Noise Generation by Cylindrical Spoilers Immersed in an Air Duct.
Interim technical rept.,
PRINCETON UNIV N J DEPT OF AEROSPACE AND MECHANICAL SCIENCES
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The report describes a study concerned with the effect of thin cylindrical flow spoilers upstream of the exit plane of a constant-area duct on the acoustic power output and directivity patterns of the noise field external to the duct. Spoilers of diameter 116, 532, and 316 in. were placed at 18 in. and 11 in. from the exit plane of a 1 in. diameter duct. Far-field sound pressure levels were measured in an anechoic chamber over a mean velocity range of 250 to 900 fts. The frequency range of the investigation was 200 Hz to 50 kHz, while the Reynolds number range, based on mean velocity upstream of the spoiler and on spoiler diameter, was 8000 to 80,000. Modified author abstract
- Civilian Aircraft