Superhydrophobic surfaces on supercritical airfoils: mitigating ice formation and enhancing performance

Superhydrophobic surfaces are characterized by low surface energy and micro- to nano-scale roughness. These properties cause fluids to slide over the surface, thereby reducing drag and adhesion, and resulting in a lower drag coefficient. The drag coefficient, adhesion, and shear stress are critical parameters in airfoil performance evaluation. In this study, the effects of slip length and superhydrophobic boundary conditions on the aerodynamic performance of the SC(2)-410 airfoil were investigated numerically at various Mach numbers and altitudes. Superhydrophobic boundary conditions reduce humidity-induced adhesion on the airfoil surface. Comparative analyses were conducted between slip and no-slip boundary conditions, focusing on shear stress as well as drag and lift coefficients. Superhydrophobicity was found to decrease both shear stress and fluid adhesion to the surface. As slip length increases, the drag coefficient decreases while the lift coefficient increases, compared to conventional surfaces. When the Mach number increases from 0.6 to 0.8, the reductions in drag and enhancements in lift become more pronounced. Additionally, altitude significantly affects the calculation of lift and drag coefficients by influencing relative humidity. As altitude increases, relative humidity tends to rise, which leads to an increase in the drag coefficient and a decrease in the lift coefficient. Superhydrophobic surfaces help mitigate the negative impact of humidity on aerodynamic performance.