Study of Periodic Flow in Diffuser Downstream of Centrifugal Pump Impeller.

Abstract

Periodic flows downstream of centrifugal pump impeller in vaneless and vaned diffusers were measured by using a single hole yawmeter with a phase locked sampling method. The flows were also calculated by a inviscid flow analysis with the blade surface singularity method. The periodic variations in calculated static pressure with impeller rotating quantitatively agree well with measured ones. The flow behaviors in the vaned diffuser are discussed with measured and calculated results. The potential interaction between the impeller and diffuser blades appears more strongly than the impeller wake interaction. The appearance of static pressure fluctuations due to the impeller rotating in the fully vaned zone is different from that in the semi vaned zone of the diffuser. The existing of the peripheral surface of impeller outlet and the outlet edge of pressure surface of impeller blade causes the large pressure fluctuations in diffuser.