抄録
In recent years a compact axial flow fan has been used for cooling of electronic instrument because of its large flow rate. The improvement of fan efficiency and the noise reduction are required considerably. However the electronic parts located upstream fan generate the turbulence of inlet flow, whose effects on fan characteristic and noise are not clarified. In this paper the effects of turbulence of inlet flow generated by obstacle on the fan characteristics and fan noise are investigated. The results are that the fan noise at low frequency region increases with bringing an obstacle located upper region of fan inlet close to a fan and the fan noise at over all frequency region increases with bringing an obstacle located whole region of fan inlet close to a fan, and that the fan efficiency at the large flow rate region is decreased with bringing an obstacle close to a fan.
