On the variations of acoustic absorption peak with particle velocity in Micro-Perforated Panels at high level of excitation
Résumé
The acoustic behavior of micro-perforated panels (MPP) is studied theoretically and experimentally at highlevel of pressure excitation. A model based on Forchheimer’s regime of flow velocity in the perforations isproposed. This model is valid at relatively high Reynolds numbers and low Mach numbers. The experimentalmethod consists in measuring the acoustical pressure at three different positions in an impedance tube, thetwo measurement positions usually considered in an impedance tube and one measurement in the vicinityof the rear surface of the MPP. The impedance tube is equipped with a pressure driver instead of the usualloudspeaker and capable of delivering a high sound pressure level up to 160 dB. MPP specimens made outof steel, dural and polypropylene were tested. Measurements using random noise or sinusoidal excitationin a frequency range between 200 and 1600 Hz were carried out on MPPs backed by air cavities. It wasobserved that the maximum of absorption can be a positive or a negative function of the flow velocity in theperforations. This suggests the existence of a maximum of absorption as a function of flow velocity. Thisbehavior was predicted by the model and confirmed experimentally.
Domaines
Acoustique [physics.class-ph]Origine | Fichiers produits par l'(les) auteur(s) |
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