Reduction of low-frequency tonal noise from rotating sources using non-planar acoustic metasurfaces

Le résumé fourni par la source

We propose a non-planar acoustic metasurface designed to mitigate tonal noise generated by rotating sound sources within a short duct. The surface impedances along the inner wall of the duct are optimally tuned to complex values that minimize acoustic energy emanating through openings of the duct based on the theoretical model of effective impedances of metasurfaces composed of sub-wavelength Helmholtz resonators. Numerical results demonstrate that tonal noise is effectively controlled in the near field, and its propagation into the far field is significantly reduced. The proposed design method, originally developed for a single target frequency, is further extended to address multiple harmonic frequencies generated by rotating sources, suggesting its potential applicability to multi-frequency noise control in ducted fans or rotors.

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