Aerodynamic design of Natural Laminar Flow supersonic aircraft wings

Aerodynamic design of Natural Laminar Flow (NLF) for supersonic aircraft wings was conducted by using 3-D CFD analysis and boundary layer stability analysis. There are two main subjects for NLF wing design. One is that the wing of the sub-scaled unmanned supersonic experimental aircraft of National Aerospace Laboratory (NAL) was designed to improve the L/D (Lift/Drag) ratio. The wing sections were designed especially to reduce skin friction drag which amounts to nearly half of the total drag. For this purpose, we designed the wing sections to remain laminar flow as far as possible using 3-D CFD solver and 3-D laminar boundary layer stability analysis code and 2-D inverse design method. The other is that the simple sweep-back wing was designed to delay a transition due to cross flow instability in consideration of spanwise pressure distribution.