The study of noise level dependence on flow parameters

The purpose of this paper is to study the effect of averaged characteristics of the turbulent flow in a pipe on the level of produced noise. The role of noise is played by hydrodynamic pressure fluctuations, increasing with rising Reynolds number, and the average flow velocity is considered as a flow parameter. As a result of the theoretical analysis of the correlation functions of the velocity and pressure fields, the dependence of the noise power on the average velocity was obtained. Numerical modeling of the turbulent flow was performed in a standard CFD package using Large Eddy Simulation (LES) approach. Flows of gas with a density of 100 kg/m3 in the range of Reynolds numbers from 3.2·10^4 to 1.3·10^5 were considered. The analysis of the temporal distribution of pressure and velocity fluctuations showed that they conform with the local isotropic turbulence model in the central part of the flow. The dependence of the noise level on the mean flow velocity was found by calculating the first and the second order moments for fluctuating hydrodynamic quantities. Comparison of the theoretical dependence with the results of numerical simulation showed good agreement.