Development of the Reference Sound Source for Calibrating Miniature Anechoic Rooms

• Main Authors: Chien-Feng Lee, 李建鋒
• Other Authors: Y.S. Chen
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/93361215974854550792

碩士 === 元智大學 === 機械工程學系 === 97 === In present day, noise is a common problem in our living surrounding. For finding the solvent, many of electronic and mechanical parts, like computer cooling fan, air compressor and so on, needed to proceeding noise test in anechoic or hemi-anechoic rooms before manufacture. But it would affect the result of the measurement of noise that depend on the rooms are correspond to standard or not. Thus, we need to use reference sound source to processing test, it could ensure all the products would not affect our life. However, it have standard of space for the rooms and it’s unrealistic for using a huge space to measure a tiny fan of computer. How to using the reference sound source in miniature anechoic rooms to simulate large-scale anechoic rooms is very practical. The reference sound source for large-scale anechoic rooms would cause more air flow in operation, and it not applies to miniature measurement environment. And the main major for this research is developing specific reference sound source for miniature anechoic rooms. The theory of reference sound source is using high-speed cross flow fan produce stable areoacoustic noise. And the design for fin would change noise and air flow of the fan, such as the angle of the fin when aero passes through and so on. This research is discussion on the effect of noise for changes fin’s design. The characteristics of fan including style of fan, ratio of impeller inner and outer diameter, gap between each fin and number of fin, and the sound pressure level also depend on all of these parameter. In this research, changing these parameter and proceed flow field noise numerical analyses for different angle by FLUENT. Here’s hoping to find out which angle can make the stable noise. Finally, design the cross flow fan that can produce less wind flow, and control wind flow ambit within 1 m. From the analysis results, the smallest wind speed would occur at 95° of angle of circumference, the fan with more fins could occur widespread audio range. With these conditions, make a improvement reference sound source could apply to miniature anechoic rooms.