AEROACOUSTIC PERFORMANCE OF COMPACT META-LINER FOR BROADBAND SOUND ABSORPTION

Design for highly effective acoustic meta-liners with broadband sound attenuation under grazing flow is a challenging topic because their working performance with flow practically is usually discrepant from many theoretical models, and difficult to predict accurately. In this paper, a compact meta-liner is proposed with broadband sound absorption under grazing flow. It comprises a series of designed absorbers with C-shaped enclosures (CSEs) and embedded microperforated panels (MPPs). The theoretical and numerical models are first introduced to evaluate the sound absorption performance of a single and parallel configurations of the designed absorbers. After that, the aeroacoustic performance of the proposed meta-liner under grazing flow is studied using finite element method (FEM) and validated by experiments. By utilizing the acoustic impedance model of the MPP that incorporates flow effects, the transmission loss (TL) of the meta-liner can be accurately predicted and controlled to maintain high broadband levels at flow speeds ranging from 0 to 30 m/s. There is a good agreement between prediction result and experimental data. With proper design of the perforation property of MPP, the absorption peaks and troughs can be maintained or even enhanced with the flow effect. Our results provide new insights into the design of metamaterials for aero-noise control engineering and the development of meta-liners for airflow applications.