Improving the Fluid–Structure Interaction for Effective Energy Harvesting in Vertical-Axis Wind Walls with Symmetrical Configuration

The Wind Wall is a symmetric multi-VAWT system designed for efficient wind energy harvesting using Ugrinsky-type blades that are arranged in a compact, geometrically balanced layout to improve flow uniformity and torque stability and reduce pulsating loads. This study uses CFD simulations to determine the optimal helix angle and turbine spacing by analyzing the aerodynamic moment coefficient (Cm), effective velocity (Ve), and corresponding pressure-induced torque trends for stationary turbine configurations and proposes a simplified correlation linking Ve, turbine diameter, and spacing. The results show that a helix angle of 20–30° and symmetric spacing yield the highest performance, with the optimal angle increasing the time-averaged Cm by approximately 831% compared to the closest-packed case. These findings address the critical impact of improper spacing and sub-optimal twist angles in compact multi-turbine systems and provide the first combined CFD-based assessment of the helix angle and spacing for a symmetric Ugrinsky-blade Wind Wall, contributing a practical spacing–velocity relationship for future design and deployment.