A parametric study on leading-edge slots used on wind turbine airfoils at various angles of attack

In the present work, a narrow span-wise rectangular channel (referred to as a slot) is introduced and drilled near the leading edge of a finite-span cambered airfoil to study its impact on the overall aerodynamic performance. This slot starts from the vicinity of the leading edge and exits from the pressure-side of the airfoil after making a slight turn. NACA 4412 is used as the baseline airfoil profile, and the influence of several geometrical parameters of the slot at the chord-based Reynolds number of 1.6 M, and different angles of attack (AoAs) ranging from 0 to 16° on the lift and drag coefficients are investigated. The effect of slot's width (thickness), inlet angle, and vertical position are studied, and the appropriate range of values for each variable is determined. For one of the best cases examined, a lift coefficient improvement as large as 30% is observed, while the drag penalty is insignificant. Computational fluid dynamics (CFD) method is used for modeling and analysis, and the results are validated against both published data and the data from a set of wind-tunnel experiments.