Patent GB-1009776-A (GB)
Title: Supersonic jet propulsion nozzle
Inventor: COLVILLE FRANCIS JEFFREY
IPC: F02K1/09
Filed: 1964-08-25
Abstract: 1,009,776. Jet propulsion nozzles. ROLLS-ROYCE Ltd. Aug. 25, 1964, No. 34817/64. Heading F1J. A supersonic jet propulsion nozzle has a substantially cylindrical nozzle casing assembly and a bulbous plug mounted therein, the plug and casing assembly being relatively movable axially to permit the throat of the nozzle to be disposed either in a position at the downstream end of the casing assembly or in a position upstream of said downstream end, whereby the nozzle may be employed either as a convergent or as a convergent-divergent nozzle, and silencing means for substantially increasing the peripheral area over which the jet gases mix with the ambient air. A gas turbine jet propulsion engine supersonic nozzle 19, Fig. 2, comprises a nozzle casing having an axially slidable cylindrical outer-portion 22 and a fixed inner portion 23. A bulbous plug 25 is supported within the nozzle casing by struts 26 attached to upstream plug portion 30. Casing portion 22 is slidable between positions shown in full and dotted lines to define respectively with plug 25 a convergent or a convergentdivergent flow passage, the throat remaining at 24. Plug portion 30 is attached to a downstream portion 31 by a tube 32 upon which slide sleeves 42, 50. Sleeve 42 is moved by a rod 43 driven by rack and pinion 44, 45 and is pivotally connected by links 38 to a series of pivoted "fingers" 33, 34 forming the central surface of plug 25, such that axial movement of the sleeve causes radial movement of fingers 33, 34 and a variation in the nozzle throat area. Sleeve 50 is pivotally linked to a series of angularly spaced flaps 52, each pivoted on a fixed central portion of plug 25 intermediate each pair of fingers 33, 34, such that axial movement of the sleeve causes flaps 52 to move into or out of the jet stream. In the position shown dotted flaps 52 increase the peripheral area over which the jet stream mixes with ambient air to effect silencing of the nozzle. Outward movement of flaps 52 is accompanied by inward movement of fingers 33, 34 to compensate for the reduction in flow area of throat 24. In a modification, Fig. 4, an axially slidable nozzle casing portion 100 surrounds a plug 103 supported by struts 105, 106 from fixed casing portion 101 so that the nozzle can be set to convergent or convergent-divergent form, as in the previous embodiment. A series of angularly spaced aerofoil members 113 are pivoted at 115 within the plug outer casing 112 and can be moved into the jet stream at the throat 102 by movement of ram actuated sleeve 117 so as to reduce the throat flow area. A series of angularly spaced vanes 107 extend radially from plug 103 at throat 102. Each vane 107 comprises, Fig. 6, a fixed upstream portion 131 and a downstream portion consisting of two pivoted separable parts 132, 133. Actuation of a push rod 134 by way of a ram 147, slidable sleeve 145 and related linkwork causes parts 132, 133 to move to the dotted line position in which ambient air is admitted between parts 132, 133 to mix with the jet stream and effect silencing.