Abstract
The method for measuring the shear stress distributions over the fan blade is proposed by using the oil-film visualization technique combined with the image analysis. The visualization experiment is carried out in a water tank and the surface velocity of the oil-film over the blade surface is measured by cross-correlation algorithm applied to the two images with a certain pattern displacement. The transformation of surface velocity to shear stress is made by a well known shear stress distribution over a rotating disk, which allows the correction of centrifugal force effect on the surface velocity of the oil film. The shear stress distribution and the limiting streamlines over the fan blade are measured and the performance of the fan is studied.
