59 巻 (1993) 558 号 p. 453-459
In order to reduce the noise from a fan for an automobile condenser cooling system, air flow around a blade of the fan was studied by flow visualization and measurements of pressure fluctuations on the blade surface. The pressure fluctuations were found to depend largely on the turbulence intensity of the inflow and to increase the noise. Using two-dimensional aerofoils at different radii from the leading edge, effects of the fineness of the blade nose on the pressure fluctuation were examined, and an aerofoil having the leading edge of a larger radius was found to suppress the pressure fluctuations. A considerable decrease in the turbulence noise was obtained by an axial fan having blades of a blunt nose without any deterioration of the performance.