The Effect of Backswept Blading on the Flow in a Centrifugal Compressor Impeller

Abstract

A comparison is made between the flow in two impellers, one with radially ending blades and one with blades backswept by 30°. The two impellers have identical inducers. Measurements are made of the three velocity components and total pressures across five measurement stations within each impeller. The flow in the backswept impeller is dominated by a counter-clockwise vortex which reduces the severity of the shroud boundary layer separation and hence leads to a higher impeller efficiency. The wake is consequently smaller in the backswept impeller but adopts a similar position on the shroud surface at the impeller exit. Analysis of the secondary flow generation reveals the mechanisms responsible for the differences in the flow fields in the two impellers.