High-Reynolds-Number Design of a Wing Section Including Control of Boundary Layer Properties

Abstract

A novel high Reynolds number design for airfoils with an application in the outer part of a modern transport aircraft wing was conducted within the frame of the German technology research programme LuFo III “High Lift Configurations. Three airfoils were designed for transonic free flight conditions by four-point optimisations accounting for aerodynamic performance and boundary-layer properties using the optimisation software Pointer and the MSES code for the aerodynamic analysis. An existing optimisation environment was extended for controlling the boundary layer shape parameter and specific objective functions were developed. For similar aerodynamic performance, the designed airfoils realised different boundary layer developments by different shape parameter distributions on the upper surface with a slow, a moderate, and a steep rise towards the trailing edge. The shape parameter at the trailing edge was kept constant for all airfoils. The design was validated by DLR-TAU RANS computations showing that lift, drag, pressure distribution, and skin friction distribution were in good agreement with the MSES prediction. However, the precise prediction of the skin friction at the trailing edge exhibited differences probably caused by the differing modelling of the boundary layer flow. Comparisons of the shape parameter distributions confirmed the designed boundary layer properties.