A modified sonic black hole structure for improving and broadening sound absorption

In order to improve and broaden the absorption performance of Sonic Black Hole (SBH), we propose a modified SBH structure with micro-perforated panels which is embedded the multiple resonator cavities, and investigate the sound absorption effect of the structure. Characteristics of acoustic streaming effects are embodied in sound pressure and flow velocity distribution. Further, proposed SBH structure can achieve high sound absorption under 6.0 kHz. Based on the symmetry of the structure, the Two-dimensional axisymmetric Finite Element Method (FEM) model is proposed to study the sound absorp-tion mechanism, which shows that the change of flow velocity gradient of acoustic medium leads to the loss of acoustic energy inside the structure. By discussion on acoustic streaming effects of different fre-quencies, the resonator cavity and micro-perforated panels contributes more to the sound absorption performance at low frequencies, and SBH produces a sound absorption advantage at high frequencies. The theoretical calculation and simulation result match and prove the correctness of the sound stream-ing effect. Sound absorption tests by acoustic impedance tube confirm that the proposed structure can maintain a sound absorption coefficient of over 0.5 in the range of 0.05-6.0 kHz. The combination of micro-perforated panels and SBH structure is widely applicable to muffler design and has good applica-tion prospects. & COPY; 2023 Elsevier Ltd. All rights reserved.

Automated summary

This paper proposes a modified Sonic Black Hole (SBH) structure with micro-perforated panels embedded with multiple resonator cavities to enhance the absorption performance. The structure achieves high sound absorption under 6.0 kHz. The resonator cavity and micro-perforated panels contribute more to the sound absorption at low frequencies, while the SBH has an advantage at high frequencies. Sound absorption tests confirm that the proposed structure maintains a sound absorption coefficient of over 0.5 in the range of 0.05-6.0 kHz. The combination of micro-perforated panels and SBH structure has wide applications in muffler design.