Performance enhancement of side-by-side hydrokinetic savonius turbines with central and side triangular plates configurations

This study investigates the effects of central and side triangular plates on the performance of side-by-side Savonius turbines operating in narrow canals. Numerical simulations were conducted using transient CFD with the realizable k–ε turbulence model over a tip-speed ratio (TSR) range of 0.2–2.0. Central triangular plates with angles of 72°, 78°, 86°, and 93°, and side triangular plates with angles of 85°, 123°, 149°, and 159°, were evaluated in terms of power coefficient (CP), torque coefficient (CM), velocity and pressure distributions, and turbulent kinetic energy. The results show that the central triangular plates reduce cross-flow interactions and decrease adverse pressure on the returning blade, while the side triangular plates accelerate the flow toward the advancing blade. At the optimal operating condition (TSR = 1), the power coefficient increased by 66.1%, 43.4%, 59.4%, and 86.9% for the central triangular plate configurations of 72°, 78°, 86°, and 93°, respectively. The side plate configuration at 159° increased the power coefficient by 128.6% compared to the conventional turbine. The combined configuration of a 93° central triangular plate and a 159° side triangular plate produced the highest improvement, reaching approximately 342% compared to the conventional turbine.These improvements are mainly attributed to flow redirection, wake interaction, and flow acceleration between the plates and turbine blades, which increase the drag force on the advancing blade and reduce negative torque on the returning blade.