Aircraft Wing Aerodynamic Efficiency Improvement Using Longitudinal Spanwise Grooves

Abstract

Passive flow control techniques are the advanced boundary surface modifiers to improve the aerodynamic performance by keeping the flow attached. The overall aim of this study is to implement semi-circular grooves over the NACA 2412 wing at various orientations, to keep the flow attached along with the relative aerodynamic performance changes of baseline and groove wing. Numerically simulation over a Low Aspect Ratio wing of order 1 with variant angle of attack, at an operating velocity of 30 m/s, and Re of 4.4 × 105 is presented. Grooves over a baseline wing disturb the flow behavior, thereby creates turbulence by producing rotating small eddies. These rotating vortices keep the flow attached for longer time by re-attaching the separated flow with enhancement in L/D characteristics. Variant of longitudinal grooves has been employed over the wingspan at different x/c location (1) near leading edge (0.2C), (2) near trailing edge (0.8C), (3) mid-span (0.5C), (4) triplet location (0.2C, 0.5C, 0.8C). The models are designed using CATIA V5R20, and ANSYS Fluent helps to simulate the flow behavior, vortex development and aerodynamic performance difference between models. From the simulation study, it is clearly understood; the baseline wing shows massive boundary flow separation on the suction side of the wing beyond 14° AOA with immediate stalling. The presence of these longitudinal grooves enhances the stalling characteristics by keeping the flow attached up to 18° AOA. In all the optimized wing models, the L/D shows at least 0.05% improvement compared to baseline wing. However, the aerodynamic characteristics show pronounced results in the case of the triplet groove wing. It proves that creating roughness over smooth wing shifts the stalling angle and also improves the lift in that region with minor turbulence drag reduction.