Noise Reduction Effect of Annular Band of Cross Flow Fan

Dr. Teruo Yamamoto proposed a unique method of noise reduction of a cross flow fan in his patent. He suggested that fan noise could be reduced by using annular band (annular groove) set around the impeller of arbitrary section. We ascertained previously the annular band effect only when it was set around the two ends of impeller. However, the annular band effect is not obvious when it is set at the different position of the impeller. His method is very interesting and seems to have bigger possibility of noise reduction. In this study, the annular band effect is examined by changing the setting position of the band along the impeller.