Aeroacoustic Source Identification with Effects of Solid Boundaries Using a Numerical Time-reversal Technique
Résumé
Interactions between flows and objects produce noise. Finding the locations and identifying source features are still a challenge in experimental aeroacoustics. For instance, traditional methods such as the beamforming technique may not give satisfactory results in presence of solid boundaries in flows, resulting from the object under study or from the experimental facility. The aim of this work is to propose an alternative strategy based on the aeroacoustic time-reversal method for the localization of sources of flow-induced noise, accounting for the solid boundaries of objects. First, a direct simulation is done to compute the radiated pressure for different sources in configurations involving solid boundaries. The base flow is supposed to be stationary and is computed with a Reynolds-averaged Navier?Stokes solver while the pressure field is computed by solving the linearized Euler equations with a in house solver working with unstructured meshes. In a second step, the signals recorded on virtual microphones located on the boundaries of the domain are reversed and re-emitted in a medium where the base flow has also been reversed. Both 2D and 3D configurations are investigated. First, the whole method is validated on academic configurations. Then, localization of a synthetic dipole noise source near the trailing edge of a NACA 0012 airfoil in flow is done with a precision at wavelength. First results coupling experimental data with the numerical localization stage will also be presented and discussed. This study shows that the aeroacoustics time reversal method processing strategy is promising for aeroacoustics investigations in wind-tunnels, and is a first attempt toward a hybrid experimental/numerical approach.
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