The generation of sound by aerodynamic sources in an inhomogeneous steady flow
1975; Cambridge University Press; Volume: 67; Issue: 3 Linguagem: Inglês
10.1017/s0022112075000493
ISSN1469-7645
Autores Tópico(s)Wind and Air Flow Studies
ResumoThis paper examines the effect of steady flow on the generation of sound by aerodynamic sources located in the neighbourhood of a scattering body. The analysis is facilitated by the use of a reverse-flow reciprocal theorem which is valid for a certain class of inhomogeneous flow problems. In the case of acoustic ‘bremsstrahlung’, in which sound is generated during the passage of a silent fluid inhomogeneity, such as an entropy spot, past an obstacle in the flow, an elegant discussion of the interaction can be given in terms of a renormalized Green's function. Here the effect of the obstacle is equivalent to a local distortion of the geometry of the three-dimensional space occupied by the medium, the extent of which governs the properties of the acoustic radiation. This is illustrated by means of a detailed analysis of the sound generated during the unsteady convection of a source of constant strength through a neck in a duct.
Referência(s)