Operation parameter interaction and optimization of vertical axis wind turbine analyzed by Taguchi method with modified additive model and ANOVA

The present study aims to optimize the design of a vertical axis wind turbine (VAWT) and analyze how the design factors affect the power coefficient of VAWT. The considered factors include the number of blades, angle of attack, airfoil type, tip speed ratio, and wind speed. Computational fluid dynamics (CFD) is used to analyze the flow characteristics and determine the power coefficient. Then the Taguchi method and the modified additive model (MAM) are employed to analyze each factor's influence. As a result, the optimal combination of these factors to give the highest power coefficient is determined. The implementation of MAM analysis is found to enhance the prediction accuracy for the optimal case by exploring the interaction between the factors. The contribution of each factor is evaluated further by the variance analysis method (ANOVA) to examine which factor would be the most crucial one that produces the most significant impact on the VAWT performance. It is found that for a VAWT using NACA 0015 airfoil with 3 blades, the maximum mean power coefficient is 0.421 at an angle of attack 4⁰, tip speed ratio 2, and wind speed 10 m/s. The factors can be ranked in sequence of significance as wind speed, tip speed ratio, angle of attack, airfoil type, and number of blades, in which both the wind speed and tip speed ratio almost exhibit the same impact on the VAWT performance.