Low Reynolds unsteady flow simulation around NACA0012 airfoil with active flow control

Abstract

This research numerically elucidates the effects of suction and blowing on the enhancement of unsteady aerodynamic characteristics of flows and their corresponding impact on stall delay over the well-known NACA0012 airfoil at various angles of attack ($12 \le {\text{AOA}} \le 20$) under low Reynolds numbers. For this purpose, an in-house solver written in C++ is developed. The numerical code utilizes the Jameson’s cell-centered finite volume numerical method accompanied by a progressive power-law preconditioning approach to suppress the stiffness of the governing equations. Many numerical simulations are performed over the suction-blowing control parameters, namely, the slot location ($L_{j}$), suction/blowing amplitudes ($A_{j}$), and suction/blowing angle ($\theta_{j}$). Most of the analyses are based on the measurements of the unsteady aerodynamic characteristics behaviors (such as lift, drag, moment coefficients, and stall phenomena) over the airfoil. The numerical results confirm that the unsteady behavior of the flow (vortex shedding) is weakened or approximately removed when suction is used, especially near the leading edge. In all of the test cases, the ratio of the average lift coefficient to the average drag coefficient increases with increasing suction and blowing amplitudes, except in the case of perpendicular blowing. Furthermore, the blowing is more sensitive to the blowing angle compared to the suction. From the suction and blowing results, it is concluded that the former has a more positive impact on the lift and drag characteristics, especially in the case of incompressible flow at Low-Reynolds regimes.