Innovative modification of the NACA 0012 airfoil for enhanced lift and aerodynamic efficiency: CFD and experimental validation

Enhancing airfoil performance through passive, energy free flow control is a key goal in modern aerodynamics. This study investigates a modified NACA 0012 airfoil incorporating a rectangular convergent duct at the leading edge. The internal passage accelerates lower surface airflow through the Venturi effect, creating a localized low-pressure region that enhances lift and stabilizes the boundary layer without external power input or mechanical actuation. Experiments in a subsonic open circuit wind tunnel at 10 m/s (Re ≈ 1.5 × 10 5 ) and steady state CFD simulations using the k – ω SST model were conducted under identical conditions. Both results confirm that the ducted configuration improves aerodynamic efficiency in the pre stall regime, achieving a 10 %–13 % increase in lift, 10%–15 % reduction in drag, and 30 %–35 % improvement in lift to drag ratio compared with the baseline NACA 0012. CFD and experimental findings agree within 10 %–15 % across all angles of attack. Flow field visualization shows a high momentum jet emerging from the duct outlet and a persistent low-pressure core beneath the lower surface, demonstrating Venturi driven acceleration that delays separation and sustains lift. The proposed passive internal flow control concept provides a simple, lightweight, and energy free means to enhance aerodynamic efficiency for low Reynolds number applications such as unmanned aerial vehicles and small wind energy systems.