Investigation of the effects of vertical multistage pump rotor design parameters on pump performance

Nowadays, the rapid depletion of energy resources brings about environmental problems and concerns about sustainability. In this context, the energy consumption of pumps, which are widely used in daily life, has gained significant attention. One of the most critical components influencing pump performance is the impeller. In this thesis, new impeller designs were developed for a vertical multistage pump to improve performance. The study investigates the effects of varying the number of main blades (from 5 to 8) and adding splitter blades at lengths of 25%, 50%, and 75% of the main blade length on impeller efficiency. To this end, 15 novel impeller designs were generated. Single impeller simulations were performed for the existing and the 15 new impeller designs at the pump's best efficiency point. Then, the most efficient new impeller design and the existing one were individually integrated into the vertical multistage pump, and their performances were comparatively analyzed. These simulations were performed using a numerical model validated with experimental data. The numerical results of the single impeller simulations revealed that the addition of splitter blades at 75% of the main blade length improved both the head and efficiency in all designs. The highest efficiency of 95.43% was observed in the 7-main-blade design with splitter blades at 75% of the main blade length. Compared to the existing impeller, this new design resulted in an 18.15% increase in head and a 1.38% increase in efficiency. In the pump simulations, the new design impeller showed superior head performance but a lower efficiency compared to the existing impeller. It has been determined that the fundamental reason for this situation is the impeller-diffuser compatibility, and new impeller designs should be addressed together with the diffuser.