| Summary: | 碩士 === 國立臺灣大學 === 工程科學及海洋工程學研究所 === 102 === This study is to concentrate on the influence of structure parameters on the acoustic attenuation when the sound passes through perforated muffler. This study is to use acoustic simulation package as basis and the chamber of silencer as parameter to design some resonant muffler with variable-chamber, and make acoustic simulation on a perforated duct in an uncoupled steady fluid flow.
In actual duct silencer or muffler design, the design is adopt a lot of holes to reduce the internal resistance of the fluid or increase attenuating effect. Due to the existence of holes, it resulting in difficulties in modeling finite element mesh. This study uses the concept of transfer admittance, which indirectly simulates these small holes such that being neglected while modeling. Therefore, in order to simulate those holes of perforated plate, the relationship of transfer admittances among the side edges of perforated plate grid must be defined when making acoustic calculation in progress.
This study makes simulation and experiment for various chamber. The result of study shows that when the volume of chamber of muffler becomes greater, its main effectiveness will exist at lower frequency. Meanwhile, this study also found that, while two chambers of different types are used in the silencer, the performance of silencer have synergistic effects. That means one chamber eliminates a single frequency noise, but dual chambers can eliminate noises at different frequency.
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