Wake manipulation on a NACA 0018 airfoil using trailing edge dielectric barrier discharge plasma actuators

Abstract

Active flow control at low Reynolds numbers remains a critical challenge for unmanned aerial vehicles and rotorcraft blades, where severe boundary layer separation on symmetric airfoils degrades aerodynamic performance. This study investigates the aerodynamic effectiveness of localized dielectric barrier discharge plasma actuator (PA) arrays on a NACA 0018 airfoil, specifically positioned starting from the trailing edge and extending upstream with an increasing number of actuators. Wind tunnel experiments were conducted at Re = 3.5 × 10 ⁴ across an angle of attack range of α = 0°–30°, evaluating 1PA, 3PA, 5PA, and 7PA configurations. To resolve localized flow features, a smoke flow visualization method integrated with digital image processing was developed to quantitatively extract the non-dimensional wake width and flow separation position. Among all evaluated layouts, the distributed 7PA configuration demonstrates the most effective flow control, maintaining complete boundary layer attachment up to α = 20°. Consequently, the 5PA array is the next most effective layout for extending the attached flow envelope. However, these multistage setups divide the electrical load, degrading localized momentum injection. Under localized energy management, 3PA array yields significant wake width minimization up to α = 16°, compared to the baseline. Conversely, at moderate angles, the single actuator exhibits highly effective separation control, shifting the separation position downstream by a substantial margin relative to 3PA. This separation delay is driven by concentrating the entire electrical discharge onto a single trailing edge actuator, maximizing localized power to achieve greater control. These findings demonstrate that targeted, localized actuator placement offers highly efficient design alternatives tailored to specific mission requirements.