Two-dimensional acoustic analysis of a flute-like silencer

The passive control of low-frequency duct noise remains a technical challenge. Herschel- Quincke (H-Q) tube is effective in low frequency noise reflection. However, it relies heavily on the length difference between the main duct and the bypass. Previous studies showed that, in a H-Q tube, when the bypass is filled with a light gas and covered by tensioned membranes, the H-Q tube becomes a flute-like silencer [L.Huang, Attenuation of low frequency duct noise by a flute-like silencer, Journal of Sound and Vibration 326 (2009) 161-176]. Another resonance occurs and the transmission loss spectrum can keep a desirable high level. In this paper, a two-dimensional analytical model for flute-like silencer is developed for more parametric studies. It is shown that the two-dimensional model has superiority in accuracy, especially for the case with long membranes or deep cavity. The details of the modal behavior of this coupled membrane-bypass system is also analyzed and a parametric study is conducted to obtain optimal design.