Noise Prediction for a Turbulent Jet Using an LES/CAA Method

Abstract

Acoustic simulations of a Mach number 0.9, Reynolds number 3,600 and a Mach number 0.9, Reynolds number 400,000 round jet are performed based on a two-step approach using a large eddy simulation (LES) for the flow field and a solution of the acoustic perturbation equations (APE) for the acoustical field. The present simulations are compared with available experimental and numerical results at similar flow conditions. Both jet simulations are in good agreement with the noise characteristics of jets at such varying Reynolds numbers showing the jet noise physics to be successfully captured in the present simulations. The dominant source term in the APE system for jet noise is shown to be the Lamb vector. The maximum amplitudes of the sound pressure levels for the high Reynolds number jet are overpredicted compared with the direct LES approach. 1 A comparison with data from the literature shows the APE method to be less susceptible to the extent of the source region than the Lighthill volume method.