GB1170255A - Combustion Apparatus. - Google Patents

Abstract

1,170,255. Gas turbine combustion chambers; jet propulsion plant. ROLLS-ROYCE Ltd. June 27, 1967 [July 1, 1966], No. 29673/66. Headings F1J and F1L. Combustion apparatus comprises a grid of longerons provided at one end with a nose member in alignment with the adjacent ends of the longerons and shaped to allow substantially laminar flow past it, the nose member having means for providing selectively a sheltered zone for pilot combustion. By the term "longeron" is meant a member extending longitudinally of the grid and whose length is several times greater than its width. The longerons 30 are mounted in a curved duct 19, Fig. 2, communicating at the upstream end with an annular plenum chamber 18 fed with by-pass air from the low-pressure compressor (12) of a gas turbine vectored thrust engine, Fig. 1 (not shown). The duct 19 leads to a swivelling propulsion nozzle 20. Adjacent longerons 30 in the grid are spaced apart to provide slots therebetween, the grid having a compound curvature to follow the bend 35 and the cylindrical portion 33 of the duct wall. A nose member 31 at the leading ends of the longerons 30 has an arcuate chamber 42 which can be supplied with bleed air from the highpressure compressor (13) and an arcuate pipe 44 which can be supplied with liquid fuel. When additional thrust is required from the nozzle 20, valves are opened so that air and fuel flow through facing ports 43, 45 from chamber 42 and pipe 44 respectively into an arcuate recess 46. The fuel/ air mixture leaves the recess as an arcuate curtain providing stabilization for pilot combustion of the mixture in zone 52. An igniter is provided in the latter zone. Main fuel is delivered through pipes 48, 49, 50 to fuel injectors 51 disposed in the slots between adjacent longerons 30. The grid defines with the wall portion 35 a convergent passage 36 so that some of the air entering the passage from the annular chamber 18 flows through the slots between the longerons to mix with fuel from the injectors 51. The slots are shaped as shown in Fig. 4 to produce a more uniform flow. The grid is supported in the duct 19 by a pin 39 engaging a hollow vane 38 and by spaced supports 37, the remainder of the air from passage 36 flowing past the latter supports after cooling the wall 35. A guide vane 55 may be provided to prevent flow separation from the inner wall 47 of the bend. In a modification, the nose member of the grid is formed by a pair of plates hinged at their upstream ends along a transverse axis to provide a stabilizer of adjustable V-shape.