Effect of blade layout on performance of low specific speed pump operating in turbine mode

Abstract

The very low specific speed pump (nq = 8.9) operated in turbine mode was analyzed. The experimental and numerical studies were carried out in order to show effect of different blade layout on pump-as-turbine (PaT) performance. In total three different impellers were analyzed. One impeller consisting of four main blades and two impellers consisting of four main blades and different arrangement of splitter blades. Either single splitter blade or two splitter blades are placed between each of main blades. While measurements pointed out the main PaT performance, the simulations enable to analyze internal flow fields and point out the mechanisms of performance variation using different impellers. The main aim of this study is to clarify usability of very low specific speed pump for energy recovery in terms of pump as turbine operation or for storage capability in terms of pump-turbine.