The Improvement on Noise Attenuation Performance of a Duct-resonator System

Abstract

The Helmholtz resonator (hereafter resonator) is qualified as a silencer with a narrow noise attenuation band at its designed resonance frequency. Combining several resonators in line is a possible way to produce a broader noise attenuation band. This paper focuses on improving the noise attenuation performance of a duct-resonator system at low frequency. Two types of periodic duct-resonator system are analyzed theoretically and numerically: a duct-resonator system with identical resonators and a modified duct-resonator system with periodic two-resonator arrays. The planar wave theory and the transfer matrix method are used to investigate wave propagation in the duct-resonator system. The theoretical prediction results yield satisfactory agreement with the Finite Element Method simulation results. The results indicate that both the periodic duct-resonator system and the modified duct-resonator system can broaden the noise attenuation band. Furthermore, the proposed modified duct-resonator system in this paper contributes to a relatively broader noise attenuation band than the periodic duct-resonator system. The modified duct-resonator system provides a useful method for the design of such a system, in order to obtain a relatively broadband noise attenuation.