STUDY ON ACOUSTIC ATTENUATION PERFORMANCE OF PERFORATED BRANCH TUBE SILENCER ATTACHED WITH THIN FIBER LAYER

摘要

The side-branched tube is widely used in noise control engineering, and increasing the number of tubes can improve the performance of sound absorption. In this paper, the transmission loss calculation model is built for multi-side-branched tube by using transfer matrix method. The calculation results show that, with the increasing of the number of side-branched tube the sound absorption performance is getting better, but the pass-by frequency on which the transmission loss is 0dB appears. For solving the problem of pass-by frequency, the perforated panel is added between the side and main tubes. In order to enhance the resistance effect, the thin fiber layer is attached on the perforated panel. Using the theoretical model, the transmission loss of side-branch tube with perforated panel and thin fiber layer is calculated. The results show that the peak value of transmission loss curve decreases, but the value on the pass-by frequency increases and the curve is getting smooth. The study shows that the problem of pass-by frequency is solved by perforated panel attached with thin fiber layer.