Effect of Leading-Edge Gap Size on Multiple-Element Wing NACA 43018

Generally, large airplanes are added with more than one high lift device to improve aerodynamic performance. Each configuration of the addition of high lift devices will result in different aerodynamic performances. The added high-lift devices include flaps, leading-edge slats, vortex generators, fences, and others. This study shows the aerodynamic performances of the NACA 43018 wing airfoil with the addition of leading-edge slats and plain flaps in cruise conditions with variations of leading-edge gap size. The angles of attack used include 0°, 2°, 4°, 6°, 8°, 10°, 12°, 15°, 16°, 17°, 19°, and 20°. Numerical simulations have been performed using Ansys Fluent 19.1 with a k-ε Realizable turbulent model. The aerodynamic performance of the configuration that uses the leading-edge slat shows a higher value than the rectangular wing even though the lift and drag coefficients produce lower values. The use of leading-edge slats produces fluctuations, which are indicated by different values of the pressure coefficient, that show the interaction of adding momentum from the main flow from the direction of the leading edge. The increase in the angle of attack causes bubble separation in the leading-edge gap size, which is like a pseudo-body transforming from convergent to smaller.