| 摘要 |
1,246,136. Jet propulsion nozzles-variable geometry. ROLLS-ROYCE Ltd. Sept. 12, 1969 [Sept. 14, 1968; Jan.30, 1969], Nos. 43825/68 and 5266/69. Heading F1J. A jet propulsion nozzle is of rectangular crosssection and of convergent - divergent form, the downstream portion comprising four rectangularly disposed walls one of which is supported for movement between a first position in which it co-operates with the remaining three walls to enclose the downstream part and a second position in which the wall is disposed adjacent the upstream part so that one side of the downstream part is open to ambient atmosphere. The nozzle shown comprises a centre-body 39 having upstream and downstream surfaces 34, 41 which divides the nozzle into two convergent - divergent nozzles 31, 40 each in accordance with the invention. The assembly comprises two parallel side walls 35 between which the centre-body 39 extends and upper and lower walls 33 which together with the surfaces 34 of the centre-body define the convergent portions 31. The walls 33 terminate just downstream of the throat 36. Vanes 37 extend between the walls 33 and the centre-body. The divergent portions 40 are defined by upper and lower walls 42 and the surfaces 41 of the centre-body, the walls being mounted for movement between an operative portion A and a retracted portion B see Fig. 2, each divergent portion being open to ambient atmosphere when the wall 42 is in the retracted position. Each wall 42 is of outwardly curved form and is mounted at its two sides in a re-circulating roller bearing 45, see Fig. 5. A bracket member 50 is secured at each edge of the wall 42 and the rollers cooperate with the bracket and with a track member 46 secured to the side wall 38. A cable 60 passing round pulleys 61, 62 is secured to each side of each wall 42 by means of a fitting 63 and the forward pulleys 61 at each side are interconnected by cable 67. A shaft 64 inter-connecting the upper pulleys 61 is drivable by means of an air motor 66 Fig. 3 (not shown) whereby the walls 42 may be moved axially between the operative and retracted portions. Fairing members 80 are provided over the convergent nozzle portions each fairing having extensions 85 which terminate at points 86. When the walls 42 are in the retracted positions ambient air may flow into the wedgeshape spaces 87 which are formed when the pressure in the divergent portions 40 is not significantly above ambient, the outer surface of jet stream being indicated at J 2 .
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