Summary:
Wind energy stands out as a crucial renewable resource to meet global energy demands sustainably and mitigate environmental impacts. Blade airfoil profiles and the angle of attack are the primary aerodynamic parameters governing the efficiency of horizontal axis wind turbines (HAWT). This study presents an experimental investigation into the aerodynamic performance of NACA 4415 and NACA 6415 airfoil profiles evaluated at two distinct angles of attack (15° and 30°). The experiments were systematically conducted in an open-type wind turbine test rig at a constant wind speed of 7.5 m/s and an air density of 1.06 kg/m³. Real-time torque and rotational speed data were recorded through a computer-based data acquisition system to construct dimensionless tip speed ratio versus power coefficient performance curves. The experimental results reveal that both blade geometry and the angle of attack significantly influence turbine performance. Model 1 (NACA 4415 at 15°) demonstrated the superior aerodynamic performance among all tested configurations, achieving the highest efficiency and peaking at approximately λ = 4.Conversely, Model 2 (NACA 4415 at 30°) exhibited the lowest efficiency due to premature flow separation and dominant stall behavior. The NACA 6415 profile showed a more stable aerodynamic response at higher operational angles. These findings underline the critical impact of geometric and operational variables on rotor aerodynamics, providing valuable empirical data for the optimized design of small-scale wind turbines.