Development of a mixed-flow pump for a small-scale hydro power test facility

Abstract

A holistic method for the design of a mixed-flow pump was sought, but was not readily available in open literature. A design and evaluation methodology for a mixed-Flow pump has been developed by making use of open literature that covers the design of the different mixed-flow pump components. In the present study, the inlet parameters of a small-scale hydraulic turbine, to be tested in a hydraulic test cycle, is used. Utilising these values as an example data-set, a generic mixed-flow pump design and evaluation methodology is developed to serve as a first-iteration design of a mixed-flow pump with any set of desired outlet parameters which result in a dimensionless specific speed of 1.9 ≤ Nₛ ≤ 2.5. A prototype mixed-flow pump was built and commissioned in a testing cycle as to test the compatibility of the individually designed mixed-flow pump components. CFD sim-ulations were also executed and the results were compared to the physical test results to form the bulk of the evaluation process. All obtained results correlated with one another and confirmed that the volume flow rate design parameter was achieved. The delivered head, however, was found to be about 3m higher than what was designed for. The development of the methodology proved to be successful to a great extent with minor complications and proved to be an adequate first design iteration for a specific mixed-flow pump.