The angle-resolved velocity measurements in the impeller passages of a model biocentrifugal pump

Abstract

Velocity measurements have been obtained in a model of biocentrifugal pump in terms of angle-resolved values in the impeller passages, the volute and the inlet and exit ducts running at the design condition using a laser Doppler anemometer. Water was used as the working fluid. Three impeller geometries have been considered including the 16 forward swept-blade design, 16 straight radial-blade design and 8 backward swept-blade design. The results indicate that all designs showed pockets of recirculating flows and high-shear-stress regions in some passages of the impeller. The splitter plate located along the centre-line of the volute passage was found to be responsible for restricting part of the flows from exiting the impeller to the volute passage. The original intention of the splitter plate was to minimize the imbalance of the radial thrust when the impeller was magnetically suspended. The splitter plate also creates a velocity difference on either side of the splitter plate at the exit duct and may have provided conditions for the formation of spanwise vortices downstream from the exit of the pump. Further development on the biopump should focus on the design integration of the impellers, splitter plate and volute so as to achieve a better pump performance.