Detailed Hydrodynamic Study for Performance Optimization of a Combined Lift and Drag-Based Modified Savonius Water Turbine

Abstract

A combined lift and drag (CLD) Savonius water turbine is an advanced form of Savonius water turbine that has higher efficiency than the latter. However, its detailed hydrodynamic performance optimization is still unexplored, which is important for its possible future commercialization. The objective of the present work is to perform a detailed hydrodynamic study for performance optimization of the CLD Savonius water turbine at low water speed (characteristic of river stream current) under different design and operating conditions. A parametric optimization using orthogonal experiments is first done to obtain the optimized values of all the contributing design parameters. It is then followed by a detailed computational fluid dynamics (CFD) investigation using ansys fluent software to optimize the hydrodynamic performance of the turbine at the selected design conditions under different operating tip speed ratios (TSRs). Detailed fluidic behaviors including boundary layer features, blade loading, and vorticity structures of the turbine are explored to obtain important performance insights, and power curves of the improved CLD design are also obtained. It is found that the optimized CLD Savonius water turbine has higher hydrodynamic performance than the earlier design of this turbine with a maximum coefficient of power obtained as 0.29 at TSR 0.8.