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Santhosh Sabapathy,
- Research Assistant, School of Mechanical Engineering, SASTRA Deemed to be University, Thanjavur, , India
Abstract
Leading-Edge Roughness (LER) strongly dictates boundary layer transition and performance degradation on an airfoil operating at transitional Reynolds numbers, an aerodynamic regime where shear-layer stability mechanisms remain highly complex. The wind tunnel experiments were conducted to investigate the aerodynamic impacts of surface roughness applied over 25% of the chord of a NACA 0018 airfoil using two discrete roughness gradations. Surface roughness induces an early boundary layer trip, causing elevated section drag and reduced maximum lift in the linear regime. However, the rough configurations demonstrate superior lift retention past the conventional stall margin compared to the baseline clean airfoil. Low roughness heights prove particularly advantageous, boosting lift at moderate incidence angles and establishing remarkably smooth, predictable post-stall dynamics. In contrast, higher roughness severely disrupts the laminar boundary layer, capping peak lift performance due to premature shear-layer thickening. Surface pressure and force data confirm that controlled leading-edge roughness functions as a robust passive flow control technique by delaying large-scale flow separation and sustaining partial flow attachment beyond stall. By utilizing shear-layer momentum and forcing early laminar-to-turbulent transition, LER provides the critical turbulent kinetic energy required to resist severe flow detachment. These insights demonstrate that engineered leading-edge surface modifications offer a reliable passive flow control solution to enhance energy capture and structural stability in wind energy applications.
Keywords: Leading-edge roughness, Passive flow control, Aerodynamic performance, Wind turbine, Stall delay
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Journal of Aerospace Engineering & Technology
| Volume | 16 | |
| 02 | ||
| Received | 04/08/2026 | |
| Accepted | 05/08/2026 | |
| Published | 11/08/2026 | |
| Publication Time | 7 Days |