Centrifugal pumps are utilized in various industrial fields, and there is a strong demand to develop a usable one even under the air-water two-phase flow condition with the high inlet void fraction. Authors have investigated air-water two-phase flow performance of centrifugal pump. As the results, we have developed a centrifugal pump for air-water two-phase flow operation. The impeller, having double rotating cascades of the inner and outer with higher outlet blade angle and the installation of diffuser cascade downstream of impeller outlet yields the further improvement of air-water two-phase flow performances. In the present paper, under the case of water single-phase flow condition, we examine the flow distribution in the impeller by EFD (LDV measurement) and CFD (CFX-code simulation) analysis. By comparing the results between the test impellers with no diffuser cascade and with diffuser cascade, we discuss the relation between the impeller performances and flow distribution in the impeller.
