Aeronautics and astronautics – Miscellaneous
Patent
1993-10-25
1995-04-04
Barefoot, Galen L.
Aeronautics and astronautics
Miscellaneous
244200, 244130, 181213, 60271, B63H 1110, F02K 100
Patent
active
054029643
ABSTRACT:
Apparatus for the interference and manipulation of vortex formation and control of fluid flow to reduce noise and increase flow stability is provided. A specific embodiment is directed to a flexible jet noise suppressor for aircraft, particularly supersonic transport. The jet noise suppressor comprises at least one flexible filament having a length that is about 3 to 10 nozzle diameters. The filament(s) trail behind the nozzle and may be let out for take-off and climb and reeled in while the aircraft is in flight or on the ground. Surprisingly, the use of a single flexible filament eliminates the well-known "screech noise" at about 3,000 Hz and reduces the screech noise by about 50 dB while further reducing the broad band noise up to 15 dB over the entire sound spectrum.
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