設計環形消音器在軸流式扇葉噪音之改善

A Circular Silencer Design for Reduce the Noise of Axial Fan

吳建達 ； 白明憲

《中華民國振動與噪音工程學會論文集》 1999 (1999/05) Pp. 169-174

https://doi.org/10.30028/CSSVANNUAL.199905.0169

摘要

風扇噪音(fan noise)乃是噪音中一項重要來源，大部分對扇葉噪音改善的研究較偏向之氣體動力學之觀點，探討噪音形成之原因或由扇葉形狀著手，設計出較適合之角度或流線以符合低噪音之要求。一般而言扇葉噪音有兩個主要來源，一是扇葉與空氣作用產生之紊流聲場稱之氣流噪音(flow induce noise)，另一是扇葉末端與空氣相切形成之窄頻之週期性噪音(narrow band noise)。而此兩種音源主要都是發生在扇片之周圍及其末端。本研究則利用此一特性，在扇葉周圍設計一簡單的消音殼，經利用頻譜分析儀及噪音計量測，在扇葉通過頻率(Passing frequency)有15~20dB之聲壓噪音衰減量，而在其他頻率也有10dB左右的衰減量，證明此一設計雖然簡單但卻是一有效的噪音改善方法，此一設計觀念應該也可以應用在其他種類的扇葉。

並列摘要

Fan noise is one of the main sources of noise source. Most of the work on fan noise has been associated with aerodynamic, and many methods have been developed for its reduction. The noise generated by axial fan has two main components of noise. One is rotational blade passing noise with discrete or narrow band frequency components and the other turbulent noise with broadband frequency components. This paper describes a noise reduce device for axial fan which a circular silencer around the end of fan blades. The results of sound pressure level tests showing this design can reduce 15 to 20 dB in blade passing frequency and 10 dB in other broadband frequency. This concept can be applied in a practical fan design.