An aircraft engine has a nozzle shaped to reduce the volume of Mach diamonds being formed in the exhaust plume. A notch or recess is formed in the discharge edge of the nozzle. The recess provides a forward discharge edge that causes additional Mach diamonds to occur at a regular spacing from the forward discharge edge. These additional Mach diamonds are axially staggered with other Mach diamonds, which occur at regular spacing from the rearward edge of the nozzle discharge edge. Each Mach diamond has a volume that is substantially less than one-half the volume of a Mach diamond created by a conventional nozzle. This results in less high temperature areas per axial increment in the plume than the prior art exhaust plumes. Because Mach diamonds are the primary cause of high infrared emissions, as well as acoustic noise, a reduction in the total volume of Mach diamonds in the exhaust plume thus reduces infrared emissions, as well as the noise.

The present invention generally relates to providing an improved jet mixer noise suppressor for high speed jets that rapidly mixes high speed air flow with a lower speed air flow, and more particularly, relates to an improved jet mixer noise suppressor that uses feedback of acoustic waves produced by the interaction of sheer flow instability waves with an obstacle downstream of the jet nozzle.

The present invention generally relates to providing an improved jet mixer noise suppressor for high speed jets that rapidly mixes high speed air flow with a lower speed air flow, and more particularly, relates to an improved jet mixer noise suppressor that uses feedback of acoustic waves produced by the interaction of sheer flow instability waves with an obstacle downstream of the jet nozzle.

A shrouded nozzle arrangement for a gas turbine engine exhaust comprises a shrouded nozzle and duct means. The exhaust nozzle is translatable from a first position, wherein the exit plane of the nozzle lies upstream of the exit aperture of the shroud, to a second position, wherein the exit plane of the exhaust duct lies substantially downstream of the exit aperture of the shroud. In this second position, the use of reheat or thrust vectoring may be used without damage to the shroud.

A noise reduction kit is provided for installation on a bypass turbine engine having a core engine, an outer casing and a thrust reverser. The kit comprises a mixer downstream of the core engine for mixing fan air of the engine with the exhaust gas from the core engine to reduce the peak velocity of the exhaust gas; a structure for supporting and positioning said mixer relative to the engine; a spacer for extending the length of the exhaust gas flow path between said mixer and the thrust reverser to permit sufficient mixing of the fan air with the exhaust gas prior to reaching the thrust reverser; and an acoustic tail pipe assembly configured to define an outlet area for the engine exhaust gas flow path. The outlet area is sized and shaped to reduce pressure loss in the exhaust gas stream in an amount necessary to compensate for the pressure increase in the exhaust gas stream created by the mixer.