Dynamic Stall Control of a pitching airfoil Using Acoustic Black Holes and Synthetic Jets: A Large-Eddy Simulation Study

This research covers a comparative study on the performance of an active and passive flow control method to mitigate flow separation effects of an oscillating NACA 0012 airfoil at a low Reynolds number. Two dimensional transient simulations were carried out to investigate the aerodynamic performance, flow structure, and dynamic stall characteristics of the flow around the airfoil. The airfoil was initially positioned at an angle of attack of 30º and subjected to oscillations of two distinct pitching amplitudes: 5º and 15º. The results indicated that using the synthetic jet as an active flow control method significantly enhances the aerodynamic performance of the tested airfoil. Also, variations in aerodynamic characteristics and comparison of flow structures against the uncontrolled condition revealed that using Synthetic Jet Actuators fundamentally changes the flow physics over the pitching airfoil by effectively suppressing severe flow separation prevalent at low Reynolds numbers. Although ABH can mitigate aspects of large-scale separation and reduce load oscillations, its aerodynamic benefits are comparatively modest and often accompanied by increased drag. The comparative results demonstrate that SJA provides the most effective dynamic-stall control within the tested operating envelope, whereas the ABH offers a low-energy, maintenance-free alternative with limited but potentially useful passive stabilization effects. The findings highlight the importance of understanding unsteady flow physics for designing effective dynamic-stall control strategies and motivate future three-dimensional simulations and experimental validation for practical rotorcraft and wind-turbine applications.