Effect of Blade Surface Roughness on Performances of Axial Flow Fans with Different Blade Cambers

Abstract

In order to clarify the influence of blade camber ratio on the effect of surface roughness on axial flow fan performances, three rotor blades with different camber ratios have been designed to the same fan specification, and performance tests have been conducted by changing sand grain roughness of blade surface. The axial fan rotor with a larger camber ratio indicates greater deterioration of performance with an increasing surface roughness. In the case of small camber ratio, the torque coefficient of the fan does not change with roughness. Also the effect of blade surface roughness has been investigated from the viewpoint of boundary layer theory.