Effects of Hub Ratio of Axial Flow Fan on Stator Secondary Flow

抄録

An experimental work is carried out to investigate the hub ratio effects on the magnitudes of the stator secondary flow. A theoretical analysis based on the channel vorticity is made to confirm the experimental results. The outlet angle change due to the secondary motion is significantly affected in the main flow region by a changed hub ratio. This is attributed to the fact that the increase in hub ratio is associated with the approach of two vortices constituting a channel vortex pair, consequently with the enhancement of the induced velocity in that region. The flow rates of the swirling secondary motions are considerably suppressed at a higher hub ratio, while the secondary kinetic energy accounts for an increased fraction of the inlet kinetic energy, and an increased loss is observed particularly in the blade wakes.