Numerical Study of the Effects of Maximum Thickness Variations in S1046 Airfoils on the Aerodynamic Performance of an H-Darrieus Wind Turbine

Vertical-axis wind turbines (VAWTs), including H-Darrieus rotors, are attractive for small-scale applications under variable wind conditions. Although airfoil-thickness effects have been examined for conventional NACA and other S-series profiles, systematic maximum-thickness variations of the symmetric S1046 airfoil remain insufficiently documented. This study therefore evaluates a three-bladed H-Darrieus turbine using the reference S1046 airfoil and six controlled maximum-thickness variations (−12.8%, −6.4%, +6.4%, +12.8%, +19.2%, and +32%). Transient two-dimensional URANS simulations, complemented by selected three-dimensional calculations, were performed in ANSYS Fluent 2020 R2 Fluent using the RNG k–ε turbulence model at a constant free-stream velocity of 6m/s and tested TSR values from 0.60 to 2.25. The corresponding local relative Reynolds number varied during rotor motion, with maximum values from 3.27×104 to 6.64×104 over the investigated TSR range. Among the tested configurations, the +19.2% thickness case produced the highest cycle-averaged power coefficient, CP¯=0.2692, comparable with 0.2589 for the reference S1046 airfoil, corresponding to an increase of 3.97%. The results indicate a non-monotonic thickness effect and identify +19.2% as the best-performing configuration among the discrete geometries investigated. The conclusions are restricted to the tested operating conditions and the adopted URANS numerical framework.