Abstract

For harvesting wind energy, especially at low-velocity regions, Savonius vertical-axis wind rotors are usually preferred. Among other variants of the vertical-axis wind rotors, the Savonius rotor has become an attractive candidate as a small-scale stand-alone system due to its direction independency, ease of fabrication and the absence of yaw-mechanism. The present paper attempts to study the effect of corrugated blades on the performance of a conventional Savonius rotor. The corrugation is a bio-inspired concept derived from the dragonfly wings. As reported in literature, the corrugation applied in the chord-wise direction of the airfoil improves the lift characteristics. This lift improvement is caused by the trapped vortices inside the corrugation that promotes a low-pressure region over the leading edge and suction surface of the airfoil. This concept of corrugation and its effect has been applied to the blades of a conventional Savonius wind rotor to improve its torque characteristics. In this paper, a rotor with corrugated semicircular blade profiles is studied by two-dimensional (2D) transient numerical simulation in ANSYS FLUENT using shear stress transport (SST) k-ω turbulence model. The simulations are conducted in the range of 5 m/s to 7 m/s to suit the lower wind velocities of the Savonius rotor. The torque and power coefficients of the corrugated semicircular-bladed rotor are calculated at the rotating conditions. Further, the pressure and local torque distributions over the corrugated blade surfaces are obtained and analyzed to understand the torque mechanism of the rotor with corrugated blade profiles. In order to have a direct comparison, the study has also been carried out for semicircular-bladed rotor without corrugation.

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