Improvement of vertical axis wind turbine performance by using the optimized adaptive flap by the Taguchi method

Abstract

ABSTRACT In light of the growing use of Vertical Axis Wind Turbines (VAWTs) in urban settings, research is increasingly focusing on passive control methods to enhance VAWT efficiency. This study aims to refine VAWT performance by optimizing an advanced turbine design equipped with an adaptive flap on the blade, focus on the power coefficient (CP). Using the Taguchi method, the optimization incorporated five control factors: flap position (ld), flap length (lf), flap angle (θ), flap tip length (lt), and angle of the flap tip length (αtip). The study employed an L16 (54) orthogonal array design. At a 2.62 tip speed ratio (TSR), all models underwent computational fluid dynamics (CFD) simulation. The influence of each factor was assessed using the ANOVA (Analysis of variance), and CP predictions were made based on these factors through Regression Analysis (RA). The results revealed optimal configurations of ld = 0.65c, lf = 0.15c, θ = 70°, lt = 0.06c, and αtip = 8, leading to a CP 74.01% greater than a conventional VAWT. ANOVA ranked factor contributions as: ld > lt > θ > lf > αtip, with ld contributing 39.58% and αtip only 1.34%. Predictions from the RA aligned well with the numerical findings. In conclusion, the adaptive flap design enhances performance by expanding the wake and amplifying the vortices behind the turbine blade.