Wake model effects on the prediction of turbulence-interaction broadband noise in a realistic compressor stage

Abstract

The effects of the wake modelling on the prediction of the broadband noise generated by the impingement of the turbulent wakes on a stationary blade row are studied. The analysis focuses on the description of the wake shape that is usually approximated by a Gaussian curve for acoustical purposes. The prediction of the broadband noise is achieved using an analytical acoustic model dedicated to turbomachinery configurations. The characteristics of the model regarding the wake treatment are described. In order to provide a realistic reference for the wake shape, a low-speed axial compressor stage is analyzed using numerical RANS simulation. The unsteady flow-field structure is presented. The simulation is validated using a comparison with experimental data, with special attention paid for the wake numerical prediction. The shape of the rotor wakes is thoroughly described. The comparison between the simulated wake and the corresponding Gaussian approximation is detailed, showing differences between the two approaches. The broadband predictions yielded by the two wake models are finally compared. The use of the Gaussian approximation of the wakes shape for broadband noise prediction purposes is validated in the studied realistic configuration.