Modeling aerodynamically generated sound of helicopter rotors

Kenneth S. Brentner, F. Farassat

Research output: Contribution to journalReview articlepeer-review

487 Scopus citations


A great deal of progress has been made in the modeling of aerodynamically generated sound of rotors over the past decade. Although the modeling effort has focused on helicopter main rotors, the theory is generally valid for a wide range of rotor configurations. The Ffowcs Williams-Hawkings (FW-H) equation has been the foundation for much of the development. The monopole and dipole source terms of the FW-H equation account for the thickness and loading noise, respectively. Blade-vortex-interaction noise and broadband noise are important types of loading noise, hence much research has been directed toward the accurate modeling of these noise mechanisms. Both subsonic and supersonic quadrupole noise formulations have been developed for the prediction of high-speed impulsive noise. In an effort to eliminate the need to compute the quadrupole contribution, the FW-H equation has also been utilized on permeable surfaces surrounding all physical noise sources. Comparisons of the Kirchhoff formulation for moving surfaces with the FW-H equation have shown that the Kirchhoff formulation for moving surfaces can give erroneous results for aeroacoustic problems. Finally, significant progress has been made incorporating the rotor noise models into full vehicle noise prediction tools. Published by Elsevier Science Ltd.

Original languageEnglish (US)
Pages (from-to)83-120
Number of pages38
JournalProgress in Aerospace Sciences
Issue number2-3
StatePublished - 2003

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Mechanics of Materials
  • Mechanical Engineering


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