Cavitation characteristics and induced runner erosion of a Francis turbine in Southern Xinjiang

Hydraulic cavitation is the primary cause of cavitation erosion in Francis turbine runners. Under the special hydrological conditions prevalent in the desert margin areas of southern Xinjiang, cavitation erosion damage to the runner is particularly severe. Taking the HLJF2062-LJ-200 Francis turbine as the research object, this study employs unsteady numerical simulations of the full flow passage, incorporating the shear stress transport k–ω turbulence model, the volume of fluid multiphase flow model, and the Zwart–Gerber–Belamri cavitation model. It investigates the cavitation characteristics and erosion patterns of the runner under three guide vane openings (14° for low-load, 21° for rated-load, and 28° for high-load conditions) and within a cavitation coefficient range of 0.06–0.20. The results show that cavitation is concentrated on the suction side of the blades near the band side, which constitutes the core cavitation erosion zone. The critical cavitation coefficient increases as the guide vane opening decreases, with values of (σ = 0.06–0.08, 0.08–0.10, and 0.10–0.12) for large, design, and small openings, respectively. The simulation results are consistent with the field measurements of cavitation erosion of the prototype turbine under high-load conditions, providing a theoretical and engineering reference for the operational regulation and anti-cavitation protection of hydraulic turbines in high sediment-laden water regions.