Effect of Angle of Attack on Flow Control using Traveling Waves

This study numerically investigates the effect of the angle of attack (AOA) on the aerodynamic performance (lift coefficient, C_L, and drag coefficient, C_D) of an airfoil under active flow control using low amplitude surface actuation in the form of backward (opposite to the airfoil's forward motion) traveling waves on the suction side of the airfoil. A NACA0018 airfoil with a low Reynolds number (Re = 50,000) is simulated using large eddy simulations (LES) curvilinear immersed boundary (CURVIB) method at different angles of attack (AOA = 0⁰ to 20⁰). While our previous simulations indicated the effectiveness of backward traveling waves at pre-stall (AOA = 10⁰) and near stall angle of attack (AOA = 15⁰), the effectiveness of these waves at post-stall AOA (AOA = 20⁰) is not understood. The simulation of the baseline case at AOA = 20⁰ is performed first. Afterward, the role of the backward traveling waves with a low amplitude range of a* = 0.001 - 0.002 (a* = a/L; a: amplitude, L: chord length of the airfoil) and a reduced frequency range of f* = 4 - 16 (f* = fL/U; f: frequency, U: the freestream velocity) will be investigated at the post-stall angle of attack (AOA = 20⁰). This work is supported by National Science Foundation (NSF) grant CBET 1905355, and the computational resources are provided by High Performance Computing (HPRC) group at Texas A&M University.