Super-hydrophobicity effects on performance of a dynamic wind turbine blade element under yaw loads

Flow characteristics over a dynamic section of wind turbine blade in the presence of super-hydrophobic coatings were studied numerically using computational fluid dynamics method. Assuming a super hydrophobic coating, blade icing can potentially be prevented. Fluids on super-hydrophobic surfaces are moving; so slip velocity exists on their walls. The dynamic motion was in sinusoidal mode that caused deep dynamic stall (DS) phenomenon. The occurrence of DS results in enlarged vortices with high strength of vorticity. These vortices cause overshoot in aerodynamic loads. By applying a super hydrophobic surface on different locations of the airfoil, the DS vortex generation can be definitely affected. Investigation of these effects, is the aim of this paper. There is no study in the literature that analyzed DS in the presence of slip velocities at different locations. Thus, an SD7037 airfoil was simulated at Re approximate to 4 x 10(4) using Transition-SST model. Results demonstrated that as the coating covered the leading edge, DS and vortex formation were postponed and the lift peak reduced about 10.6%; while for airfoil entirely covered by coating, the maximum lift value was augmented 14.6% and DS delayed. Applying slip boundary conditions at trailing edge as well as the pressure side had not considerable changes in cyclic loads. (C) 2019 Elsevier Ltd. All rights reserved.