チューブラー遠心送風機の入口偏流による干渉騒音の予測

概要

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The Characteristics of the periodic fluctuation of the tubular centrifugal fan were calculated by the discrete vortex method. By using the results, the interference noise caused by the interaction between the blade of impeller and the inlet distortion flow was predicted. It was pointed out that the fluctuations of the relative velocity at the inlet of impeller and the circulation around the blade have almost the same influence on the interference noise. The noise source is gathered near the leading edge of the blade. So the coefficient is introduced to use the averaged value of pressure fluctuation over the blade instead of the distributed noise source. The coefficient of averaging and the chord-wise correlation length do not varied with the degree of the distortion of the inlet flow. The interference noise levels by the prediction give good agreement with those by experiments. The inlet distortion flow has to be decreased under 1 percent to reduce the interference noise level to the turbulent noise level.
長崎大学の論文