A combined numerical/experimental analysis of the flow in the channel of the vaned diffuser of a radial flow pump

Abstract

The realization and the validation of a simulation in fluid mechanics require an indepth expertise of the modelling process. However, how could the results be guaranteed if they were not accompanied by experimental measurements? On the other hand experimental measurements show some limitations. For example, PIV measurements are limited to certain viewing planes and rarely near the walls. Moreover, this type of results rarely represents instantaneous results but rather a temporal average of the flows over the measurement time. The use of measurement probes is an intrusive method that can modify the flow and which, as the previous method leads to a mean time result. The purpose of this paper is to analyse the experimental results of the SHF pump which have already been the subject of numerous publications by using the results of the CFD which were made with the computing code star CCM +. This paper includes the comparisons between calculations and measurements inside the diffuser which makes possible to comment on the usefulness and the validity of the stationary measurements despite the unsteady nature of the flow. The analysis highlights the influence of leak rates at the entrance of the diffuser and shows a significant influence of these leak rates on the creation of recirculation swirls that disturb the flow at the entrance of some diffuser channels.