Laminar Airfoil Modification Attaining Optimum Drag Reduction by Use of Airfoil Morphing

摘要

In this paper, the effectiveness ofmorphing a laminar airfoil’s leading edge through deformation in order to reducenthe drag at the offdesign angle of attack is investigated. The configuration of the airfoil was deformed under thenstructural restriction that the leading edge is deformedwhilemaintaining both the girth of the deformed part and thenconfiguration of the wing box. The NACA631-012 laminar airfoil was chosen as the baseline airfoil. The Reynoldsnnumber based on the baseline airfoil chord was Rec u0001 3 u0002 106n. Aerodynamic characteristics of the baseline andndeformed airfoils have been investigated using a viscous–inviscid interaction method. It is shown that the leading-nedge deformation is effective in reducing the drag at the offdesign angle of attack, in comparison with the baselinenairfoil. The transition point has been estimated, using a numerical method based on a linear stability theory. Thendeformation is an effectivemeans tomove the transition point aft on the airfoil, and the extension of the laminar flownarea results in a reduction in the drag at the offdesign angle of attack.