小型シロッコファンの乱流騒音について

概要

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We made an experimental and a theoretical investigation on the turbulent noise generated by a small sirocco fan. One of the impeller in this experiment has unique structure, which is put the upper impeller with the large inner diameter upon the lower one that has smaller inner diameter and same outer diameter as the upper impeller. This impeller was named dual-cascade impeller. It is expected that the fan efficiency with dual-cascade impeller become higher than the general sirocco fan because of controlled the pressure loss by reversed flow at upper side of the span. Moreover, we suggested the theoretical wake characteristics of the blade in order to predict the turbulent noise; the relative velocity and the width of the wake consisted the separation point on the forward blade. The pressure coefficient and the efficiency of the fan with dual-cascade impeller became higher than the general sirocco fan at the region of high flow rate (φ>0.19). In two types of the small sirocco fans, the sound pressure level of turbulent noise with suggested wake characteristics were predicted within 2.4 dB errors in comparison to measured value.
長崎大学の論文