Investigation of flow control on an airfoil with a parabolic flap using synthetic jet actuation

Synthetic jets and parabolic flaps are considered effective methods for improving the aerodynamic performance of airfoils in the aviation field. Based on the NACA (the national advisory committee for aeronautics) 0015 airfoil, by integrating a synthetic jet actuator (SJA) with a parabolic flap (PF), this study introduces a novel airfoil configuration—NACA0015-PF-SJA. A systematic parametric investigation is carried out to clarify how the jet momentum coefficient, flap deflection, jet position, and jet angle affect aerodynamic performance. The results show that increasing the momentum coefficient significantly enhances lift and suppresses trailing-edge flow separation, although the efficiency-cost ratio decreases at higher values. The flap deflection angle (δp) has a decisive influence: at δp = 20°, the lift coefficient increases by up to 0.34 at an attack angle is 4°, while at δp = 10°, the lift-to-drag ratio peaks at 46.3. The optimal jet position is found to shift rearward with larger momentum coefficients and forward with increasing angle of attack, reflecting the interplay between jet-induced suction and baseline separation location. The jet angle strongly influences the control mechanism: small angles inject momentum into the boundary layer to delay separation and maximize lift-to-drag ratio, whereas larger angles enhance flow mixing and lift but increase drag. Overall, the synergistic SJA–PF strategy improves lift and reduces drag, offering a promising integrated approach for variable-camber airfoils and active flow control in micro-air vehicle applications.