Localization of aeroacoustic sources by using time-reversal and beamforming techniques

The study deals with the localization of aeroacoustic sources in flows by using array processing techniques. In such situations, the source is located in the flow and the propagation model must properly take into account flow effects, with possible temperature gradients. The resolution of the inverse problem can rely: (i) either on the numerical simulation of the propagation by using the time-reversal principle; (ii) or on using the beamforming technique, provided a high-frequency model of the Green function is used, such as that given by a simplified analytical model or by ray-tracing. The advantages and links between the two approaches are discussed. Some comparisons in terms of localization error are then provided, based on simulated data, both in the time and frequency domains. The case of a pulse in a shear flow is considered, showing similar performances for both methods. Then a harmonic source in a shear flow and in a jet flow is studied, with possible temperature gradients, showing the limitations...