A Numerical Investigation of the Potential of Dimpled Surface Configurations to Improve Aerodynamic and Aeroacoustic Performance of Airfoils

Abstract

This study investigated the potential of dimpled surface configurations to enhance the aerodynamic and aeroacoustic performance of airfoils. Computational Fluid Dynamics (CFD) simulations were carried out on a NACA 0012 airfoil featuring surface dimples, under flow conditions relevant to low-speed aerodynamic applications such as unmanned aerial vehicles (UAVs), light aircraft, and small-scale wind turbines. The simulations were conducted at a Reynolds number of 700,000 and a Mach number of 0.21, representing typical subsonic operating conditions. Two angle of attack, 5° and 10°, were examined to represent attached flow and near-stall behavior, respectively. Aerodynamic performance was evaluated through lift and drag coefficients, while aeroacoustic characteristics were analyzed using Overall Sound Pressure Level (OASPL) with directivity plots and frequency spectrum analysis based on the Ffowcs Williams–Hawkings (FW-H) acoustic analogy. Key findings indicate that the dimpled configuration enhances flow behavior by increasing lift and reducing drag at a 10° Angle of Attack (AoA), primarily through delayed separation and modified stall onset characteristics. Aeroacoustic analysis showed a noise reduction of 2–7 dB at various receiver positions at a 10° AoA, with reductions varying by observer angle and frequency, confirming the directional sensitivity of noise emissions. These insights contribute to the understanding of passive flow control mechanisms and their dual impact on aerodynamic performance and noise reduction in airfoil design