GB950288A - Improvements in nozzles for aircraft propulsion - Google Patents

Abstract

950,288. Jet propulsion plant. BRISTOL SIDDELEY ENGINES Ltd. Aug. 18, 1960 [Aug. 18, 1959], No. 28222/59. Heading FIJ. A jet pipe and adjustable nozzle assembly, in which the jet pipe passage is rectangular in sections transverse to the direction of flow and comprises two opposite walls which are substantially flat and parallel to one another, has a dilating aerofoil structure spanning the jet pipe passage between the flat walls so as to divide the flow into two streams and those parts of the other walls of the jet pipe which lie opposite the flank surfaces of the dilating aerofoil are each articulated by at least two hinge joints extending transversely to the flow direction, actuating mechanism being provided for the articulated wall parts whereby the surfaces presented by the wall parts towards the dilating aerofoil may be varied from concave to convex. A dilating aerofoil structure is stated to be a hollow structure of biconvex, sharp trailing edge, aerofoil shape in planes parallel to the parallel walls of the jet pipe, the structure walls being simultaneously adjustable in opposite directions to vary the thickness of the aerofoil shape. The jet pipe 1 is defined between two opposite flat and parallel side walls 2 and two opposite top and bottom walls 3a, 3b each of which comprises a fixed part 4a, 4b and an articulated part 5a, 5b. The articulated parts 5a, 5b, each comprise a first flap 7a, 7b and a second flap 8a, 8b connected together by hinge joints 9a, 9b, the first flaps being pivoted to the fixed walls 4a, 4b by hinges 10a, 10b. A dilating aerofoil structure 11 comprising fixed tubes 14, 15 on which are hinged respectively a pair of leading flaps 16a, 16b and a pair of trailing flaps 17a, 17b. The flaps are slightly convexly curved in the region of their free edges. The transverse plane of the maximum thickness of the aerofoil structure 11 is arranged to pass through the hinge joints 9a, 9b, so that when the pairs of flaps 7a, 8a and 7b, 8b are moved inwards to present generally convex surfaces towards the structure 11, throats are formed in this transverse plane. The dilating aerofoil may be collapsed inwards to increase the throat area and reduce the divergence of the exit passages. The flaps 7a, 8a and 7b, 8b may be also moved outwards so that the throats move rearwards to a plane through the trailing edges of the flaps 8a, Sb. The flaps 7a, 7b are moved by actuators 18a, 18b and the flaps 8a, 8b by trapezoidal linkwork 19a, 19b and actuators 20a, 20b. The actuating mechanism for the dilating aerofoil structure comprises pairs of crank arms 22a, 22b and 23a, 23b connected by links 24a, 24b, 25a, 25b to the flaps 16a, 16b, 17a, 17b and operated by actuators 30, 31. The side walls 2 are hollow and accommodate the actuators 18a, 18b, 30, 31. These walls serve to supply pressure air through passages 33 into the dilating aerofoil structure to balance the pressures acting on the flaps. A diaphragm 34 divides off the trailing edge compartment 35 which is vented to atmosphere. Flaps 36a, 3b are hinged to the fixed walls parts 4a, 4b and connected to the trailing ends of the flaps 8a, 8b by links 38a, 38b. Holes 40 admit pressure air from the hollow walls 2 to balance the pressures on the flaps. The invention is described with reference to a ram jet having combustion equipment 41,42,43. The hollow wall structure 43 is provided with slits 44 through which air passes to provide film cooling. The wall 43 is constructed as described in Specification 930,782. The heat shielding with discharge slits may be provided in the walls 2, the flaps 7a, 7b, 16a, 16b. Means for controlling the operation of the flaps under the control of Mach number, altitude and manual means is also described.