Pressure Fluctuation in a Vaned Diffuser Downstream from a Centrifugal Pump Impeller

Abstract

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