GB744593A - Improvements in or relating to combustion equipment of gas turbine engines - Google Patents

Abstract

744,593. Generating combustion products under pressure. ROLLS-ROYCE, Ltd. Jan. 5, 1953 [Jan. 8, 1952], No. 627/52. Class 51 (1). In combustion equipment of the air-jacketed type for use in gas turbine engines, air inlet means for admitting air to the combustion space comprises a duct or ducts extending along a wall of the flame tube and having at its upstream end an inlet thereto which opens into one of the air passages between the flame tube and the air casing, and having its downstream end extending through an aperture in the flame tube wall to provide an outlet which opens into the combustion space. The cross sectional area of the duct is constant from inlet to outlet so that the velocity of the air flowing in the duct remains constant. The combustion equipment shown in Fig. 1 comprises an annular flame tube having walls 24, 25 disposed in an annular air casing having walls 22, 23, an air inlet section having walls 14, 15 and an outlet section 12 having outer walls 26, 30 and inner walls 34, 35. Fuel injectors 19 are mounted in channel-shaped ends 17c of the wedge-shaped supports 17 which are disposed between aerofoils truts 16. The flame tube comprises primary sections 24a, 25a and secondary sections 24b, 25b and a channel section ring 31 at the upstream end, the ring 31 having apertures to receive the injectors 19. Conical or domeshaped pieces 37 are mounted within the channelsection ring 31 and have apertures in which are mounted axially-but not radially-located bobbins 38 which receive the injectors 19. Apertures 41 are formed in the primary flame tube sections 24a, 25a and patches or scoops 40 are mounted over the apertures to form semi-circular primary air inlet ducts of uniform cross-section. Deflectors 42 are mounted within the scoops so that the inflowing air is turned through an angle of 120 degrees. The metal at the upstream edges of the apertures 41 is bent to form curved lips 43. Corrugated spacers 32, 33 are disposed between the channel-section ring 31 and the primary, sections 24a, 25a and between the primary and secondary sections 24a, 25a and 24b, 25b respectively to permit cooling air flow. Large apertures 36 are formed in the secondary sections 24b, 25b for entry of secondary air. Cooling air may also enter apertures 39 in the channel ring 31 and discharge through spaces between the domes 37 and the corrugated walls of the bobbins 38. In a second embodiment, Fig. 4, the scoops 40 are open at 46 at their downstream ends and air inlets are formed in the scoop by pressing out tabs 45. Tubular members 44 are mounted on the deflectors 42 and lips 43. The fuel injector supports 17 are not wedge-shaped but have fairings 50, 51 which support the channelled ring 52 through members 53, 54. Annuli 55, 56 are supported from the fairings 50, 51 by strips 60 and are spaced from the channelled ring 52 by corrugated elements 57. The invention is also applicable to combustion apparatus comprising an annular air casing containing, a plurality of flame tubes and to apparatus having individual air casings each containing a flame tube.