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Theoretical Modeling of High‐Speed Helicopter Impulsive Noise

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A simple theoretical model of high‐speed helicopter impulsive noise, based on the Ffowcs Williams and Hawkings theoretical formulation, is developed. The model depends primarily on the large scale features of the rotor's aerodynamic flow field. For acoustic radiation near the rotor's tip‐path‐plane, monopole, dipole, and quadrupole sources all contribute—with the monopole term dominating for high subsonic advancing tip Mach numbers (Mat). Predicted pulse shapes show good agreement with experimental data below Mat = 0.9 and poor agreement above. Predicted peak amplitudes show generally poor agreement, becoming worse as Mat approaches 1.0. Several methods of improving theory‐data correlation are suggested.

Document Type: Research Article


Affiliations: Aeromechanics Laboratory, U.S. Army Aviation R&D Command, Ames Research Center, Moffett Field, California, U.S.A.

Publication date: January 1, 1979

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  • The Journal of the American Helicopter Society is the world's only scientific journal dedicated to vertical flight technology. It is a peer-reviewed technical journal published quarterly by AHS International and presents innovative papers covering the state-of-the-art in all disciplines of rotorcraft design, research and development. (Please note that AHS members receive significant discounts on articles and subscriptions.)

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