GB702546A - Improvements in or relating to gas turbine engines - Google Patents

Abstract

702,546. Axial flow compressors ; gas turbine plant. BRISTOL AEROPLANE CO, Ltd. April 10, 1952 [April 18, 1951]; No. 9111/51: Classes 110 (1)'and (3) In a gas turbine plant compressed air bled from the engine before being contaminated by products of combustion, is passed radially inwardly through a first row of hollow compressor stator guide blades and thereafter flows wholly or in part into hollow air intake spider arms and is discharged therefrom either into the airstream flowing into the compressor or into the atmosphere. Air from the discharge of the compressor is led to an annular casing 23, Fig. 2b surrounding the entry end of the compressor from which it passes through holes 39 and the first row of hollow stator guide blades 24 into an annular collecting chamber 40. The chamber 40 forms part of an inner ring 29 which supports the front compressor bearing 12 and an electric generator 42, Fig. 4, driven by the turbine. The generator is covered by a fairing 44 having inner and outer walls 45, 46 and a plurality of internal baffles 47. The air from the chamber 40 passes along the passageways 53, Fig. 2a, into the space 52, Fig. 4, between the inner wall 45 and baffles 47 and returns through the space 49 between the outer wall 46 and the baffles 47 into the passageways 54, Fig. 2a, which alternate with the passageways 53 and passageways 54 are connected by channels 55 with parts 57 forming the leading edge of spider arms connecting the inner and outer rings 29, 30, Fig. 2b. The parts 57 are formed with inner and outer walls 58, 59 between which the air flows to a comnartment 62 which is open to atmosphere through a grid 63. The spider arms 56 also have passages 65, and one or more of these passages are connected to the interior of the fairing 44 so that cooling air for the generator 42 which has entered through the opening 48 may escape to atmosphere. One of these spider arms is used to house the cables from the generator. In the arrangement described, the air does not pass into the airstream flowing into the compressor and a heater may therefore be employed to raise the temperature of the air. In an alternative construction, the outer wall 59 may be formed with a plurality of holes 75 through which the air is fed into the airstream flowing into the compressor. In a further construction the holes are replaced by slots formed between the downstream edges of the wall 59 and the side walls of the arms 56. In a modification air may be discharged from the passage 52 into the interior of the fairing and exhausted to atmosphere through the passageways 65. In a further modification, part of the air from the chamber 40 is led direct to the chamber 54 and another part is passed through the double walls of the fairing 44. The latter part may be discharged directly into the compressor air stream through openings in the fairing 44 or may be used for cooling the generator 42 when the opening 48 is blocked with ice. Each hollow guide blade 24 is supported at its tip and root by trunnions 27, 28 so that the blade is capable of rotation about its longitudinal axis. The trunnion 28 is attached to the guide blade by a sheet metal cap 31 which is brazed or otherwise attached to the trunnion. The trunnion passes through the outer ring 30 and the projecting portion 32 is provided with faces 33, Fig. 3, adapted to receive a spanner 34. By loosening the bolt 36, the blade 24 may be angularly adjusted. A clearance space 37 between the trunnion 28 and outer ring 30 permits differential expansion of the parts. The trunnion 27 is mounted in a parallel bore to allow movement of the blade lengthwise. Specification 702,549 is referred to in the Provisional Specification.