CFD Simulation of the Flow Characteristics of NACA 0012, NACA 6409, and DHMTU Airfoils in Ground Effect

Ground effect is a phenomenon caused by the presence of a fixed boundary layer below a wing. This results in an effective increase in lift to drag ratio of the airfoil. The available literature on this phenomenon is very limited; also the types of airfoils used in traditional aircrafts are not suited for ground effect vehicles, so a computational study has been done comparing traditional airfoils (NACA series) with ground effect airfoil (DHMTU).In this paper, the aerodynamic characteristics of a NACA 6409, NACA 0012, DHMTU 12-35.3-10.2-80.12.2[1] section in ground effect were numerically studied and compared. In 2D simulation, the flow around each of the airfoils has been investigated for different turbulence models viz. Spalart Allmaras turbulence model and k-e Realizable turbulence models. Lift coefficient, drag coefficient, pitching moment coefficient and lift to drag ratio of each airfoil was determined on several angles of attack from 0 to 10° (0°, 2°, 4°, 6°, 8°, 10°) and different ground clearances (h/c=0.2, 0.4, 0.6, 0.8, 1.0). The results of the CFD simulation indicate a reduction in drag coefficient and an increase in lift coefficient, thus an overall increment in lift to drag ratio of the airfoils, when flying in proximity to the ground. Also DHMTU airfoils have shown a greater consistency in Cm behavior with decreasing height-to-chord (h/c) ratio.Copyright © 2014 by ASME