Aerodynamic Performance Assessment of various NACA Airfoils on a Low Aspect Ratio Wing-in-Ground-Effect (WIGE)

The “ground-effect” is a phenomenon that occurs while aerial vehicles perform flights close to the ground. In case of wing-in-ground-effect (WIGE) aircraft, flight completely consist of operations subjecting to the ground-effect and require special aerodynamic considerations during the design of the vehicle. WIGE aircraft practically bases on the idea of benefiting this effect, therefore the wing, and correspondingly airfoil is the most important geometry to be precisely designed or selected from the beginning of the conceptual design. The objective of this study is to obtain, assess and compare the aerodynamic characteristics of various NACA airfoils in ground-effect with a conceptual design perspective. To this end, a low aspect ratio wing (AR=1.5) was selected as the baseline model and aerodynamic investigation of the design carried out using a Vortex Lattice Method (VLM) solver, comparing and validating with experimental wind tunnel data at Reynold number of 3.4x105. A gird independence study was also carried out to ensure the results were independent from number of panel elements. Subsequently, the airfoils that have been previously known to be used on aerial vehicles (NACA 4412, NACA 23015, NACA 63-415 and NACA 65(2)-215) were applied on the same wing model and analyzed at various ground clearances (h/c) employing the same numerical methodology. The aerodynamic performances of the airfoils were compared in terms of their lift coefficient, drag coefficient and lift-to-drag ratio characteristics.