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Abstract

Thin airfoil theory idealizes the flow around a thin airfoil, and addresses an airfoil of zero thickness and infinite wingspan. It is particularly notable in providing a sound theoretical basis for the important properties of airfoils in two-dimensional flow. This paper gives attention to the gap between the theory and the numerical experiment data in order to make the classification of NACA airfoils and then proposing a simple guideline on the use of the theory. The two-dimensional viscous and incompressible flow around the airfoils is assumed. Several NACA airfoils are considered in the theoretical calculation against the numerical solution. It is found that the theory is applicable for real airfoils within specific range of angle of attack and defined accuracy.