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Considering an open jet wind tunnel set-up, the effect of the turbulent shear layer on the acoustic propagation is a first order problematic to perform accurate acoustic source localization with microphone arrays. Notably, the travel times between sources within the flow and sensors in the out-of-flow region is modified by the turbulence structures, thus inducing a significant coherence loss between the microphones. In this paper, the coherence loss issue is evidenced experimentally with a omnidirectional source flush mounted in a profile and measured with a mems planar array at different Mach numbers. Additionally, array measurements synchronized with Particle Image Velocity (PIV) samples of the turbulent shear layer are operated to evaluate the direct correlation between coherence loss and turbulence features in the shear layer. Based on these results and the insights provided by the PIV, processing approaches of the microphone signals are discussed to make up with the time delays responsible for the coherence loss.
Chambon et al. (Thu,) studied this question.