The energy absorption of Helmholtz resonators enhanced by Acoustic Black Holes

Helmholtz Resonators (HR) typically exhibit narrow band absorption with a center frequency determined by the characteristic resonance of the cavity. Although several approaches have been proposed in the past in order to improve the performance of HR systems, their operating bandwidth is still one of the main limiting factor. This study addresses a novel design that combines traditional HR with the concept of an Acoustic Black Hole. The HR cavity is partitioned by a flexible membrane having an embedded black hole. A fluid-structure interaction model was developed in order to simulate the coupled response of the system. Theoretical and numerical simulations show that the novel design not only broadens the operating frequency range but can substantially increase the energy absorption.