Sound absorption mechanism of sonic black hole with labyrinthine units and micro perforated panel

Acoustic black hole (ABH) is a technique capable of manipulating the propagation of flexural wave, and the sonic black hole (SBH) is a kind of ABH which is used to manipulate sound wave in a fluid medium. In this paper, we propose an SBH structure with labyrinthine units and combine with micro-perforated panel (MPP) to form a composite sound absorption structure. The sound absorption mechanism of the absorption structure is deeply investigated using numerical and simulation methods. The simulation reveals the sound absorption mechanism by acoustic streaming effects of composite sound absorption structure. We analyze the flow characteristics of the acoustic medium under acoustic excitation, and the effect of the flow field on the distribution of the acoustic field, and the energy dissipation distribution. Our theoretical results show that the sound absorption is attributed to the effects of sound energy focusing of ABH, the local resonance of MPP, and the acoustic energy localization and dissipation effect of labyrinthine units caused by large flow velocity gradients. Finally, the proposed composite sound absorption structure has good sound absorption performance, which is also confirmed by impedance tube experiments. It can provide a new way of thinking for the design and optimization of the SBH structure.

Automated summary

In this paper, a composite sound absorption structure with labyrinthine units and a micro-perforated panel (MPP) is proposed for the manipulation of sound waves in a fluid medium. The sound absorption mechanism is investigated using numerical and simulation methods, and it is found that acoustic streaming effects have a significant impact on the absorption mechanism. The sound absorption is attributed to sound energy focusing, local resonance, and acoustic energy localization and dissipation effects. The proposed structure exhibits good sound absorption performance and provides a new approach for the design and optimization of sonic black hole (SBH) structures.