3.3 Effect of axial inter-distance
For large axial inter-distance (Fig. 10) the axial flow velocity is
quite uniform downstream IGV vanes, even at low flow rates. If this gap
is reduced further an important blockage is observed from mid-span to
tip sections of blade, hence concentrating the flow toward the lower
part of blade. This blockage induced by the proximity of IGV and blades
is related to the aerodynamic loadings over the suction sides and the
overturning of flow streamlines. Meanwhile, this blockage causes
alteration of flow incidence which reduces from hub to mid-span while
increases from mid-span to blade tip, and subsequently inducing high
losses.