While most of the conventional acoustic liner which comprised of a micro-perforated panel (MPP) backed by a honeycomb structure shows good acoustic performance at high or medium frequency range, there is still very challenging for them at low-frequency range. Difference from MPP where resonance frequency of a MPP based liner is much depended on the backing space and shifting the absorption peak of the liner to low-frequency range generally makes the structure bulky and down-grades the absorbing quality, Helmholtz resonators shows easy frequency-tuning ability and outstanding absorption at low-frequency. In this research, by carefully design, the proposed designs of acoustic liner based on multiple Helmholtz resonators (MHR) show very good absorption in a broadband at low-frequency. First, a super unit-cell which is an annulus disk comprised of three segments or Helmholtz resonators is numerically studied to tune the working frequency band into the desired region, to form a broadband working region and to have the supercells absorbing potential. Afterward, the proposed liner constructed by patterning the supercells along the central axis of the liner is studied on absorption by using both commercial code (COMSOL) and theoretical analysis. The results show high absorption (>80%) at low-frequency broadband (400Hz to 650Hz) and good agreement between numerical and theoretical analysis. The proposed design and analysis can be served as effective model and tool for design and constructing advanced acoustic liners.

Date Published: 1 April 2019
PDF
Proc. SPIE 10972, Health Monitoring of Structural and Biological Systems XIII, 1097218 (1 April 2019); doi: 10.1117/12.2514364

Published in SPIE Proceedings Vol. 10972:
Health Monitoring of Structural and Biological Systems XIII
Paul Fromme; Zhongqing Su, Editor(s)