Acoustic Efficiency of Boundary-Layer Transition.

Abstract

The radiated noise due to incompressible boundary-layer transition on an infinite, rigid planar surface has been recently analyzed (ARL TM 78-204, 28 July 1978). The results of that analysis are the power spectrum and directivity of the farfield sound pressure due to a unit span of transition zone flow. In this note, we further analyze transition zone flow noise by deriving an expression for the acoustic efficiency. We compare this efficiency with the acoustic efficiency of a fully-developed turbulent boundary layer and find that the radiation from the transition zone is considerably more efficient. In particular, for typical values of the Reynolds numbers upon which this comparison depends, transition zone radiation is approximately a thousand times more efficient. (Author)

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Document Details

Document Type
Technical Report
Publication Date
Nov 07, 1978
Accession Number
ADA062171

Entities

People

  • G. C. Launchle

Organizations

  • Pennsylvania State University

Tags

Communities of Interest

  • Energy and Power Technologies
  • Weapons Technologies

DTIC Thesaurus Topics

  • Boundary Layer
  • Boundary Layer Flow
  • Boundary Layer Transition
  • Flow
  • Jet Propulsion
  • Layers
  • Mach Number
  • Military Research
  • Navy
  • Noise
  • Power Spectra
  • Radiated Noise
  • Reynolds Number
  • Sound Pressure
  • Turbulence
  • Turbulent Boundary Layer
  • Universities

Fields of Study

  • Physics

Readers

  • Acoustics.
  • Computational Modeling and Simulation
  • Fluid Mechanics and Fluid Dynamics.