Rotor-stator interaction in a centrifugal pump equipped with a vaned diffuser

Abstract This paper provides the results of a detailed flow investigation within a centrifugal pump equipped with a vaned diffuser. The measurements made with a laser Doppler velocimeter were carried out at two operating points. Unsteady velocity measurements obtained in phase with the impeller angular position gave access to the relative flow within the impeller channels. Measurements were obtained in the impeller and the diffuser at different measuring planes relative to the diffuser vanes. Results are presented as animations reconstituting a temporal evolution of the flow permitting a better comprehension of the complex flow structure existing between the two interacting blade rows. The analysis of the relative flow field indicates the presence of a jet wake structure. The wake is characterized by low relative velocities localized in the suction side-shroud corner. At the design flowrate, the presence of the vanes seems to have a limited effect on the impeller flow structure, except when the suction side of the blades is facing the diffuser vanes. At the impeller discharge, the time-resolved sequences show that the mixing process of the unsteady and periodic flow leaving the impeller is affected by the presence of the diffuser.