An Expansion Scheme for the Noise from Circular Jets

Abstract : An expansion scheme for the noise from circular jets is derived which takes account of the geometrical configuration of circular jets and of recent observations of jet turbulence. It is found that only a relatively small number of turbulence components, characterized by their frequency and azimuthal wave-number, contribute essentially to the far-field noise. A jet thickness parameter and a convection parameter strongly influence the sound radiation. Most of the phenomena of jet noise known from experiments can be explained by this very general solution. Theoretical results derived previously by means of the 'eddy model' of turbulence are also contained in the present solution. These results are special, since they were obtained under very restricting assumptions. (Author)