Aerodynamic Characteristics of the NACA0018 Airfoil

The NACA0018 is a symmetric four-digit airfoil with a maximum thickness of 18% of the chord. Its geometric simplicity and structural depth make it a common reference section for vertical-axis wind turbines, unmanned aircraft, hydrofoils, and validation of computational fluid dynamics methods. This study examines the airfoil's geometry, pressure distribution, boundary-layer development, drag composition, and stall mechanism, and then evaluates a Reynolds-averaged Navier-Stokes simulation over angles of attack from -2° to 16°. At a chord of 1 m and a freestream velocity of 20 m/s, the chord Reynolds number is approximately 1.37 × 10⁶. The SST k-omega model is used because it combines near-wall resolution with improved treatment of adverse pressure gradients. The computed lift-to-drag ratio reaches a maximum of approximately 49 at 7°, while separation is reported near the upper sweep limit of 16°. The discussion shows that the predicted peak efficiency and stall point depend strongly on transition, surface roughness, near-wall mesh quality, and convergence criteria. The results provide a useful baseline, but quantitative validation against matched-Reynolds-number experiments and a mesh-independence study are required before the data are used for design.