Impact of leading edge slat on stall performance of multi-element airfoils

Abstract To ensure the safe takeoff and landing of large commercial aircraft, complex lift augmentation devices have been widely applied. Despite this, even at steep attack angles, leading edge slats on certain multi-element wings can still undergo airflow detachment. This leads to an enlarged wake area behind the slat, diminished airflow circulation around the wing segment, and a decrease in the lift generated by the airfoil. Consequently, this induces intricate air currents between the slat and the main section of the wing, as well as between the main wing and the trailing edge flap, potentially culminating in wing stalls and mishaps. To enhance the takeoff and landing capabilities of multi-element airfoils, the standard multi-element airfoil, 30P30N, was chosen for investigation. By applying the finite volume Reynolds-averaged Navier-Stokes (RANS) approach and utilizing the Fluent module within ANSYS Workbench, the impact of slat position and dimension at the leading edge on the stall behavior of the airfoil was examined. The findings indicate that choosing suitable positions and dimensions for leading-edge slats can efficiently postpone the start of airflow detachment over the wing sections, curb the spread of the airfoil’s wake, and diminish the detachment and blending of slat airflow with the downstream wing section’s boundary layer flow. This substantially improves the aircraft’s aerodynamic efficiency during low-speed takeoffs and landings.