Solid-liquid flow characteristics of high-head Francis turbine with splitter blades

The sediment in rivers seriously affects the service life and hydraulic performance of turbines. In this study, the behavior of solid-liquid flow in the turbine is investigated for various guide vane openings, employing the Mansouri erosion model along with the mean kinetic energy transport equation. Research shows that in Francis turbines, the extent of wall erosion diminishes as the guide vane opening increases, and the runner area experiences the highest level of wear. Regardless of the opening angle, the guide vane zone consistently represents the primary contributor to hydraulic losses within the turbine, while the runner and draft tube account for the subsequent portions. Within the flow domain of a Francis turbine, turbulent dissipation produces hydraulic losses roughly 100 times higher than those resulting from viscous dissipation, suggesting that the overall hydraulic loss is mainly dominated by turbulent effects. Within the stay vanes and guide vane regions, significant hydraulic losses are primarily located at the leading edges and trailing edges, as well as in the domain adjacent to the shroud. In addition, the guide vane opening significantly affects the formation and behavior of the vortex rope within the draft tube. Hydraulic losses in this region are determined by factors including the guide vane opening, the length of the vortex rope, and the number of runner blades. As the guide vane opening increases, the hydraulic loss in the spiral casing area increases. The research results provide a reference for improving the hydraulic performance of Francis turbines.