Broadband low-frequency noise attenuation performance of a Helmholtz Resonator Array (HRA) in the presence of grazing flow

Abstract

The sound-absorbing metamaterial (SAMM), known for its lightweight and compact nature, has become a promising solution for low-frequency noise control in the ventilation ductwork systems. However, the current SAMM design strategies often neglect the consideration of noise attenuation in the presence of grazing flow. This study aims to present a SAMM composed of the Helmholtz Resonator Array (HRA) that exhibits broadband low-frequency transmission loss performance under low-speed flow conditions. Additionally, a theoretical model is developed by integrating Guess’s semi-empirical model with a flow correction term to predict the transmission loss performance of the designed HRA under various grazing flow velocities. The designed HRA is composed of 8 single Helmholtz resonators and is optimized to increase the noise attenuation band. Results show that the transmission loss of the designed HRA can achieve around 20 dB/m in the prescribed frequency range of 200 to 800 Hz under grazing flow speeds of 0–20 m/s, and the proposed theoretical model can be used to predict transmission loss performance under different grazing flow speeds. The design strategy of the HRA offers an effective solution for noise control in heating, ventilation and air conditioning (HVAC) duct systems.