Abstract
Transmission loss characteristics of silencers composed of multiple side-branch tubes have been investigated to control noise in ventilation systems. Numerical results show that the multi-effect of a few identical-sized tube units can regain resonance performances in the narrow frequency range which are lowered by flow. It is also shown that the multi-effect of different-sized units of several kinds can widen effective ranges of frequency for reducing components of random noise traveling in an incompressible flow. Moreover the above results are verified by experiments.
