エアセパレータ付き軸流ファンの騒音  [in Japanese] Noise from an Axial-flow Fan with an Air Separator  [in Japanese]

In order to develop a high-performance and low-noise axial-flow fan, an effect of an air separator equipped guide vanes at the inlet was experimentally investigated. Using the air separator, the noise levels of the blade passing frequency and its higher harmonics were increased. The modified air separator, expanded the distance from the rotor blade tip to the guide vane in the air separator, reduced these noise levels without reducing the pressure rise of the fan. It was confirmed that potential interaction between the pressure field around the rotor tip and the guide vane affected the noise at the maximum efficiency point, and that the influence of the interaction between the velocity fluctuation at the rotor tip and the guide vane on noise is strong at the operating limit of the fan.