GB1432262A - Jet propulsion efflux ducts - Google Patents

Abstract

1432262 Jet propulsion nozzles BRITISH AIRCRAFT CORP Ltd 25 Jan 1974 [1Feb 1973] 5185/73 Heading F1J The invention relates to a jet propulsion discharge duct in which a plurality of blades 4 project radially inwardly from the wall of the duct, each blade being disposed or capable of being disposed at an angle of incidence to the gas flow such that each blade produces at least one vortex in the flow, the blades being so arranged in groups that the - combined effect of the vortices is to modify the cross-sectional shape of the gas flow rearwardly of the duct outlet. The discharge duct 3 shown has twelve blades 4 pivotally mounted adjacent the outlet, the blades being disposed in four groups 5, 6, 7, 8 each comprising three blades 4, the groups being disposed symmetrically at either side of the vertical plane III-III. Each blade is movable by means of an actuator 9 whereby it may be set in line with the gas flow or at an inclination thereto such that it causes formation of vortices in the gas flow. The blades of groups such as 5 and 6 are arranged to create oppositely rotating vortices. in Fig. 4 the blades are pivotally mounted each about an axis 10, 10 which is inclined to a longitudinal axis X', X'; each blade is movable between a retracted position in which it is disposed within a recess 11 in the wall of the duct and an operative position in which it extends radially into the duct at such an angle as to create vortices in the gas flow. In a further embodiment Fig. 5 the discharge duct 2a opens into a down-stream portion 12, the vortex-producing blades 4 or 4a being mounted in the portion 12.