GB1058933A - Improvements in jet propulsion nozzles - Google Patents

Abstract

1,058,933. Boundary layer control. BRISTOL SIDDELEY ENGINES Ltd. Oct: 1, 1964 [Oct. 2, 1963], No. 38830/63. Heading F2R. [Also in Division F1] In a jet propulsion nozzle for an aircraft comprising a jet pipe, at least one flap hinged at its forward end to the jet pipe and having an external surface which is exposed during flight to the free air-stream past the aircraft and an internal surface exposed to flow through the nozzle, there being means for varying the inclination of each flap so as to vary the outlet area of the nozzle, means are provided for discharging gaseous fluid rearwardly over the external surface of at least one of the flaps from a position adjacent the front end of that flap when that flap is inclined to the direction of the free airstream. In a first embodiment, the jet pipe 2 is of circular form and comprises a plurality of adjustable flaps 1 pivotally mounted at the downstream end thereof, each flap comprising an outer member 5 and an inner member 6 which are hinged together at 7. The outer member 5 is formed with an extension 8 which is pivotally mounted on a bracket 9 integral with a wall 26 of the manifold 11 which forms part of the wall of the jet pipe 2. The member 5 is formed at its upstream end with a part cylindrical surface which co-operates with a corresponding surface formed on the wall 26, the cylindrical surface of the flap member 5 co-operating with the downstream end of the jet pipe wall to form an orifice 15 through which air or gas under pressure may be discharged from the manifold 11, the flow of air or gas along the outer surface of the flap member preventing breakaway of air flow over that surface. The inner flap member 6 is connected to the bracket 9 by a radius arm 17 and is connected to a sleeve 18 which is movable axially so as to adjust the angular position of the flap. The sleeve 18 carries rollers 22 mounted on pins 21, the rollers engaging in cam slots 29 formed in a cam ring 23 which is rotatable angularly by means of a motor 25 driving through gearing 24, 28. A valve 27 controlling flow of air or gas under pressure into manifold 11 is also driven by the cam ring 23 so that as the flap is moved inwardly, so the valve is opened to allow air or gas under pressure to flow into the manifold and so through orifice 15 across the outer surface of flap member 5. The cam ring is supported by rollers 30. The forward edge of the flap member 5 may be tapered in thickness so that the orifice defined thereby is of variable width. In Fig. 9 the jet pipe is of rectangular form being defined by upper and lower walls 50, also by end walls not shown. The propulsion nozzle is defined by a centre body 57 and by partitions 58, also by adjustable flaps which comprise a forward portion 54 hinged to the jet pipe at 53 and by a rearward portion 55 hinged to the forward portion at 56. A slot 52 is formed between the end of the jet pipe walls 50 and the upstream ends of the flap members 54 through which air or gas under pressure may be discharged.