Gerald B Herman

US Patent:

41379926, Feb 6, 1979

Filed:

Dec 30, 1976

Appl. No.:

5/755836

Inventors:

Gerald T. Herman - Seattle WA

Assignee:

The Boeing Company - Seattle WA
Aeritalia S.p.A. - Naples

International Classification:

F01N 100

US Classification:

181213

Abstract:

Core noise, a low frequency noise component believed to be partly caused by the combustion processes within the engine, and turbine noise, a higher frequency noise component caused by the interaction of high velocity gases with the engine's turbine, are attenuated by noise absorbing structures that are disposed within the engine's nozzle and that in part define the physical geometry of the nozzle duct. The nozzle is formed of an outer sleeve and an inner generally bulb-shaped plug which are coaxially arranged to define an annular nozzle duct that channels the flow of gases rearwardly from the outlet of the engine's turbine. The plug has a hollow interior that is partitioned into a plurality of cavities that communicate with the nozzle duct via perforations provided in an outer wall of the plug. The size, shape and positioning of the interior cavities and outer plug wall perforations are selected so as to absorb noise energy existing in the exhaust gases, both at the relatively low frequencies characteristic of core noise and at the relatively higher frequencies characteristic of turbine noise.