Mitigation of flow separation and debris using a bio-inspired micro-textured coating*

Flow separation in airfoils brings with it an array of negative effects, including reduced lift and increased drag, vibration and noise. Active methods to mitigate flow separation, i.e. synthetic jets and plasma actuators, require extra space and power for sensing and auxiliary systems. Here, we test the functionality of a bio-inspired micro-surface for mitigation of flow separation by carrying out experiments on an S835 airfoil at Re_c ≈ 500,000. The surface consists of an array of mushroom-shaped micro-pillars with a height of approximately 85 µm and a tip diameter of 75 µm. Such coating is applied on the top of the airfoil and the leading edge of the airfoil. Characteristics of the microstructures could also lead to self-cleaning properties and reduce the impact of insect debris at the leading edge of the airfoil. Preliminary data reveal a substantial decrease in the size of the recirculation bubble and up to a 60% decrease in the area of the fluid with reverse flow. Furthermore, viscous losses from turbulence generator appear to be unaffected by the bio-inspired surface coating.