スクロールレス遠心送風機の騒音に関する研究 : 羽根前縁と口金壁面との距離,羽根車入口と出口の面積比,ベルマウス出口形状,ブイルタの位置および口金隙間の影響

概要

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An investigation of both noise and aerodynamic characteristics of a centrifugal fan without scroll casing was carried out with respect to the effects of five parameters: (1) the distance, L_<tm> between blade leading edge and the inner wall of mouthpiece, (2) the location of filter, (3) the gap, δ_m between outer wall of bellmouth and inner wall of mouthpiece, (4) the profiles at outlet of bellmouth, (5) the Areal ratio, A_r of inlet to outlet of the impeller. It was shown that the total pressure and the flow rate of fan lowered as the distance, L_<tm> became large and if the profile at outlet of bellmouth was straight, the lump of sound pressure level produced in the neighbourhood of 1.5kHz band. The agreement between measured value and predicted value of sound pressure level of the turbulent noise was satisfactory.