Influence of the sediment transportation on the performance of a Pelton nozzle: a novel Eulerian approach for a CFD-based comparison

Sediment management strategy is one of the key aspects affecting the environmental impact and the life of hydropower plants, as it must ensure balance between maintaining river continuity and limiting erosion. In order to better understand which is the critical sediments stream that can be admitted through hydropower plants to ensure affordable erosion damages, new CFD models are being continuously studied and tuned to provide valuable instruments for wear prediction under different sediments streams conditions. Working in such direction, the present work aims to provide and apply a steady-state inhomogeneous Eulerian approach to study the three-phase flow occurring inside a Pelton nozzle for different opening conditions and high sediments volume fraction. The CFD set-up has been initially validated in pure water-air conditions by comparing the numerical results obtained in terms of discharge coefficient with the data available in literature concerning the same Pelton nozzle configuration. Then, the CFD model for the simulation of sediments-laden flows has been applied to the same Pelton nozzle geometry and the resulting injector performances and jet character-istics have been compared with the same parameter obtained in pure water-air conditions, highlighting the presence of sediments to cause higher pressure losses and jet modifications that can consequently negatively affect Pelton runner performances.