Variable-geometry convergent-divergent nozzles

Claim 1

In a variable-geometry convergent-divergent fluid flow nozzle comprising a plurality of variable inclination flaps each of which has an internal face disposed towards the nozzle axis and an external face disposed towards the exterior of the nozzle, and also two lateral edges extending in the longitudinal direction of the nozzle, said flaps being distributed in two rings which are arranged one after the other in the direction of fluid flow so as to afford an upstream ring of flaps and a downstream ring of flaps, with each flap of the upstream ring articulated at its downstream end portion to the upstream end portion of a flap in the downstream ring, each ring of flaps comprising a group of internal flaps and a group of external flaps, the internal and external flaps of each ring being arranged alternately as considered in the circumferential direction of the nozzle and each internal flap being arranged so that portions of the outer face thereof adjacent its lateral edges bear against the internal faces of the two adjacent external flaps, the improvement wherein: a. each internal flap of the upstream ring is articulated to an internal flap of the downstream ring by means of a hinge which extends over the whole circumferential width of the said two flaps, and b. each external flap of one of the two rings is provided adjacent each of its two lateral edges with a recess shaped in such manner as to receive in a substantially sealed manner, the end of the hinge associated with the pair of adjacent internal flaps, said end being arranged to slide in said recess in the circumferential direction of the nozzle when any variation in nozzle flap inclination takes place.