Exploring the Optimal Design of Hydraulic Characteristics of Pelton Turbine Nozzle

Abstract

The main function of the Pelton turbine nozzle is to convert the pressure energy of the water flow into kinetic energy and generate a high-speed jet. The quality of the high-speed jet directly affects the energy conversion efficiency of the Pelton turbine. However, current research on nozzle optimization for Pelton turbines only focuses on specific head conditions, without obtaining a general trend of nozzle optimization from low to high heads. In this study, first, multiple internally controlled Pelton nozzles suitable for different heads are designed in line with the empirical formulas and existing models. A coupled CFD-optimization framework was used to evaluate the effects of nozzle angle and spear angle on nozzle hydraulic efficiency and to identify high-efficiency geometric combinations for the selected cases. Across these cases, a head-related trend in nozzle optimization was observed. The results indicate that higher hydraulic efficiency corresponds to the combination of a larger nozzle angle and a smaller spear angle. Across the selected units, the optimal nozzle angle and spear angle tended to decrease as the rated head increased. Correspondingly, lower-head cases generally favored larger nozzle and spear angles, whereas higher-head cases tended to favor smaller angle combinations. Our study can serve as a reference for the hydraulic design of the nozzles of the Pelton turbine and accelerate the design process of the high-efficiency nozzles.