The influence of leading edge roughness, rotor control and wind climate on the loss in energy production
Christian Bak, Alexander Meyer Forsting, Niels N. Sørensen
Abstract
Abstract This study investigates how losses in energy production from wind turbines are influenced by leading edge roughness, rotor control and wind climates using computations. The performance of a NACA633-418 airfoil with five different damage types was predicted using Computational Fluid Dynamics (CFD) with bumps at the leading edge and grooves into the leading edge. Also, one type corresponding to a repair of a leading edge with an “overbite” was investigated. These airfoil characteristics were used in rotor computations where three different wind climates and five different maximum tip speeds were investigated. The rotor computations reflected that the Annual Energy Production (AEP) increased significantly with the average wind speed on the site. They also reflected that the relative AEP losses due to leading edge damages reduced with increasing average wind speed on sites. For the low wind speed site the losses were between 1% and 4% depending on the extent and the type of the blade damage. For the high wind speed site the losses were between 0.5% and 3%. Furthermore, the bigger the extent of the damages were the bigger the losses were. Finally, it was shown that increasing the maximum tip speed increased AEP and decreased the losses.