GB1177560A - Jet Nozzle. - Google Patents

Abstract

1,177,560. Jet propulsion nozzles. ROLLS-ROYCE Ltd. Dec.20, 1968 [Dec.28, 1967], No.58860/67. Heading F1J. A jet nozzle comprises a cylindrical member whose downstream end is provided with a plurality of angularly spaced apart, alternately arranged first and second flaps each of whose adjacent pairs of longitudinal edges are inter-connected by a plurality of lobe wall members, there being means whereby the assembly may be moved so as to provide a series of lobes of varying radial depth. The jet nozzle shown comprises a jet pipe 10 at the outlet of which is mounted by means of struts 14 a fixed centre body 16 of doubleconical form. A cylindrical sleeve 20 is mounted on the outer surface of the jet pipe by means of rollers 22 and is movable axially by actuator 21 between a fully retracted position shown in Fig.2 and the positions shown in full lines and chaindotted lines in Fig in which it defines with the centre body a convergent nozzle and a convergent-divergent nozzle respectively. A cylindrical member 24 is mounted externally of the sleeve 20 and is supported by means of rollers 25 within a fixed pod 27, the member being movable axially by means of an actuator 30. Series of flap members 32, 33 are pivotably mounted at the downstream end of the cylindrical member 24 in alternating assembly, the adjacent longitudinal edges of the flaps being interconnected by wall parts 37 which are pivotably connected at 40, the arrangement being such that when the cylindrical member 24 is in its upstream position Fig.1, the flaps 32, 33 are inoperative and are in a substantially cylindrical assembly, but as the member 24 is moved downstream the alternate flaps 33 engage against abutment surfaces 43 on the fixed pod 27 and so are projected inwardly while the intermediate flaps 32 which do not engage against the abutments are moved radially outwardly by the pressure of the jet stream, whereby a lobed nozzle is provided which is effective to silence the jet noise. The side walls of the lobes are formed by interconnected parts 37. In operation at taxi-ing of the aircraft the parts would be disposed as shown in Fig.1, the sleeve 20 defining with the centrebody 13 a convergent nozzle. At take-off when maximum silencing is required, the sleeve 20 would be retracted and cylindrical member 24 extended so as to define a lobed nozzle outlet of maximum radial extent. At subsonic cruise the silencer would be retracted and the sleeve 20 extended to the full line position shown in Fig.1 to define a convergent nozzle, and at supersonic cruise the sleeve 20 would be fully extended to the chain-dotted position Fig.1 in which the parts define a convergent-divergent nozzle.