Experimental Investigation of Aerodynamic Characteristics of NACA 0012 Airfoil With Surface Stippling

<title>Abstract</title> <p> This study focuses on the effect of surface stippling on the aerodynamic characteristics of symmetrical airfoil NACA 0012. Wind Tunnel tests were carried out at a Reynolds number of 2.1 × 10 ⁵ and the range of angle of attack (α) from 0˚ to 90˚ with an increment of 3˚. The pressure distribution over the airfoil is measured by a simultaneous pressure scanner, and the time-averaged pressure is used to calculate the aerodynamic forces acting on the airfoil. Stipplings are checkered patterns that are uniformly impressed over the surface of the symmetrical airfoil in order to study their effect on aerodynamic performance. The results of five different stipplings are then compared with the baseline model to evaluate the effectiveness of stippling. The results reveal that the application of stippling results in smooth stalling and delay of stall. Stippling δ = 0.93% exhibits the greatest aerodynamic performance among other stipplings. Employing stippling is also seen to reduce the fluctuation of lift forces in the post-stall region of the baseline airfoil. The pressure distribution reveals a jagged trend in the pressure on the pressure side of the airfoil for stippling δ = 0.93%. Additionally, attempts are made to explain the aerodynamics of the stippled airfoil using the pressure distribution. </p>