Aerodynamic Performance Characterization of a Drag-Based Elliptical-Bladed Savonius Wind Turbine Rotor

Among the existing wind energy harvesters, the vertical-axis Savonius wind turbine rotor is found to be suitable for small-scale power generation. It is a drag-driven device where the pressure of the fluid stagnating within its blades results in its rotation. The high starting torque and poor operational efficiency of this type of turbine rotor are its distinguishing features. The main geometric and flow parameters that influence its performance are its blade profile, overlap ratio, aspect ratio and Reynolds number (Re). Among these parameters, the blade profile influences significantly on the power production. Recent studies have shown that, choice of an elliptic blade can help in harnessing more wind energy, however, it is desirable to characterize this choice through detailed studies. The present study aims at evaluating the performance of a two-elliptical-bladed Savonius turbine rotor for its dynamic torque and power characteristics. In order to characterize its performances, the developed rotor is experimented in an open circuit low speed wind tunnel. The experiments have been carried out at different Re values so as to estimate the dependence of rotor performance on Re. When the Re is increased from 57310 to 164766, the maximum power coefficient (CPmax) of the turbine rotor has shown an improvement of 43%.

Aeroacoustics behavioral study of Savonius wind turbine

Vertical Axis Wind Turbines (VAWTs) are appropriate for use in populated areas. If VAWTs were installed at residential areas, the generated aerodynamic noise can be harmful in a way or another. Therefore, in the present study, the aero-acoustics of the conventional Savonius Wind turbine was investigated using Computational Fluid Dynamics (CFD). Both the Unsteady Reynolds-averaged Navier-Stokes (URANS) equations and impermeable Ffowcs Wiliams and Hawkings (FW-H) equation were simultaneously solved. The effect of speed ratio was also studied. The results indicate that; the pressure is inversely proportional to the speed ratio. Additionally, the velocity has been increased due to the increase of the tip speed ratio. Finally, it has improved that for the majority of receivers, the overall sound level increases with increasing speed ratio.

Performance assessment and optimization of a helical Savonius wind turbine by modifying the Bach’s section

In this paper, we attempted to measure the effect of Bach’s section, which presents a high-power coefficient in the standard Savonius model, on the performance of the helical Savonius wind turbine, by observing the parameters affecting turbine performance. Assessment methods based on the tip speed ratio, torque variation, flow field characterizations, and the power coefficient are performed. The present issue was stimulated using the turbulence model SST (k- ω) at 6, 8, and 10 m/s wind flow velocities via COMSOL software. Numerical simulation was validated employing previous articles. Outputs demonstrate that Bach-primary and Bach-developed wind turbine models have less flow separation at the spoke-end than the simple helical Savonius model, ultimately improving wind turbines’ total performance and reducing spoke-dynamic loads. Compared with the basic model, the Bach-developed model shows an 18.3% performance improvement in the maximum power coefficient. Bach’s primary model also offers a 12.4% increase in power production than the initial model’s best performance. Furthermore, the results indicate that changing the geometric parameters of the Bach model at high velocities (in turbulent flows) does not significantly affect improving performance.