Numerical Analysis of the Interaction of Savonius Vertical Axis Wind Turbines in Tree-type Cluster Configuration

The continuous commissioning of wind energy harvesting machines has impacted the last years‘ clean energy share in the global energy demand. Vertical axis wind turbine clusters suitable for urban architecture integration are part of the market where not only the performance parameters are of utmost importance, but also their aesthetic design, low noise, and low-cost operation. Starting from the 3D geometry of a tree-type Savonius vertical axis wind turbine cluster with 27 rotors, a 2D computational domain is extracted including 9 turbines. The aerodynamic influence of the array pattern is numerically evaluated with Ansys Fluent URANS simulations. Vorticity magnitude contours together with torque and power plots for each rotor are thoroughly analyzed. The rotor position in the array along with the operating regime in terms of TSR, prove to be responsible for the power extraction capability of each turbine. While the output power of 4 out of 9 rotors belongs to the 130–140 W range for TSR 0.7 to 1, one rotor reaches 200 W in the high TSR regimes due to positive field effects. In contrast, detrimental coupling with the neighbouring turbines is encountered by 2 rotors resulting in low power output figures below 50 W in the low TSR regimes.