Broadband sound insulation of an open duct with side-branch resonators in airflow environment

• A theoretical model is developed for calculating the transmission loss of a side-branch resonator incorporating impedance correction with background airflow. • The sound insulation performance of single resonator and dual resonators are theoretically, numerically and experimentally analyzed in different background airflow. • Broadband sound insulation performance of an open duct with side-branch resonator array in airflow environment is systematically investigated. • The average transmission loss is greater than 40 dB in 0.1 ma background airflow environment. Sound insulation in airflow environment has significant implications in many fields like chemical pipes, gas-wave refrigerator, and car silencers, etc. In this paper, the broadband sound insulation performance of an open duct with side-branch resonator array with inserted neck tubes in airflow environment is systematically investigated. A theoretical model is first developed for calculating the transmission loss of a side-branch Helmholtz resonator with inserted neck tube incorporating impedance correction due to background airflow. The sound insulation performance of the single resonator and dual resonators with inserted neck tubes are theoretically, numerically and experimentally analyzed in zero background airflow, 0.05 ma and 0.1 ma background airflow. The dual side-branch resonator system exhibits coupled acoustic characteristics that allows the linear superposition of sound insulation effects. Theoretical analysis, finite element numerical simulations, and experimental measurements demonstrate that an open duct with multiple side-branch resonators can achieve a broadband sound insulation band in the frequency range of 1000–2200 Hz, with average transmission loss greater than 40 dB even in 0.1 ma background airflow environment. This research presents a practical approach for designing broadband sound absorbers under airflow environment