In this study, the aerodynamic performance of wind turbine airfoil profiles operating under low Reynolds number conditions was numerically investigated based on the regional wind characteristics of Erzurum province, Turkey. Considering the low and moderate wind speed regime dominant in this region, the Reynolds number range was selected between 3x104 and 5x105, which is representative of small and medium-scale horizontal-axis wind turbines. Three widely used airfoil profiles, namely NACA 4412, NACA 4415, and NACA 6412, were analyzed using two-dimensional simulations performed with the XFLR5 software. The analyses were conducted over an angle of attack range from 0° to 18°, and the effects of Reynolds number and boundary layer transition characteristics were examined by considering different transition parameters (Ncrit = 6, 8, and 9). Aerodynamic performance was evaluated in terms of lift coefficient (CL), drag coefficient (CD), pressure drag coefficient (CDp), aerodynamic efficiency (CL/CD), and upper surface transition location (Top Xtr). The results indicate that increasing Reynolds number significantly enhances aerodynamic efficiency for all airfoil profiles, primarily due to reduced drag and delayed flow separation. At low Reynolds number (Re = 3x104 , the transition parameter has a pronounced effect on lift generation and drag behavior, where lower Ncrit values lead to earlier transition, reduced pressure drag, and improved lift characteristics. In contrast, at higher Reynolds numbers (Re =5x105), the influence of Ncrit on lift performance becomes negligible. Among the investigated profiles, NACA 6412 exhibits superior aerodynamic efficiency within the Reynolds number range representative of Erzurum wind conditions, making it a favorable candidate for regional wind turbine applications. Overall, this study highlights the critical role of Reynolds number and transition characteristics in low-Reynolds-number aerodynamics and provides valuable insights for airfoil selection and performance optimization of wind turbines operating in low wind speed regions.
Rahim Aytug Ozer (Mon,) studied this question.