Modification of the aerodynamic chord length of the vertical axis wind turbine to increase its energy efficiency, Lurín Peru

Abstract

Abstract: This paper investigates how the influence of modifying the chord length of NACA 0018 profile blades affects the energy conversion efficiency of a vertical-axis Darrieus wind turbine (VAWT) under the low wind speed conditions recorded in Lurin in 2024. Using 2D-CFD simulations, with a k- epsilon turbulence model, with a constant tip speed ratio (TSR) of 1 and average wind speeds of 2.78 m/s, the chord length was increased from 0.20 m to 0.22 m. This adjustment led to an improvement in torque from 0.267655 N m to 0.314690 N m, which led to an increase in power coefficient (Cp) from 0.24 to 0.29, representing an increase of 17.57%. Furthermore, the results showed that although increasing the chord length improves efficiency, the increase in Cp is moderated by continuing with longer lengths. For example, at a length of 0.24 m, Cp increased to 0.36, but when moving from 0.24 m to 0.26 m, the increase was only 7.03%, reaching a maximum Cp value of 0.38. This behavior suggests a saturation point in the efficiency improvement due to the additional aerodynamic drag generated by longer blades. The results support previous studies, such as that of Pramono et al. [1], who showed that increasing the chord length of the NACA 4415 airfoil improves Cp by 15.68% at low TSRs. Therefore, this study highlights the importance of chord length in the optimization of vertical axis wind turbines under low wind speed conditions to improve the efficiency of small-scale turbines in areas with limited wind resources.