Estimating an Optimal Multiple Savonius Wind Turbines Layout by CFD Velocity Pattern Analysis

Abstract

Proper arrangement of multiple VAWT turbines has been known to have increased the overall power efficiency. The challenge is how to optimally place each turbine within a given location such that the overall performance is improved. This paper presents a methodology by which the placement of individual turbine is determined by the location of vortices created by the upstream turbine. This analysis is carried out by using commercial CFD solver via sliding mesh approach. To clearly observe the creation of wake and vortices by an isolated Savonius turbine, the extra fine mesh was defined outside the rotating zone of the computational domain. The resulted velocity pattern generated shows an area of the high vortex created at the tip of advancing blade at a certain rotor angle. However, the returning blade generates a weaker vortex. The placement of consecutive Savonius wind turbine is, therefore, should be at an angle ranges between 20° to 90° with respect to the advancing blade of the upstream turbine. The analyses on two-turbine, three-turbines and nine turbines in V formation have shown an improvement up to 11% in the overall power efficiency.

Enhancement of Wind Farm Power Density by an Oblique Linear Configuration

“…The performance evaluation of the isolated turbine shows that its power coefficient of 0.128 was achieved at the tip speed ratio of 0.7 [18]. Figure 6(a) shows the wake structure behind the isolated turbine at a wind speed of 5 m/s.…”