背後空気層を有する孔あき板の吸音性能と流れ場との関係

抄録

The present paper focuses on the effect of flow velocity on acoustic absorption performance of perforated plate. A perforated plate has singe orifice at the center of plate. We experimentally measured the flow velocity, acoustic pressure, and transfer function using the improved acoustic impedance tube. The normal incidence absorption coefficient was calculated from the measured transfer function using transfer function methods. As the flow velocity of air passing through the orifice increased, the peak level of the acoustic absorption coefficient decreased. Velocity measurements were performed around perforated plate by means of particle image velocimetry. The pair vortices were formed clearly at the downstream of the orifice due to incident sound of pure tone.