GB836117A - Improvements in or relating to combustion equipment for gas-turbine engines - Google Patents

Abstract

836,117. Generating combustion products under pressure. ROLLS-ROYCE Ltd. Feb. 4, 1957 [Feb. 2, 1956], No. 3381/56. Class 51 (1). Combustion equipment of a gas turbine engine comprises a flame tube disposed within an outer air casing, a fuel injector being provided to inject fuel into the upstream end of the flame tube. The flame tube has at each side of the local centre line of the combustion space air inlet means adapted to direct into the combustion space a plurality of streams of air having a component of velocity in an upstream direction to meet in the region of the local centre line, the air streams from each respective side of the local centre line being directed to meet at a point short of the local centre line so as to produce an air stream which is flattened in cross-section to reduce the risk of this air stream missing the flattened air stream from the air inlet means on the opposite side of the local centre line. The combustion equipment shown comprises an annular flame tube 24, 25 disposed within an outer annular air casing 22, 23, a fuel injector 20 being disposed within the upstream portion of the flame tube 14, 15 and injecting through an aperture 21 in a ring member 17, the flanges 17a, 17b of which are spaced from the walls of the flame tube by corrugated spacers 18, 19. Pairs of U-shaped scoop members 31, 34 in nested relation are disposed on the outer surfaces of the flame tube walls, the scoops facing into the air streams flowing between the flame tube and outer air casing. The scoop members 31 are curved at their downstream ends to enter orifices formed in the flame tube wall sections 24a, 25a, the adjacent portions of the flame tube wall sections being curved inwardly at 33. A curved tubular member 36 is disposed within each scoop member 34 and extends through an opening in the flame tube wall section 24a, 25a. The air streams from each pair of scoops converge at a point which lies short of the local centre line 30 of the combustion space. The air streams from the scoops at each side meet adjacent the centre line. The cross-section through the scoops in this embodiment is constant whereby velocity of the air streams remains constant. In a second embodiment, annular scoops are disposed on the outer surfaces of the flame tube walls, the crosssectional area of the scoops increasing in the direction of air flow. Short pipes directed in an upstream direction lead from openings formed in the flame tube wall at the downstream end of each scoop, the air streams from each pair of pipes converging at a point short of the local centre-line of the combustion space. The invention is also applicable in the case of combustion equipment comprising tubular flame tubes disposed either each in its own tubular air casing or a plurality thereof disposed in an annular air casing. Specifications 744,593, 744,657 and 744,659 are referred to.