Acoustic scattering of rotorcraft noise

Seongkyu Lee, James P. Erwin, Kenneth Steven Brentner

Research output: Contribution to journalConference article

5 Citations (Scopus)

Abstract

The scattering of helicopter rotor noise by the fuselage has not been a focal point of previous noise prediction studies. A new approach is presented which uses PSU-WOPWOP to calculate the rotor noise coupled with NASA's Fast Scattering Code (FSC) to calculate the scattered noise field. The FSC uses the acoustic pressure and pressure gradient, supplied by PSU-WOPWOP at a specific frequency, to predict the manner in which helicopter bodies scatter noise. Representative BO-105 and heavy-lift quad tiltrotor cases are studied. The frequencies in each case was chosen such that the wavelength of the incident noise was comparable to the characteristic size of the scattering body. Significant tail rotor scattering was observed on an observer plane below the configuration, but the scattering of main rotor noise was negligible. Significant scattering was found on a plane beneath the configuration when the quad tiltrotor body was in the plane of the rotors. When the rotors were elevated so that the in-plane noise did not impinge upon the fuselage, little scattering was observed. All cases demonstrate the potential importance of acoustic scattering by the airframe components.

Original languageEnglish (US)
Pages (from-to)2242-2257
Number of pages16
JournalAnnual Forum Proceedings - AHS International
Volume3
StatePublished - Aug 28 2008
Event64th Annual Forum - AHS International - Montreal, Canada
Duration: Apr 29 2008May 1 2008

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Acoustic noise
Acoustics
Scattering
Rotors
Fuselages
Helicopter rotors
Airframes
Pressure gradient
Helicopters
NASA
Wavelength

All Science Journal Classification (ASJC) codes

  • Engineering(all)

Cite this

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Acoustic scattering of rotorcraft noise. / Lee, Seongkyu; Erwin, James P.; Brentner, Kenneth Steven.

In: Annual Forum Proceedings - AHS International, Vol. 3, 28.08.2008, p. 2242-2257.

Research output: Contribution to journalConference article

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N2 - The scattering of helicopter rotor noise by the fuselage has not been a focal point of previous noise prediction studies. A new approach is presented which uses PSU-WOPWOP to calculate the rotor noise coupled with NASA's Fast Scattering Code (FSC) to calculate the scattered noise field. The FSC uses the acoustic pressure and pressure gradient, supplied by PSU-WOPWOP at a specific frequency, to predict the manner in which helicopter bodies scatter noise. Representative BO-105 and heavy-lift quad tiltrotor cases are studied. The frequencies in each case was chosen such that the wavelength of the incident noise was comparable to the characteristic size of the scattering body. Significant tail rotor scattering was observed on an observer plane below the configuration, but the scattering of main rotor noise was negligible. Significant scattering was found on a plane beneath the configuration when the quad tiltrotor body was in the plane of the rotors. When the rotors were elevated so that the in-plane noise did not impinge upon the fuselage, little scattering was observed. All cases demonstrate the potential importance of acoustic scattering by the airframe components.

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