The effect of flow on semi active control of duct noise with a Helmholtz resonator

摘要

Side-branch Helmholtz resonators are widely used in duct tonal noise control and the developing semi active control enables the classical control method works effectively under changing environments. The duct system is always accompanied with flow for air exchange or heat transfer. However, the flow has a significant impact on the sound absorption performance of the resonator. The main purpose of this paper is to investigate the effect of flow on the semi active Helmholtz resonator for duct noise control. The discontinuity condition at the joint due to a low Mach number flow is analytically formulated according to the conservation of the momentum and mass of air flow. The discontinuity function is used for deriving the controller transfer function. The proposed transfer function optimally tunes the termination impedance of Helmholtz resonator to reach a broadband noise control.