Numerical Study of V-Shaped Microgrooves Location on an Aerodynamic Surface for Drag Reduction

One important passive technique for drag reduction is the use of microstructured surfaces. In recent years, the advantages of this method have led some airlines to reduce their fuel consumption by installing microstructured films on aircraft. To understand the physics governing microstructures, this article investigates the effect of V-shaped transverse microgrooves on the NACA 8-H-12 airfoil. For this purpose, grooves with a base and height of 150 μm are placed transversely at eight different locations on the airfoil surface and their effects are investigated at zero angle of attack (AoA) and at velocities of 35, 65, and 100 m/s. The results show that vortices trapped within the transverse microgrooves reduce viscous drag by decreasing shear stress magnitude near the peaks and reversing its direction within the valleys. However, the microgrooves also generate pressure drag due to pressure gradients created within and around the structures. The combined effects of these changes in viscous and pressure drag determine the overall change in total drag. Total drag can either increase or decrease depending on the microgrooved surface area, its location on the airfoil, and the freestream velocity. The maximum drag reduction observed in this study was approximately 6%, achieved with two 200 mm microgrooved surfaces located mid-chord on both the suction and pressure sides at 35 m/s.