The radiation of sound by the instability waves of a compressible plane turbulent shear layer

Christopher K.W. Tam, Philip J. Morris

Research output: Contribution to journalArticle

193 Scopus citations

Abstract

The problem of acoustic radiation generated by instability waves of a compressible plane turbulent shear layer is solved. The solution provided is valid up to the acoustic far-field region. It represents a significant improvement over the solution obtained by classical hydrodynamic-stability theory which is essentially a local solution with the acoustic radiation suppressed. The basic instability-wave solution which is valid in the shear layer and the near-field region is constructed in terms of an asymptotic expansion using the method of multiple scales. This solution accounts for the effects of the slightly divergent mean flow. It is shown that the multiple-scales asymptotic expansion is not uniformly valid far from the shear layer. Continuation of this solution into the entire upper half-plane is described. The extended solution enables the near-and far-field pressure fluctuations associated with the instability wave to be determined. Numerical results show that the directivity pattern of acoustic radiation into the stationary medium peaks at 20 degrees to the axis of the shear layer in the downstream direction for supersonic flows. This agrees qualitatively with the observed noise-directivity patterns of supersonic jets.

Original languageEnglish (US)
Pages (from-to)349-381
Number of pages33
JournalJournal of Fluid Mechanics
Volume98
Issue number2
DOIs
StatePublished - May 1980

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Fingerprint Dive into the research topics of 'The radiation of sound by the instability waves of a compressible plane turbulent shear layer'. Together they form a unique fingerprint.

  • Cite this