0709 半開放型軸流ファンにおける翼周り流れと騒音特性との関係(OS7-2 流れと音,オーガナイズドセッション)

概要

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The numerical simulations of flow around fan blades were performed by using LES(Large Eddy Simulation)with DSM(Dynamic Smagorinsky Model)about the semi-open type axial flow small fans with non-axisymmetric casing(Normal fan)and with axisymmetric casing(Silent fan). The results of those numerical simulations were compared. Both of fans have low-pressure(Cp≦-0.8)areas in center of suction side surface of blade tip. Especially in normal fan, the low-pressure areas fluctuate by fluctuation of tip vortex. This fluctuation of tip vortex is caused by aerofoil passing small radius parts with separating flow and large radius parts without separating flow. And numerical predictions of the noise level under no-load condition were performed. It was clarified that the numerical result of fourth component of blade passing frequency due to the normal fan casing shape was almost equal to the experimental result.
2009-11-06