Experimental and Numerical study on Aerodynamics of Aerofoils at Low Reynolds Number Controlled by Off-Surface Micro-Vortex Generators

International audienceA passive flow control strategy for four different aerofoils (NACA0012, NACA6415, S809 and S8036) operating at low Reynolds number applications, was investigated in the current work. The effect of installing micro off-surface rod device with various cross-section shapes (circular, triangular, square, pentagonal and hexagonal) in the vicinity of aerofoils leading edge at flow condition Re c = 2.5 × 10 5 was experimentally and numerically investigated. A common diameter for each given rod was set to be d/c = 1.34%, where c is the aerofoil chord length. The streamwise in-line and the top cross-stream offset dimensionless spacings were the two parameters that have been considered. Their scaling influence on the flow control effectiveness through aerodynamic loads analysis was examined by mean of wind tunnel measurements. Steady RANS calculations with transition sensitive closure turbulence model (γ − Re θ,t) were further supplemented to provide more insights about this flow control method. The main results revealed that these off-surface micro-vortex generators are very effective in controlling the flow at post stall regime for all aerofoils. First, the parasite drag for rod-aerofoil system is small at low incidence angles for both NACA6415 and S809 wings compared to S8036. In the other hand, significant enhancement in lift coefficient can be achieved at post stall, accompanying by pronounced decrease in drag coefficient for all configurations. In addition, results indicate that the heavy stall can be effectively delayed for higher angles