On wavenumber spectra for sound within subsonic jets

Argawal, A., Sinayako, S. and Sandberg, R.D. (2014) On wavenumber spectra for sound within subsonic jets. Journal of the Acoustical Society of America, 136 (3), 1029-1035. (doi:10.1121/1.4890648).

Record type: Article

Abstract

This paper explores the nature of sound spectra within subsonic jets. Three problems of increasing complexity are presented. First, a point source is placed in a two-dimensional plug flow and the sound field is obtained analytically. Second, a point source is embedded in a diverging axisymmetric jet and the sound field is obtained by solving the linearized Euler equations. Finally, an analysis of the acoustic waves propagating through a turbulent jet obtained by direct numerical simulation is presented. In each problem, the pressure or density field is analyzed in the frequency-wavenumber domain. It is found that acoustic waves can be classified into three main frequency-dependent groups. A physical justification is provided for this classification. The main conclusion is that, at low Strouhal numbers, acoustic waves satisfy the d'Alembertian dispersion relation.

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