二重翼列遠心ファンの羽根車出口流動様相と騒音特性に関する実験的研究 : 露出度とスクロール吐出角の影響

概要

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The flow at impeller outlet and the fan noise of dual-cascade centrifugal fan (DC fan) had been experimentally investigated with respect to the effects of bare ratio and outlet angle of the scroll casing. These design parameters are effective method for the fan that has to send out a large amount of air. It was found that these design parameters were occurred different phenomena of the flow at impeller outlet, accordingly, the each phenomenon was individually concerned to the fan noise. When the outlet angle became large, the flow velocity passing exhaust duct of the scroll casing that of diffuser was decreased. Then the fan noise also could be decreased because of controlled the relative velocity at impeller outlet near the tongue of the scroll casing. Especially, the both characteristics that of the aerodynamics and the noise of DC fan had available properties than the general multi-blade sirocco fan in the case of large bare ratio. It was considered that the improvement of the noise property concerned with comparably large-scale flow that was brought into being lower frequency at upper side of the impeller.