Acoustic analogy approaches can be used to express the sound radiation from a turbulent flow as the convolution product of a propagator and a source term. This paper presents an acoustic analogy-based analysis that properly accounts for circumferential variations of the propagator across the source-correlation region in an axisymmetric jet. The analysis shows that including azimuthal source non-compactness effects leads naturally to a formula for the acoustic spectrum in which each circumferential propagator mode couples only to its corresponding Fourier component of the source term. This significantly affects the radiated sound field, since the lower-order propagator modes radiate much more efficiently than the higher-order modes, while the spectra of the lower-order source modes tend to be quite different from those of the energy-containing modes. The result depends on the Reynolds stress autocovariance tensor, which must be accurately modeled in order to obtain realistic predictions of the sound field. A relatively simple, experimentally based, model of this tensor is proposed and combined with Reynolds-Averaged Navier-Stokes solutions to obtain predictions of the noise from a moderately supersonic cold round jet. The results are then compared with experimental data.
展开▼
