| Summary: | 碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 103 === This study aims to investigate the noise emitted by the machine’s inlet and outlet ports, with the quarter-wave resonator and the Herschel-Quincke tube applied for noise suppression. Finite element simulation is conducted for the cavity and the duct for sound transmission loss analysis. The ways to achieve broadband silencing effect are examined for a specified noise frequency. By increasing the cross-sectional area due to the increase in the number of silencers used, performance of both the quarter-wave resonator and the Herschel-Quincke tube is improved. The quarter-wave resonator is superior to the Helmholtz resonator in that the former only requires the tube length to be specified, whereas the latter requires the design of the cavity volume which is affected by the neck area chosen. The quarter-wave resonator is applied in the experiment for noise suppression of a portable vacuum cleaner. The silencer is created using the 3D printing technology. Because it is difficult to print a large model using 3D printing, the shape of the resonator is revised accordingly, which results in slight deviation of the originally designed main frequency. However, the performance is not severely affected due to the broadband design. Experimental study includes the traditional sound pressure measurement, three- microphones, and four-microphone measurements. Based on the observation of both the experiment and computer simulation, it is demonstrated that Herschel-Quincke tube is more effective than the quarter-wave resonator in terms of effective band width and actual implementation. Noise suppression of a hand dryer is thus conducted using the Herschel-Quincke tube.
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