R. Morel

The Flow Rate Influence on the Interaction of a Radial Pump Impeller and the Diffuser

This article presents the results of a detailed flow investigation within a centrifugal pump equipped with a vaned diffuser. The measurements were made with a laser Doppler velocimeter and were carried out at different operating points. The flow was investigated for different rotor–stator relative positions.

Internal Flow Investigation of a Centrifugal Pump at the Design Point

The unsteadiness of the flow at the leading edge of a vaned diffuser represents a source of low efficiency and instability in a centrifugal pump. Furthermore, the internal flow of the impeller can be affected by asymmetric downstream conditions, which results in extra flow unsteadiness and instabilities. The improvement of machine performances can only be achieved if there is a progress in the comprehension of the nature of the complex flow that develops at the gap between the rotor and the stator.This paper presents the results of LDA investigation of the internal flow of a centrifugal pump equipped with a backswept impeller and a vaned diffuser. The data taken in phase with the impeller rotation are presented as animated frames reconstituting a temporal evolution of the flow in radial planes at the diffuser inlet.

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.

Investigation and Control of Backflow Ahead of a Shrouded Inducer

Incorporating a backflow recirculator is a way to reduce part load instabilities of inducers. Experimental results demonstrate that two devices with simple geometry considerably soften pressure pulsations in suction and discharge pipes associated with part load instabilities, even at low NPSH conditions and low flowrates. This is accomplished with negligible adverse effects on pump performance

Numerical And Experimental Investigation Of Flow Characteristics Of A Centrifugal Impeller

In order to provide a set of validation data for a computational technique, an experimental investigation of the flow field at the exit of a centrifugal pump impeller was carried out. Measurements have been conducted at design and offdesign flow rates. These data are compared to the results of a quasi-three dimensional computational technique. At design conditions, the two sets of data coincide well. While, at low flow rate the numerical model fails to give a prediction of the flow field.