GB842677A - Improvements relating to gas turbine engines - Google Patents

Abstract

842,677. Generating combustion products under pressure. GENERAL MOTORS CORPORATION. May 9, 1958 [May 28, 1957], No. 14885/58. Class 51 (1). [Also in Group XXVI] In a gas turbine engine having an axial flow compressor, the combustion system comprises a cylindrical casing which contains a ring of separate flame tubes each of circular cross-section at the upstream end and the diffuser which connects the compressor outlet to the combustion system comprises a ring of separate diffuser passages each having an inlet in the shape of a sector of an annulus and a circular outlet and each coaxial with one of the flame tubes, the upstream end of each flame tube being so arranged that the cross-sectional area of the flow path between a fuel nozzle at the centre of the inlet dome of the flame tube and the outlet edge of the diffuser passage, that is a surface of revolution generated by rotation about the flame tube axis of a line joining the fuel nozzle and outlet edge, is between one and a half times and twice that of the diffuser passage outlet. In the engine shown, the combustion equipment comprises inner and outer cylindrical casings 36, 29 between which is disposed a ring of separate flame tubes 31 each having a conical upstream end wall 32 and fuel injector 42. The compressor outlet passage 10 is formed between cylindrical walls 11, 12 and connects with a similar passage 16 formed by walls 18, 19 having straightener vanes 17. The outlet 16 is connected to a ring of separate diffuser passages 22 each having an inlet 23 in the shape of a sector of an annulus and an outlet 24 of substantially circular shape, the passages being disposed so that the inlets 23 together form a substantially annular inlet. The outlet ends of the passages are supported by a partition-plate 26 having a series of apertures 27, one for each passage 22. Air discharging from each passage 22 diverges in a conical flow path, the area of which is the area of the surface of revolution generated by an element 33 which represents the shortest distance between the perimeter of the outlet 24 and the fuel injector 42. In order to provide a substantially uniform reduction in pressure through the diffuser passage 22 to the entrance to the space around the flame tube, the area of the surface of revolution 33 must be between one and a half times to twice the area of the outlet opening 24. A baffle-plate 47 is disposed within the flame tube downstream of inlet openings 46 in the end wall 32. Air inlets to the flame tube are also provided at 51, 52; interconnector pipes 44 are provided between flame tubes.