Investigations on Axial Flow Fan Impellers With Forward Swept Blades

Abstract

The forward swept blades are expected to reduce the accumulation of boundary layer fluid resulting from the effect of centrifugal forces, near the tip region of an axial flow impeller blade. An experimental study was carried out on three sets of impeller blades with different forward sweep, keeping the blade element profile geometry the same. It is seen from the comparison of the overall performance of the impellers with swept and unswept blades that the swept blades operate more efficiently than the unswept blades, especially at low volume flows. Moreover, the blade element stall is delayed, if the blades are swept forward. An analysis of the experimental results shows that forward sweep effectively reduces the deteriorating effects of the radially outward boundary layer flow in the tip region.