Aerodynamic Comparison of Smooth Versus Bumpy Airfoil at Different Reynolds Number

View Video Presentation: https://doi.org/10.2514/6.2023-2110.vid Inflatable wings based on bumpy airfoil cross-section are viable candidates for future extra-terrestrial missions as well as hand launched unmanned aerial vehicles (UAVs) due to their inherent foldability as well as mitigated weight penalties. However, there is a need to comprehend the underlying aerodynamics pertaining to bumpy airfoil for a wider acceptance. Current paper makes use of OpenFOAM simulations to compare the subsonic aerodynamics of smooth versus a bumpy airfoil (based on NACA-4318 airfoil) at different Reynolds number (Re) and angles of attack. The simulations make use of steady-state solutions for Re=6x10^6 flow and unsteady simulations for low Re (Re=25000). The paper clearly demonstrates the deleterious effect of bumpy airfoil on the lift and drag characteristics for high Re. The paper demonstrates presence of mitigated flow separation near the trailing edge leading to improved aerodynamic efficiency for bumpy airfoil especially at five degrees angle of attack. Unsteady vortex shedding is also presented for the low Re flow over bumpy airfoil. The paper further makes use of pressure coefficient and flow-field visualization plots to comprehend the underlying flow-physics. Relevant conclusions can be used in the future to carry out design modifications on the baseline geometry and improve the overall aerodynamic performance of inflatable wings.