Large-Eddy Simulations of the flow on an airfoil with leading-edge imperfections

Results of large-eddy simulations of the flow over an airfoil with leading-edge obstacles, mimicking idealized icing geometries, at Re = 200,000 will be presented. A grid convergence study was conducted and the model was validated with experimental data in the literature. Significant variations in structure generation are observed for different roughness geometries. The three-dimensionality of the roughness is found to have a strong impact on the flow: it creates alternating regions of high-momentum and low-momentum fluid, a phenomenon termed "channelling", on both sides of the airfoil. The streamwise coherence of these regions, however, is quite sensitive to the pressure-gradient distribution. Furthermore, the width of these channels is of a similar order as the roughness size, which suggests implications on RANS modelling.