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Experimental study on the effect of blade angle on regenerative pump performance

The regenerative pump is a kind of turbomachine that is capable of developing a high pressure rise at relatively low flow rates compared to the centrifugal and axial pumps. Although the efficiency of regenerative pumps is much lower than other turbomachines, they have still been widely used in many industrial applications for high heads at low flow rates. There are a few theoretical models to analyze the performance of regenerative pumps, though, the effect of the blade angle has not been included in any analysis model to date. In this study, the influence of the impeller blade angle and its shape on regenerative pump performance has been experimentally investigated. Straight blades with inclined blade angles of 0°, ± 15°, ± 30° and ± 45° were tested. In addition radial chevron impellers with chevron angles of 15°, 30° and 45° were also included in the present experiments. Hence a total of 10 blade configurations were examined. The pressure head, efficiency and the fluid temperature rise were measured at different flow rates and the results were expressed in appropriate non-dimensional coefficients. From the experimental results, it was found that the pressure head and the efficiency strongly depend on the blade angles as well as the blade geometry. Among all blade configurations tested in this study, the chevron blade exhibited the highest head with reasonably good efficiency. The comparative study shows that there is an optimum chevron angle of around 30° that yields the best performance. These experimental data may be used to include the effect of blade angles in the current performance analysis and design models to widen their applicability.