Time frequency analysis of sound from a maneuvering rotorcraft

James H. Stephenson, Charles E. Tinney, Eric Greenwood, Michael E. Watts

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The acoustic signatures produced by a full-scale, Bell 430 helicopter during steady-level-flight and transient roll-right maneuvers are analyzed by way of time-frequency analysis. The roll-right maneuvers comprise both a medium and a fast roll rate. Data are acquired using a single ground based microphone that are analyzed by way of the Morlet wavelet transform to extract the spectral properties and sound pressure levels as functions of time. The findings show that during maneuvering operations of the helicopter, both the overall sound pressure level and the blade-vortex interaction sound pressure level are greatest when the roll rate of the vehicle is at its maximum. The reduced inflow in the region of the rotor disk where blade-vortex interaction noise originates is determined to be the cause of the increase in noise. A local decrease in inflow reduces the miss distance of the tip vortex and thereby increases the BVI noise signature. Blade loading and advance ratios are also investigated as possible mechanisms for increased sound production, but are shown to be fairly constant throughout the maneuvers.

Original languageEnglish (US)
Pages (from-to)5324-5339
Number of pages16
JournalJournal of Sound and Vibration
Volume333
Issue number21
DOIs
StatePublished - Jan 1 2014

Fingerprint

rotary wing aircraft
maneuvers
blade-vortex interaction
sound pressure
Acoustic waves
Vortex flow
acoustics
helicopters
Helicopters
turbine wheels
miss distance
signatures
Microphones
blades
microphones
bells
wavelet analysis
Wavelet transforms
Turbomachine blades
vehicles

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Stephenson, James H. ; Tinney, Charles E. ; Greenwood, Eric ; Watts, Michael E. / Time frequency analysis of sound from a maneuvering rotorcraft. In: Journal of Sound and Vibration. 2014 ; Vol. 333, No. 21. pp. 5324-5339.
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Time frequency analysis of sound from a maneuvering rotorcraft. / Stephenson, James H.; Tinney, Charles E.; Greenwood, Eric; Watts, Michael E.

In: Journal of Sound and Vibration, Vol. 333, No. 21, 01.01.2014, p. 5324-5339.

Research output: Contribution to journalArticle

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