Abstract
A screw-type centrifugal pump was manufactured to carry solids primarily and its impeller has a wide flow passage. However, the effect of flow passage shape on delay of the choke due to entrained air has not been enhanced yet. For that reason, we carried out the pump performance experiment under air-water two-phase flow condition with different impeller tip clearances and void fractions. At a narrow tip clearance, we obtained the result that the pump head became partially higher in two-phase flow than that in single-phase flow near the best efficiency point in low void fraction region. And the loss became much larger in low flow rate region at both tip clearances. Moreover, we have observed the internal flow patterns by using a stroboscope and a halogen sheet light. Then, we have investigated the influences of flow patterns on two phenomena above-mentioned and mechanism of choking its flow passage.
