Study on Influence of Inner Root Shape of Slat on the Aerodynamic Performance of High-Lift System

For typical large civil transport aircrafts, the improvement of aerodynamic characteristics of high lift devices can significantly improve the overall performance of the aircraft. Geometry details including a slat horn, a nacelle, slat tracks and flap track fairings do have large impacts on the aerodynamic behavior of high lift devices. This paper addresses an investigation on the influence of a geometry detail, the root shape of inner slat. The Computational Fluid Dynamics (CFD) simulations are performed with solving three-dimensional incompressible Reynolds-averaged Navier-Stokes (RANS) equations, and the turbulence is simulated with the k-omega shear stress transport (SST) turbulence model. According to the comparisons of four configurations of different inner root shapes of slat, good consistency can be found at low angles of attack but great difference at high angles of attack for lift coefficients, and different configurations did not differ a lot from each other for drag coefficients. Comparing to configuration 1 and configuration 2, configuration 3 and configuration 4 lead to a larger separation region on upper surface of the wing and thus resulting in the reduction of lift coefficient. In configuration 1 and configuration 2, the vortex caused by the inner root face of the slat have a development path of staying close to upper surface of the wing, resulting in limited separation region. Contrarily in configuration 3 and configuration 4, the vortex caused by the inner root face of the slat develop much higher and spread towards the fuselage and outer side of the wing, which ends up leading to bigger separation region. At the very leading edge of the wing, the relative locations of the inner root face of the slat and onglet of the wing play an extremely important role in affecting the development of flow. The results and analysis will provide a guidance reference in aerodynamic design of inner root shape of slat.