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

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 (C-P). Using the Taguchi method, the optimization incorporated five control factors: flap position (l(d)), flap length (l(f)), flap angle (theta), flap tip length (l(t)), and angle of the flap tip length (alpha(tip)). The study employed an L-16 (5(4)) 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 C-P predictions were made based on these factors through Regression Analysis (RA). The results revealed optimal configurations of l(d) = 0.65c, l(f) = 0.15c, theta = 70 degrees, l(t) = 0.06c, and alpha(tip) = 8, leading to a C-P 74.01% greater than a conventional VAWT. ANOVA ranked factor contributions as: l(d) > l(t) > theta > l(f) > alpha(tip), with l(d) contributing 39.58% and alpha(tip) 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.