Numerical and Experimental Study on Aerodynamic Characteristics of Basic Airfoils at Low Reynolds Numbers

摘要

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 C_(D) _(min). Besides, we have shown the effects of attack angle α upon various aerodynamic characteristics such as the lift coefficient C_(L) , the drag coefficient C_(D) and the lift-to-drag ratio C_(L) /C_(D) 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.