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. 2025 Feb 4;15(1):4290.
doi: 10.1038/s41598-025-87000-z.

Multi-slotted airfoil design for enhanced aerodynamic performance and economic efficiency

Mohamed A Aziz  1 , Mohamed A Khalifa  2 , M A Abdelrahman  3 , Haitham Elshimy  4 , Ahmed M Elsayed  5
Affiliations

Multi-slotted airfoil design for enhanced aerodynamic performance and economic efficiency

Mohamed A Aziz et al. Sci Rep. .

Abstract

Recently, slotted airfoils have been introduced as a passive flow control approach. The slotted airfoil method resulted in stall delay and enhanced the lift coefficient. The single-slot airfoil is unable to delay stall if the flow is injected downstream of the separation point at the stall angle of attack. A multi-slot airfoil ensures air is injected along the airfoil suction side, delaying stalls over a large range of AOA. The current study focuses on enhancing wind turbine blades' efficiency by utilizing a novel multi-slot NACA23012C airfoil design as a passive control approach. A numerical study of the optimal grid number was carried out, followed by validating the numerical model with previous experimental results in the literature. The numerical study is followed by a study of the effect of the number of airfoil slots: one, two, three, four, five, and six. The characteristics of the flow field were analyzed to explain the benefit of applying multi-slotted on the aerodynamic performance of an airfoil with a high AOA at Reynolds number 2.74 × 105. The findings showed a significant improvement in the lift coefficient values and the delayed stall AOA for multi-slot airfoils compared to the clean and single-slot airfoils. Increasing the slots number is effective up to four slots. The four-slot airfoil improved lift by 15.8%, and the two slots achieved a 22.31% CL/CD increase. Future work could optimize slot geometry, validate findings experimentally, and study dynamic and 3D effects.

Keywords: Multi slotted airfoil; NACA 23012C; Numerical study; Passive flow control; Wind turbine.

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Conflict of interest statement

Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Airflow at high AOA for (a) clean airfoil with separated boundary layer and (b) multi-slotted airfoil with attached boundary layer.
Fig. 2
Fig. 2
Airfoil with synthetic slots geometry definition.
Fig. 3
Fig. 3
Various slotted airfoil configurations studied.
Fig. 4
Fig. 4
Schematic of (a) 2D airfoil CFD control volume, (b) CFD domain with boundary conditions, (c) structured grid for CFD entire domain, (d) structured grid around a slotted airfoil, and (e) structured grid through the slot.
Fig. 5
Fig. 5
(a) Variation of Aerodynamics coefficients with gid numbers, (b) Cp variation at AOA 8° with different cell numbers.
Fig. 6
Fig. 6
(A) The current numerical CL and CD at Re = 1.15 × 106 with several turbulence models compared to experimental measurement by (B) RMS errors for several turbulence models.
Fig. 7
Fig. 7
Variation of aerodynamic coefficient with AOA for different slotted airfoil configurations (a) CL, (b) CD, (c) CL/CD.
Fig. 8
Fig. 8
Pressure and streamline contours of clean and slotted NACA 23012C section at different AOAs.
Fig. 9
Fig. 9
Pressure coefficient distribution of NACA 23012C section at different slot numbers and AOAs.
Fig. 10
Fig. 10
Velocity profile at six locations along the airfoil suction side with AOA 18°.
Fig. 11
Fig. 11
Velocity profile at six locations along the airfoil suction side with AOA 24°.
See this image and copyright information in PMC

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