whereupon it may be raised outwardly and entirely removed. The flame tubes are attached to the inlet part of the outer wall 24 by a boss 42 integrally formed with a thin walled casting 51. The fuel supply pipe 57 passes through the boss 42. The exit 65 of the flame tube is arranged at a short distance 67, 68 from the nozzle guide vane assembly 23 so as to allow the cooling air from the passages 34, 35 to mix with the hot combustion gases. The cooling air being at a higher pressure than the gases prevents leakage through the openings 67, 68. The outer wall 22 which is connected to the compressor discharge casing 18 and outer shroud ring of the nozzle guide vane assembly 23 is adapted to constitute part of a stress bearing member, the other elements of which are the compressor casings and the shroud ring. When the part 25 is removed the loads transmitted through this part have to be transmitted elsewhere. For this purpose the inner wall 21 is bolted to the casing 18 and welded to a ring carried by the diaphragm 69. The casing 18 has also bolted to it a diaphragm 71, and the diaphragms 69, 71 carry roller bearings 72, 73 supporting the shaft 74. The diaphragm 69 engages pistonwise with a ring 76 of the guide vane assembly 23, a piston ring seal 77 being provided between the two. The guide vane assembly 23 comprises a plurality of guide vanes 78 integrally formed with an inner and outer carrier 79 and 80 respectively. A group of blades 78 together with the carriers 79 and 80 constitute a sector member. Fig. 5, a number of which are mounted end-to-end around the assembly to form a complete ring of blades. The sector members are supported by the inner and outer rings of the guide vane assembly 23 so that each is free to expand and contract in an outward radial or circumferential direction relatively to each other and relatively to the guide vane rings. The inner carriers 79 of each sector member are held to the inner ring of the assembly 23 by being clamped between two annular plates. and the outer carriers 80 are spaced radially from the outer ring 83 of the assembly and from each other by gaps 84. The carriers 80 are slotted as at 85 to receive the head 86 of a pin 87, the shank of which enters a hole in the ring 83. At two diametrically opposite points of the assembly 23, two bolts 88 are screw-threaded into the outer ring 83 so that the end faces 89 enter and accurately fit radial holes 90 at the bottom of the slots 85. When the bolts 88 are screwed home the ring 83 is rigidly connected with inner ring of the assembly 23. Specifications 624,768, 624,842 and 625,790 are referred to.