Analytical Study of the Noise Generated by a Coanda Wall Jet Circulation Control Device

Abstract

An analysis is made of the production of sound by a hydrofoil with a Coanda wall jet circulation control (CC-) device. Three principal sources of the radiation are identified: very low frequency "curvature noise" generated by the interaction of boundary layer turbulence with the rounded trailing edge of the hydrofoil; higher frequency sound produced at the Coanda jet slot. The latter includes "passive slot noise" caused by the scattering of turbulence near field pressures generated by the exterior boundary layer at the slot lip. The acoustic spectrum is greatly extended to much higher frequencies if the Coanda jet is turbulent; the sound produced by the interaction of this turbulence with the lip tends to dominate the spectrum at frequencies (f) (Hz) greater than about U(j)/h where is the slot width and U(j) the Coanda jet speed. Sample numerical results are presented for a typical underwater application that indicate that at this and higher frequencies the slot noise can be 20 dB or more greater than conventional trailing edge noise.

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Document Details

Document Type
Technical Report
Publication Date
Oct 01, 2000
Accession Number
ADA383801

Entities

People

  • Michael S. Howe

Organizations

  • Boston University

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Boundaries
  • Boundary Layer
  • Boundary Layer Flow
  • Curvature
  • Diffraction
  • Far Field
  • Fluid Dynamics
  • Frequency
  • Geometry
  • Layers
  • Mach Number
  • Near Field
  • Radiation
  • Scattering
  • Trailing Edges
  • Turbulent Mixing
  • Very Low Frequency

Fields of Study

  • Physics

Readers

  • Acoustics.
  • Fluid Dynamics.