Abstract
Savonius wind turbines are characterized by various advantages such as simple design, independence of wind direction, and low noise emission, but they suffer from low efficiency. Numerous investigations were carried out to face this problem. In the present paper, a new idea of the Savonius turbine with a variable geometry of blades is proposed. Its blades, made of elastic material, were continuously deformed during the rotor revolution to increase a positive torque of the advancing blade and to decrease a negative torque of the returning blade. In order to assess the turbine aerodynamic performance, a two-dimensional numerical model was developed. The fluid-structure interaction (FSI) method was applied where blade deformations were defined by computational solid mechanics (CSM) simulations, whereas computational fluid dynamics (CFD) simulations allowed for transient flow prediction. The influence of the deformation magnitude and the position of maximally deformed blades with respect to the incoming wind direction were studied. The aerodynamic performance increased with an increase in the deformation magnitude. The power coefficient exceeded Cp = 0.30 for the eccentricity magnitude of 10% and reached 0.39 for the highest magnitude under study. It corresponded to 90% improvement in comparison to Cp = 0.21 in the case of the fixed-shape Savonius turbine.
Highlights
Vertical axis wind turbines (VAWTs) are typically characterized by lower wind energy-conversion efficiency than commonly used horizontal axis wind turbines (HAWTs)
Similar to other VAWTs, Savonius turbines are independent of the wind direction
The present study focuses on the aerodynamic performance of a novel, efficient design but neither mechanical losses due to friction nor energy losses due to blade deformations are considered
Summary
Vertical axis wind turbines (VAWTs) are typically characterized by lower wind energy-conversion efficiency than commonly used horizontal axis wind turbines (HAWTs) They are often favored in micro power generation due to their simple design, a possibility to locate a generator near the ground, and to accept the wind blowing from different directions [1,2]. Contrary to Darrieus wind turbines, they are characterized by a high starting torque for selected rotor positions They are classified as drag-driven turbines and operate at low rotational speeds, with tip speed ratios not exceeding 2, which makes them safer than HAWTs at strong winds [9]. Savonius turbines are suitable for application in urbanized areas [3]
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