Design of an impedance matching acoustic bend

TL;DR

This paper introduces an impedance matching acoustic bend design using sub-wavelength unit cells with tunable properties to enhance sound transmission and bending efficiency.

Contribution

It presents a novel acoustic bend structure that simultaneously tunes mass density and bulk modulus for improved impedance matching and transmission.

Findings

Enhanced sound transmission compared to non-matched bends

Effective control of refraction index and impedance

High bending efficiency demonstrated in simulations

Abstract

We propose the design of an impedance matching acoustic bend in this article. The bending structure is composed of sub-wavelength unit cells with perforated plates and side pipes, whose mass density and bulk modulus can be tuned simultaneously. So the refraction index and the impedance of the acoustic bend can be modulated simultaneously to guarantee both the bending effect and the high transmission. The simulation results of sound pressure field distribution show that the bending effect of the impedance matching acoustic bend is very good. Transmission spectra of the impedance matching acoustic bend and the acoustic bend composed of perforated plates only are both calculated for comparison. The results indicate that the impedance matching acoustic bend is successful in improving the impedance ratio and increasing the transmission obviously.