Phased acoustic arrays have been used successfully to locate propulsive and nonpropulsive aeroacoustic sources with the array located both in a moving wind-tunnel stream and in still air. Multiple or distributed sources may vary over the full range in coherence level, particularly when local reflections are present. A constant contour level integration boundary is defined and assessed for accuracy. The effect of varying coherence between two simple sources is simulated and analyzed with respect to both peak and integrated levels. The effects of variable coherence of background noise on different array signal processing approaches are also discussed. Simple beamformed cross-spectral and coherence parameters are defined for use in analysis of experimental phased array data.
W. Clifton Horne, Stephen M. Jaeger, Julie Hayes, and Srba Jovic, “Effects of Distributed Source Coherence on the Response of Phased Acoustic Arrays,” AIAA 2000-1935, 6th AIAA/CEAS Aeroacoustics Conference, Lahaina, HI, June 12-14, 2000.