Abstract: An internal flow mixer is attached to the rearward end of a turbofan engine for inverting the engine fan and core streams. Rearwardly of the internal flow mixer is a multi-lobed exhaust nozzle which mixes ambient air with the gases flowing from the flow mixer. An ejector housing lined with acoustic absorption material receives the flow from the exhaust nozzle and discharges the thrust producing gases in noise abatement condition.

Abstract: A noise suppressor for use with a turbofan engine, the suppressor being formed of a tubular exhaust shroud affixed to the engine exhaust end, the shroud providing an internal circumferential surface, a flow mixture affixed to the engine exhaust end, an elongated centerbody supported within the exhaust shroud and having an external cross-sectional area less than the internal cross-sectional area of the shroud providing an annular area through which thrust producing exhaust gases of the engine pass, acoustic lining affixed to a substantial portion of the internal circumferential area of the exhaust shroud in the portion thereof receiving the centerbody, and acoustical lining affixed to a substantial portion of the exterior area of the centerbody in the area thereof received within the exhaust shroud so that thereby the thrust producing gases pass through an area of reduced channel height. A substantial portion of the annular area through which the gases pass is encompassed by acoustical lining.

Abstract: A noise reduction system for a jet engine including a tubular exhaust shroud affixed to the engine through which engine exhaust gases pass, porous acoustical lining affixed to a substantial portion of the internal circumferential surface of the shroud, a chamber in contact with the acoustical lining outer surface and a controllable source of air pressure affixed to the chamber to control the passage of air through the acoustical lining to thereby vary the acoustical absorption properties of the lining.

Abstract: A noise suppression system for use with a jet aircraft engine having a plug support cylinder affixed to the engine, a tubular ejector shroud affixed to the engine and encompassing the plug support, the shroud having a reduced internal diameter adjacent the aft end and a plurality of spaced apart blow-in openings formed circumferentially about the shroud forward end providing passageways for the entrance of ambient air from the exterior to the interior of the shroud. A blow-in door is secured to the shroud for opening and closing each of the blow-in openings. A translating plug is supported on the plug support cylinder and is positionable between a forward position and an aft position and forms an annular exhaust nozzle between the exterior of the plug and the interior of the aft end of the shroud. A daisy mixing nozzle is positioned within the shroud aft of the blow-in doors, the nozzle being configured of a plurality of lobes providing undulating interior and exterior surfaces.