The quantification of the severity of erosion in wind turbine blades is challenging due to the many aspects involved, including meteorology, aerodynamics, materials science, and wind turbine dynamics. A complete model relies on several building blocks, which cover the characterization of precipitation and aerosols, the trajectories of droplets and particles, the operational settings of the wind turbine, and finally the structural response of the leading edge to the large number of impacts across a spectrum of particle sizes and impacts speeds. This paper presents a multidisciplinary model, defining magnitudes representative of erosion severity and formulating their dependencies. The method uses the formula for the erosion incubation time as defined by Springer. The model incorporates the effect of wind velocity and density, particle size, and erosion intensity, and it allows four erosion mechanisms to be considered: rainfall, snowfall, sea spray, and fog. Comparison of the predicted erosion incubation time versus blade inspections shows good qualitative agreement. The equations from the model suggest that the characterization of atmospheric conditions at the site is essential for an accurate estimation of the severity of erosion. Equally important are the material properties, and the impingement process at the leading edge.

Summary of the Blind Test Campaign to predict the High Reynolds number performance of DU00-W-210 airfoil This paper summarizes the results of a blind test campaign organized in the AVATAR project to predict the high Reynolds number performance of a wind turbine airfoil for wind turbine applications. The DU00-W-210 airfoil was tested in the DNW-HDG pressurized wind tunnel in order to investigate the flow at high Reynolds number range from 3 to 15 million which is the operating condition of the future large 10MW+ offshore wind turbine rotors. The results of the experiment was used in a blind test campaign to test the prediction capability of the CFD tools used in the wind turbine rotor simulations. As a result of the blind test campaign it was found that although the codes are in general capable of predicting increased max lift and decreased minimum drag with Re number, the Re trend predictions in particular the glide ratio (lift over drag) need further improvement. In addition to that, the significant effect of the inflow turbulence on glide ratio especially at high Re numbers is found as the most important parameter where the prediction as well as the selection of the correct inflow turbulence levels is the key for correct airfoil designs for the future generation 10MW+ wind turbine blades.

* Chief Engineer of TP400D6 Engine, Engineering and Technology, alfredo.ldiez@itp.es. † Head of Aerodynamics, Aerodynamics Department, Luis.Ruiz@casa.eads.net ‡ Work Package Owner of Front Structure of TP400D6 Engine, Radial structures, javier.castillo@itp.es. § Internal Aerodynamics Engineer, Aerodynamics Department, Raul.Prieto@casa.eads.net 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit 10 13 July 2005, Tucson, Arizona AIAA 2005-4204