High-lift simulations of slotted, natural-laminar-flow airfoils

Calculations of the flow around a slotted, natural-laminar-flow airfoil are presented to evaluate the high-lift performance influenced by the position of the aft-element on the trailing edge to free-stream velocity ratio of the fore-element. The analysis is based on Reynolds-Averaged Navier-Stokes transport equations with a modified laminar-turbulent transition model for subsonic flow at representative flight conditions around the multielement airfoil. Results obtained at angles of attack near maximum lift, contribute understanding of stall characteristics and shows maximum aerodynamic efficiency is obtained with a constant slot width between the flap and main element. Calculations of lift as a function of deflection of the sealed micro flap show the aft-element can be an effective control surface. Results obtained with Fowler-flaps are con-sisted to other published data of measured lift curves for typical extended-flap configurations, more specifically, the aforementioned velocity ratio decreases towards the aft-element’s trailing edge indicating that the multielement high-lift system is operating as intended.