Experimental Evidence of Turbulent Source Coherence Affecting Jet Noise

Kurzfassung

This study is a follow-up to a theoretical and experimental investigation by Armstrong et al. aimed at directly coupling jet turbulence and noise. Since the numerical calculation of the far-field pressure from measured pressure correlations in the jet near field has not been achieved yet, both fields are analyzed separately and their respective space-time structures compared herein. Azimuthal coherence data of model jets and a jet engine reveal that the pressure field is always governed by a few low-order azimuthal constituents. This underlines the importance of "coherent structures" in the jet mixing zone.