Aerodynamic design of a high-aspect ratio natural laminar wing for a new short and medium range aircraft

Abstract

Improving the aerodynamic performance of a transportation aircraft is an important contributor to achieve the ambitious goal to attain zero net emission in this transportation sector. The reduction of wing friction drag by delaying transition to keep flow laminar is one of the most promising efforts to succeed here. The oral presentation will show the aerodynamic design and analysis of a highly efficient high aspect ratio wing using natural laminar flow (NLF) shape design intended for a new short and medium range aircraft. Unlike previous NLF designs, the cruise design speed is fully comparable to turbulent wing design in this aircraft category. Nevertheless, the excellent aerodynamic performance of the wing is based on both the vortex drag benefit achieved by the span increase but also the large laminar extent of the wing flow. This is realised by using CATNLF [1, 2] section design. The oral presentation will show the complete design loop from starting with given top level aircraft requirements (TLAR) and deduced aero requirements, initial section design and wing planform studies and resulting in the final section design to maximise the overall aero performance benefit considering all drag components for the entire aircraft mission. The entire design study is based on 2.5D, 2.75D and finally fully inverse 3D CFD simulations. For transition prediction a linear stability eN method [3] was used, which provides N-factors for Tollmien-Schlichting and cross-flow instabilities. During the investigation wing sweep and corresponding aircraft cruise speed were increased step-by-step to keep the achieved laminar extent for a robust wing design at design and also off-design conditions