GB1418077A - Variable-geometry convergent-divergent nozzles for jet propulsion engines - Google Patents

Abstract

1418077 Jets propulsion nozzles - variable geometry SOC NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION 17 April 1973 [17 April 1972] 18335/73 Heading F1J The invention relates to a variable geometry convergent-divergent propulsion nozzle for a jet engine in which it is possible to vary simultaneously the nozzle throat section and the outlet section. The nozzle assembly shown in Fig. 1 comprises a jet pipe 4, 10 at the downstream end of which is pivotally mounted at 21 a plurality of convergent nozzle flaps 20 at the downstream end of each of which is pivotally mounted at 31 a divergent flap 30, each convergent flap and its associated divergent flap constituting a pair of flaps. Associated with each pair of flaps 20, 30 is fixed structure comprising a pair of circumferentially-spaced members 14a, 14b to which the convergent flaps 20 are pivotally mounted at the points 21, each convergent flap being integrally formed with a pair of links 20x to which the piston-rod 24, 22 of a hydraulic actuator 25 is pivotally connected at the point 23. The divergent flap 30 is integrally formed with a pair of links 30x to which is pivotally connected at the point 33 one end 32c of a link 32 which is bifurcated at its other end 32a, 32b, the ends 32a, 32b being pivotally mounted at a point 34 to the fixed members 14a, 14b. As the convergent flap 20 pivots about the point 21 so the pivot point 33 of the divergent flap 30 pivots about the point 34. In a second embodiment Fig. 5, bifurcated link 132 connecting the pivotal point 33 of the pair of links 30x integral with the divergent flap 30 and the pivotal point 34 on the fixed structure 14a, 14b is of extensible form. The forked portion of the link is indicated at 132a, 132b and the stem at 132c, the stem comprising a cylinder 132cy and a piston 132cx the piston and cylinder being loaded by a spring so that the stop 150 on the piston-rod is in abutment with the stop 151 on the cylinder. Stop members 160, 161 are provided on the convergent and divergent flap members 20, 30. In the maximum area position Fig. 5 the link 132 is of minimum length with the stops 150, 151 in abutment, and the stops 160, 161 on the flaps are spaced apart. As the convergent flap is pivoted inwardly about point 21, the link 132 remains of minimum length until the stops 160, 161 on the flaps come into abutment. Further inward movement of the flaps causes the link 132 to extend but the flaps 20, 30 do not move relatively to each other.