Acoustics performance of compact micro-perforated panel absorber with grazing flow

This paper presents numerical and experimental investigations into the acoustic behaviour of a micro-perforated panel (MPP) backed by a shallow cavity under a fully developed grazing flow. A three-dimensional time-domain computational fluid dynamics approach is applied alongside hybrid evaluation methods to accurately capture the acoustic behaviour variations of an MPP orifice. Meanwhile, a hybrid Rayleigh's end correction model for T-shaped resonators is utilized to calculate the acoustic reactance of a very shallow cavity and an acoustics impedance model of an orifice backing with shallow cavity at grazing flow is established. The proposed acoustic impedance model of orifice has been validated by experimental study. The practical significance of this study is that it elucidates the influence of cavities upon the acoustic behaviour of MPPs in the presence of grazing flows; furthermore, it proposes an impedance model that is more suitable for predicting the acoustic performance of booming compact meta-structures.