Acoustics of a Mixed Porosity Felt Airfoil

Abstract

Lifting surfaces produce noise in operation, and porous materials have been shown to reduce this noise. Acoustic measurements were made on three arrangements of poroelastic material: full-chord porosity, full-chord impermeability, and mixed porosity. A scaling scheme is presented that collapses the spectra acquired at different Reynolds numbers. The results are compared to applicable published data. The noise reduction produced by the mixed porosity arrangement is found to be similar to the fully-porous arrangement at low Reynolds numbers. The noise reduction produced by the mixed and fully-porous foils does not match over the entire frequency range at higher Reynolds numbers.

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Document Details

Document Type
Technical Report
Publication Date
Jun 06, 2016
Accession Number
AD1018105

Entities

People

  • Aren Hellum

Organizations

  • Naval Undersea Warfare Center

Tags

Communities of Interest

  • Energy and Power Technologies
  • Weapons Technologies

DTIC Thesaurus Topics

  • Acoustic Impedance
  • Acoustics
  • Boundary Layer
  • Frequency
  • Lifting Surfaces
  • Materials
  • Measurement
  • Noise
  • Noise Reduction
  • Porosity
  • Porous Materials
  • Reynolds Number
  • Spectra
  • Surfaces
  • Three Dimensional
  • Trailing Edges
  • Undersea Warfare

Fields of Study

  • Physics

Readers

  • Acoustics.
  • Aerodynamics.
  • Surface Engineering/Surface Coating Technology.