Multi-criteria decision-making for optimal airfoil selection in small wind turbines at low Reynolds numbers

This research provides a data-driven methodology to choose optimal NACA airfoils suitable for small HAWTs operating at low Reynolds numbers. 36 airfoils at four different Reynolds numbers (421116–673866) were analyzed based on two important parameters: lift-to-drag ratio (Cl/Cd) and its standard deviation. Objective weighting was ensured before evaluation based on three multi-criteria decision-making methodologies: TOPSIS, AHP, and VIKOR. Borda Score was used to aggregate the rankings, and the consistency of the model was checked using Spearman’s correlation. NACA 4521, 4518, and 4421 emerged as high-performance candidates in all scenarios, with high aerodynamic performance and stability according to the results. The method developed in this research is a replicable method to choose the proper airfoil and will enhance the direction towards further optimization incorporating the structural and manufacturing aspects as well.