Numerical investigation of the cavity effects on the passive flow control of NACA0012 airfoil under dynamic stall conditions

In this study, the effects of a cavity on the pitching characteristics of NACA0012 airfoil under dynamic stall conditions were examined numerically and the transient incompressible turbulent flow was simulated in two dimensions. Two different sets of circular cavities with R=0.05c were set at two different positions of x=0.13c and x=0.6c from the leading edge (LE) to investigate the effect of cavity position on the aerodynamic parameters of the airfoil such as lift, drag, and pitching moment coefficients as well as aerodynamic efficiency (lift to drag ratio), using Re=106 and reduced frequency of kf=0.15. Results indicated that the cavity at distant location from the airfoil LE showed a better performance in improving the lift coefficient along with aerodynamic efficiency of the pitching airfoil and the averaged values of the lift coefficient for cavities at x=0.13c and x=0.6c locations increased by 3.57% and 0.18%, respectively compared to the baseline. The averaged value of the drag coefficient for the cavity located at x=0.6c decreased by 3.25% and for the cavity at x=0.13c went up by 3.97% in comparison to the clean airfoil.