The Effect of Flow Rate on Passage Flows in Centrifugal Impellers

Abstract

Flow measurements were taken in unshrouded and shrouded centrifugal impellers with 10 radial blades at the outlet by using a five-hole pressure probe. Measurements were taken for a flow rate corresponding to nearly zero incidence angle, and two other flows with reduced and increased flow rates. It was shown by these measurements that, along the passage, the low-energy region tended to move from the middle blade-to-blade position toward the suction side near the casing surface in the unshrouded impeller, and from the suction-side/shroud corner toward the hub side in the shrouded impeller. These shifts of low-energy region were observed upstream in the passages of both impellers, as the flow rate decreased.