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

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Pierre-Yves Bourquin

Philippe Pierre Bouiller

Daniel Germain Kettler

Jean-Pierre Ruis

Fabrice Michel Cot

An axially symmetric turbojet engine exhaust-nozzle includes a system for masking the exhaust jet, such system including inner hot flaps (,), hinging on a conical shell (,) and driven by a first control ring (,) powered by linear actuators (,), and outer cold flaps (,) hinging on an annular assembly (,) and driven by a second control ring (,) powered by linear actuators (,) to vary the angle of the cold flaps. The annular assembly (,) is axially displaceable by a third set of linear actuators (,). Each cold flap (,) comprises an inner skin (,) fitted with orifices (,) and hinging on the annular assembly(,) and an outer skin (,) spaced radially away of the inner skin (,) to define an air flow channel between the skins. When the annular assembly (,) is moved downstream by the third set of linear actuators (,), the outer skins (,) form a scoop introducing fresh air into the cold flaps (,), and said air is injected into the hot gas flow through the orifices (,) in the inner skin and other orifices (,) at the trailing edge (,) of the cold flaps to reduce the exhaust signature.

Turbo jet engine exhaust nozzle with masked gas jet

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).

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Paris, France

Pierre-Yves Bourquin