On Two Mechanisms of Sound Generation in Turbulent Jets

Abstract

Features of the processes of sound generation in turbulent jet flows are analyzed. Two possible processes are considered, namely, noise of dissipating turbulence and noise generated by largescale turbulent-flow perturbations which accompany propagation of turbulent jets. The data of the theoretical and experimental investigations of statistical turbulence theory are used to estimate the first of the above-mentioned effects. The data of computational experiments are used to analyze the process of sound generation by large-scale perturbations. In these numerical experiments time-dependent subsonic turbulent jet flows were directly calculated using the LES technology and the experimental data. It is shown that the noise of large-scale perturbations can be satisfactorily reproduced by the numerical simulation and its properties correspond to the experiments on studying sound generation in jets; the contribution of noise of dissipating turbulence to the total jet noise seems to be insignificant.