A note on the radiative directivity patterns of duct acoustic modes

✍ Scribed by G.F. Homicz; J.A. Lordi

• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 417 KB
• Volume: 41
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1016/s0022-460x(75)80175-1

✦ Synopsis

The classical solution for the external radiative pattern of acoustic modes in an unflanged circular duct has been presented in a form more suitable for practical computations. This expression predicts the same locations for the principal lobe and zeroes as would be obtained from the baffled model, and has the added advantage of being able to predict sideline and aft radiation. Simple rules for locating the principal lobe and zeroes, involving only hand calculations, are presented and shown to correlate well with sample computer .. calculations of the full exlSression for the large azimuthal mode numbers typical of modern turbofans.