Effect of control needle tip and contraction section on the efficiency of Pelton turbine nozzles

This study investigates the influence of nozzle geometry on the efficiency and performance of Pelton turbine micro-hydropower plants. Geometric modeling was carried out for different nozzle configurations, specifically varying the control needle tip angles (55°/130° and 75°/130°), and compared with the original Techydro design (60°/130°). Hydraulic analyses and numerical simulations were conducted to evaluate water flow velocity, energy losses, and nozzle efficiency. Minor truncations of the control needle tip had negligible impact on efficiency, whereas larger truncations increased energy losses and caused deviations in flow direction. Optimization of the nozzle contraction section based on the Wiedosinski curve enhanced efficiency by 5.64% and extended service life by 43.2%. Detailed analysis of nozzle losses along the flow provided critical insights for targeted design improvements. These findings highlight the importance of nozzle design in minimizing hydraulic losses and improving turbine performance, offering valuable guidance for the design and optimization of high-performance micro-hydropower plants.