On the Relative Flow Condition behind the Impeller at Axial Flow Pump

Abstract

The author measured the relative flow conditions behind the impeller at an axial flow pump directly with a Pitot-tube rotating with the impeller hub, and investigated the characteristics of relative and absolute flow conditions through the impeller vanes, as flow in a rotating 3-dimensional airfoil cascade, including the effect of boundary layers along the walls of stationary casing and rotating impeller hub. The results show that the flow condition through impeller vanes are affected by the secondary flows induced from these wall boundary layers and peripheral velocities of the flow behind vanes somewhat differ from those obtained by 2-dimensional analysis. The results derived from this experiment were also compared with the mean velocity values measured by the stationary 3-hole cylindrical Pitot-tube, with good agreements.