The aerodynamic characteristics of airfoils have been researched in higher Reynolds-number ranges more than 10
6, in a historic context closely related with the developments of airplanes and fluid machineries in the last century. However, our knowledge is not enough at low and middle Reynolds-number ranges. So, in the present study, we investigate such basic airfoils as a NACA0015, a flat plate and the flat plates with modified fore-face and after-face geometries at Reynolds number
Re < 1.0×10
5, using two- and three-dimensional computations together with wind-tunnel and water-tank experiments. As a result, we have revealed the effect of the Reynolds number
Re upon the minimum drag coefficient
CDmin. Besides, we have shown the effects of attack angle
α upon various aerodynamic characteristics such as the lift coefficient
CL, the drag coefficient
CD and the lift-to-drag ratio
CL/
CD at
Re = 1.0×10
2, discussing those effects on the basis of both near-flow-field information and surface-pressure profiles. Such results suggest the importance of sharp leading edges, which implies the possibility of an inversed NACA0015. Furthermore, concerning the flat-plate airfoil, we investigate the influences of fore-face and after-face geometries upon such effects.
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