Numerical Investigation of a NACA 0012 Airfoil with Static-Extended Trailing Edges and Gurney Flaps for Low-Reynolds-Number Wind Turbine Applications

Tiberius S. Gikenyi^1, , Churchill O. Saoke¹ and Joseph N. Kamau¹

¹Physics Department, Jomo Kenyatta University of Agriculture and Technology, Nairobi, 00200, Kenya

Cite this paper:
Tiberius S. Gikenyi, Churchill O. Saoke and Joseph N. Kamau. Numerical Investigation of a NACA 0012 Airfoil with Static-Extended Trailing Edges and Gurney Flaps for Low-Reynolds-Number Wind Turbine Applications. American Journal of Energy Research. 2025; 13(3):86-95. doi: 10.12691/ajer-13-3-2

Abstract

The efficiency of a wind turbine depends on the aerodynamic efficiency of its blade’s airfoil geometry. In this study, we numerically investigate the influence of static extended trailing edges (SETEs) and gurney flaps (GFs) on the aerodynamic characteristics of the NACA 0012 airfoil at a low Reynolds number (Re = 2 × 10⁵). The analysis was conducted using computational fluid dynamics (CFD) based on the 2-dimensional steady and unsteady Reynolds-Averaged Navier-Stokes (RANS/URANS) with the k-ω Shear Stress Transport (SST) model. Three different-sized SETE flap lengths of 10%c, 20%c, and 30%c and three Gurney flaps with heights of 1%c, 2%c, and 3%c were tested at various angles of attack (-4° to 20°). Measurements used the same baseline airfoil at the same Reynolds number to ensure direct comparison between SETE and Gurney flaps. Results show that while the GF 2%c produces high lift, it also causes greater instability beyond stall. SETE 20%c provides superior lift-to-drag ratios, delays separation, and reduces unsteady wake structures, making it an ideal configuration for small-scale wind turbine applications.

Keywords:
NACA0012 Gurney flap Static extended trailing edge CFD low Reynolds number

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