The effects of crosswind flight on rotor harmonic noise radiation

Eric Greenwood, Ben W. Sim

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

In order to develop recommendations for procedures for helicopter source noise characterization, the effects of crosswinds on main rotor harmonic noise radiation are assessed using a model of the Bell 430 helicopter. Crosswinds are found to have a significant effect on Blade-Vortex Interaction (BVI) noise radiation when the helicopter is trimmed with the fuselage oriented along the inertial flight path. However, the magnitude of BVI noise remains unchanged when the pilot orients the fuselage along the aerodynamic velocity vector, "crabbing" for zero aerodynamic sideslip. The effects of wind gradients on BVI noise are also investigated and found to be smaller in the crosswind direction than in the headwind direction. The effects of crosswinds on lower harmonic noise sources at higher flight speeds are also assessed. In all cases, the directivity of radiated noise is somewhat changed by the crosswind. The model predictions agree well with flight test data for the Bell 430 helicopter captured under various wind conditions. The results of this investigation would suggest that flight paths for future acoustic flight testing are best aligned across the prevailing wind direction to minimize the effects of winds on noise measurements when wind cannot otherwise be avoided. Copyright

Original languageEnglish (US)
Title of host publication69th American Helicopter Society International Annual Forum 2013
Pages1414-1426
Number of pages13
StatePublished - Sep 9 2013
Event69th American Helicopter Society International Annual Forum 2013 -
Duration: May 21 2013May 23 2013

Publication series

NameAnnual Forum Proceedings - AHS International
Volume2
ISSN (Print)1552-2938

Other

Other69th American Helicopter Society International Annual Forum 2013
Period5/21/135/23/13

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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  • Cite this

    Greenwood, E., & Sim, B. W. (2013). The effects of crosswind flight on rotor harmonic noise radiation. In 69th American Helicopter Society International Annual Forum 2013 (pp. 1414-1426). (Annual Forum Proceedings - AHS International; Vol. 2).