Optimization of hub geometry of a double suction pump as a turbine

The double suction pump as a turbine plays an increasingly important role in energy recovery and hydropower generation due to its stable operation and simple structure. Therefore, optimization research on it is of great significance. In this article, the unique design of the hub structure in double suction pumps consisting of conventional half hubs is proposed to be modified to extend the hub until the outer diameter and analyzed. Numerical calculations based on the shear stress transport (SST) k-ω model and verified by experiments show that the full hub impeller exhibited superior hydraulic performance, with an efficiency about 1%–2% higher than the half hub impeller under all operating conditions. Entropy production theory is employed to analyze energy losses, we found that full hub impellers, compared to half hub models, significantly reduce energy loss, with a maximum reduction of about 5.45%. In addition, the full hub impeller reduces turbulence losses up to 5.32% on the one hand and increases friction losses up to 4.52% on the other hand, but turbulence losses account for a larger proportion of the total losses, so the overall efficiency is improved.