Flow Visualization in the Impeller and Diffuser of a Centrifugal Pump using Time-Resolved Particle Image Velocimetry

Abstract

- The present paper describes an experimental study on the flow dynamics within a centrifugal pump impeller. A transparent pump prototype made of acrylic parts was firstly developed for flow visualization purposes. Then, single-phase flow experiments were conducted in different impeller rotational speeds and water flow rates. A time-resolved particle image velocimetry (TR-PIV) system was used as the flow visualization method. As a result, velocity fields were obtained in the whole impeller. They reveal that the flow behaviour is dependent on the pump operational condition. When the pump works at the best efficiency point (BEP), the flow is uniform and the streamlines follow the blade curvature. However, when the machine works at off-design conditions, the flow becomes complex, with the presence of turbulent structures which cause a reduction in the pump performance. This type of result may be useful to validate numerical simulations and support the proposition of new mathematical models, new impeller geometries, among other applications.