Effects of profile thickness on flap airfoil aerodynamic performance

Based on Spalart-Allmaras( S-A) turbulence model,three kinds of different thickness flap airfoil NACA0012,NACA0015 and NACA0018 at different relative slit width 10‰,15‰ and 20‰ were simulated. The lift and drag coefficient curve and pressure cloud and streamlines at different angle of attack( AOA) ranging from- 9° to 17°were compared. The mechanism that flap influences different thickness airfoil aerodynamic performance was researched. The results showed that,the stalling angle of attack of the airfoil increased as airfoil thickness became larger. The increasing thickness of the flap airfoil increased the stability of fluid flow around the airfoil especially around the flap,made the occurrence point of flow separation separation move toward the trailing edge,reduced the scope and structure complexityof vortex.