CFD Investigation of Sediment Transport Effects on Pelton Nozzle Performance Using an Eulerian Multiphase Approach ^†

Sediment management represents a key challenge for hydropower plants, as it requires balancing river continuity preservation with the mitigation of erosion-related damage. To identify admissible sediment loads that ensure acceptable wear levels, reliable numerical tools are required for the prediction of multiphase flow behavior under different sediment transport conditions. In this framework, the present study applies a steady-state inhomogeneous Eulerian approach to investigate the three-phase flow (water–air–sediment) inside a Pelton nozzle under different needle-opening conditions and high sediment volume fractions. The CFD model is first validated under clear water–air conditions by comparing the predicted discharge coefficient with the literature data for the same nozzle geometry. Subsequently, the validated framework is extended to sediment-laden configurations, and the resulting injector performance and jet characteristics are compared with the corresponding clear-water case. The results highlight that the presence of sediments leads to increased pressure losses and modifications of the jet structure, which may adversely affect the hydraulic performance of the downstream Pelton runner.