Effects of confinement on the energy performance of an Archimedes screw using CFD simulation

In the context of the growing development of renewable energy systems, Archimedes screw turbines represent a promising solution for harvesting the kinetic energy of shallow free-surface flows. The system investigated in this study features an innovative configuration: a horizontally oriented Archimedes screw installed at the free surface, partially submerged over half of its diameter, and operating without any hydraulic head. An experimental test rig was developed to assess the influence of key parameters on the turbine performance. The results highlight the major role of the incidence angle on energy conversion efficiency, with an optimal angle of 45° leading to efficiencies of approximately 40% under the tested conditions. Since the experimental conditions are constrained by the dimensions of the laboratory channel and the available discharge, a computational fluid dynamics (CFD) model was developed to explore a wider range of hydraulic and geometric configurations. The numerical model was first validated against experimental data, showing good agreement. Subsequently, parametric studies demonstrated that horizontal confinement is a key design parameter: maximizing the lateral confinement of the screw within the channel significantly enhances the energy efficiency of the system.