Optimizing Aerodynamic Efficiency of Motionless Paired Airfoil Wind Turbine: A Numerical and Experimental Study

The motionless wind turbine with opposing paired airfoils offers a compact and noiseless alternative to conventional wind energy systems, but its performance remains well below the Betz limit, limiting urban deployment potential. To address this gap, this study conducts a dual-parameter optimization of angle of attack (0–16°) and inter-foil spacing (0.4c–1.0c) for S1210 airfoils, focusing on maximizing suction while minimizing flow asymmetry/separation a critical trade-off unexplored in the prior literature. This study optimizes the aerodynamic efficiency of an S1210 airfoil pair through an integrated approach that combines numerical with experimental analysis. The numerical results show that a reduced spacing of 0.4c amplifies suction but causes premature flow separation and instability, whereas larger spacings of 1.0c produce more stable flow. The optimal configuration is found at an angle of attack of 12° with a spacing of 1.0c, which attains the highest average suction pressure with minimal flow disturbances. Experimental validation with a prototype confirms computational fluid dynamics (CFDs) predictions: a 12° angle of attack yields the highest duct velocity, corresponding to a peak coefficient of performance (COP) of 0.31. The study also identifies that the key design balance to achieve stronger suction requires closer spacing or higher angles, but this comes at the cost of increased flow instability and separation. Conversely, wider spacing improves stability but reduces peak suction. The system’s improved efficiency stems from enhanced venturi effects and controlled flow asymmetry, making the design suitable for scalable urban deployment.