Numerical investigation of Savonius wind turbine farms

Abstract

The Savonius vertical axis wind turbine is a simple device, easy to manufacture, has good starting characteristics, and rotates with wind from any direction; nevertheless, it has a lower efficiency than the other wind turbines. The aim of this paper is to numerically explore the non-linear unsteady flow over a conventional Savonius using three dimensional computations with emphasis on the placement of these turbines in a linear array and the effect of an obstacle that acts as a wind deflector. First, an infinite array of turbines is used to study the gap distance between the wind turbine axis rotors. This investigation is conducted via numerical simulations based on the computational fluid dynamics computer program Fluent 14.5. It is found that a gap distance L = 1.4R gives a very good performance. Second, four farms with different number of turbines—from 3 to 21 turbines—are studied. The effect on the power coefficient of the number of turbines in each farm is reported and analyzed. Third, a new arrangement that includes an obstacle at one end of the array of turbines is presented. The best configuration explored in this work increases the power coefficient of each Savonius wind turbine by 82% compared to a single turbine. Finally, the effect of the wind direction for the best configuration is presented and the range of wind angles for which the farm outperforms isolated turbines is calculated.