Noise Analysis of B.I. Centrifugal Fan

• Main Authors: Hung Chung-Yang, 洪宗揚
• Other Authors: Lin Sheam-Chyun
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/56940760966429957442

碩士 === 國立臺灣科技大學 === 機械工程研究所 === 84 === An investigation of the performance and noise for a backward- inclined（B.I.）centrifugal fan is executed. At first, with the aids of AMCA test chamber and sound level meter, a set of relations correlating the performance and noise of fan is obtained. Next, a parametric study on the geometry of fan is carried out to enhance the understanding of the corresponding influences caused by those variations. The parameters considered here include the width and inlet diameter of impeller, radius and axial clearances between inlet cone and impeller, and the attachment of center body. Moreover, several noise attenuation methods, such as quarter-wavelength resonator and modification on cut-off proposed, are applied to improve the fan''s noise problem. From experiments, resonator demonstrates an significant noise-reduction effect while the slight improvements are observed for the other methods. At the first harmonic frequency 267 Hz, the noise level can be reduced by 16 dBA for low volume-flow- rate. In addition, the reductions at second and third harmonic frequencies are 20 dBA and 7 dBA, respectively. Furthermore, the sound intensity measurement is utilized to identify the characteristics of the sound fields for all the cases discussed.