Effect of Leading-Edge Tubercle on Aerodynamic Performance of NACA 0021 Airfoil

In the present study, a numerical study has been performed over unmodified NACA 0021 and modified (A2W7.5) NACA 0021 operating at low Reynolds number using Spalart–Allmaras (SA) and k-kl-ω RANS models. The unsteady three-dimensional (3D) simulations are performed over unmodified NACA 0021 and modified (A2W7.5) NACA 0021 at Re 120,000 for a range of angle of attacks. The performances of airfoils are evaluated through aerodynamic lift, drag, and pressure coefficients. It has been observed that there exist some advantages due to the tubercles. The maximum lift value is less for modified airfoil as compared to unmodified one. But the stall nature of this airfoil is gradual. The simulation results depict that there is significant downstream shift in the separation location particularly at high angles like 20°. The result shows that for the same amount of lift at higher angles, drag reduces for modified airfoil. © 2018, Springer Nature Singapore Pte Ltd.