Multipoint inverse airfoil design method for slot-suction airfoils

Owing to a renewed interest in advanced-concept transport aircraft with active boundary-layer control (suction and/or blowing), a generalized multipoint method for the inverse design of airfoils with slot suction in incompressible potential flow is presented. The results predicted by theory show good agreement with experiment. Such a design tool could be used interactively to perform rapid trade studies to examine the potential payoff for boundary-layer control as applied to the advanced-concept wings. The method, which is based on conformal mapping, draws on the theory first published by Eppler (Airfoil Design and Data, Springer-Verlag, New York, 1990) and extended by Selig and Maughmer ('A Multipoint Inverse Airfoil Design Method Based on Conformal Mapping,' AIAA Journal, Vol. 30, No. 5, 1992, pp. 1162-1170). The theory predicts an increased lift coefficient and a nonzero value for the inviscid drag coefficient as a result of the slot suction, a price to be paid for the increased lift. The theory also shows that this nonzero value of the inviscid drag coefficient is exactly equal to twice the suction coefficient. Two examples are discussed to illustrate the method and the corresponding change in the aerodynamic characteristics of the airfoils as a result of slot suction.