Assessment of the dimples as passive boundary layer control technique for laminar airfoils operating at wind turbine blades root region typical Reynolds numbers

In this work we consider dimples as a possible passive boundary layer control strategy in order to improve the wind turbine blades performance. Due to the complexity of the phenomenon, large Eddy Simulation (LES) is here used to analyze the flow field induced by dimples on the NACA 64(2)-014A laminar airfoil operating at Re = 1.75.10(5). We have selected a laminar airfoil since this kind of airfoils has been considered as successful solution for modem utility scale wind turbines. Experimental measurements were also carried out at the Environmental Wind Tunnel of the University Politecnica delle Marche for the sake of validation of our numerical investigations. LES results provided a good agreement with experimental data. It has been shown that dimples application can produce a reduction of the boundary layer separation; additionally, in all the considered cases, dimples reduce the pressure drag coefficient with a consequent increase of the viscous drag coefficient. (C) 2018 Elsevier Ltd. All rights reserved.