Societe Nationale D'etude Et De Construction De Moteurs D'aviation

Fabrice Michel Cot

Philippe Pierre Bouiller

Daniel Germain Kettler

Jean-Pierre Ruis

Pierre-Yves Bourquin

Guy J-l Lapergue

A gas-flow exhaust assembly for a jet propulsion system of an aircraft in which a converging exhaust nozzle (4) is fitted with translating cold flaps (21, 22). The primary exhaust nozzle (4) comprises two hot-flaps (5, 6) situated beyond a primary duct (1) enclosed by an aircraft fairing (2). The fairing (2) is extended by a secondary exhaust nozzle (20) which is supported by the primary duct (1) and which is translatable by a control mechanism (27a, 27b). The secondary exhaust nozzle (20) comprises cold flaps (21, 22) which are driven by another control mechanism (29a, 29b) independently of the angular positions of the hot flaps (5, 6). Preferably, there are two eyelid-shaped cold-flaps (21, 22) hinging and supported on horizontal transverse shafts (23a, 23b). The shafts (23a, 23b) are preferably affixed on two lateral slides (24a, 24b) which slide on the primary duct (1) and are displaceable by the control mechanism (27a, 27b) which translates the secondary exhaust nozzle (20).

Converging exhaust nozzle fitted with translating cold flaps

A variable geometry exhaust nozzle for a turbojet engine is disclosed having an array of outer flaps and an array of inner flaps radially spaced apart and extending about a central axis of the exhaust duct structure. The array of outer flaps comprises a plurality of outer flaps each having an upstream end pivotally attached to the engine duct structure. The array of inner flaps comprises a plurality of upstream inner flaps, each having an upstream edge pivotally attached to the engine duct structure and a plurality of downstream inner flaps each having an upstream edge portion pivotally attached to a downstream edge portion of a corresponding upstream inner flap. A control annulus is movably attached to the engine structure so as to be movable axially along the central axis and is connected to an actuator which moves the control annulus between upstream and downstream limit positions along the central axis. The control annulus is connected to the upstream and downstream inner flaps such that the axial components of the forces exerted by the control annulus on the connections to the upstream and downstream inner flaps extend in opposite directions. The control annulus is also connected to the outer flap such that the axial component of the force exerted by the control annulus on the outer flap during flap movement extends in the same direction as does the axial component of the force exerted by the control annulus on the upstream inner flap connection. Since the axial components of the forces are in opposite directions, the actuator need only exert a minimal force on the control annulus to vary the positions of the flaps.

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Savigny-Le-Temple, France

Fabrice Michel Cot