Towards development and optimization of the Savonius wind turbine incorporated with a wind-lens

Abstract

Simple design and easy power generation are the two main factors that make the use of vertical axis wind turbines affordable in small scale applications. But, their low efficiency prevents their commercialization. Augmentation techniques can increase the generated power by accelerating the wind speed on the turbine. The present study employs high-fidelity numerical modeling to investigate several important parameters of a flanged diffuser called “wind-lens” installed on a Savonius wind turbine. Six geometrical parameters of the wind-lens including tip clearance, nozzle length, diffuser length, flange length, nozzle opening angle, and diffuser opening angle are studied. Moreover, the sensitivity of the wind-lens to the wind direction is evaluated over a wide range of yaw angles. By using the flow field around the wind-lens, an attempt is made to better understand the effect of each parameter on the turbine performance. Finally, an optimal wind-lens configuration for the Savonius wind turbine is proposed. The optimized wind-lens configuration contributes Cp,max = 0.702 at λ = 1 which exceeds the Betz limit. Also, it reduces the torque ripple factor range from 2<TRFopen turbine<9 to 1<TRFoptimal configuration<2. Therefore, the proposed system can be considered a feasible and cost-effective design for power generation, especially in the built environment.