Comparison and validation of BEM and free wake unsteady panel model with the MEXICO rotor experiment

Abstract

The Model Rotor Experiments under Controlled Conditions (MEXICO) project aimed at creating a database of wind turbine rotor aerodynamic measurements under wind tunnel controlled conditions, for validating and improving wind turbine rotor aerodynamic simulation methods. An extensive measurement program was carried out on a three bladed 4.5m diameter rotor model in the DNW wind tunnel (open jet test cross section of 9.5 x 9.5m). The measurements consisted of pressure distribution along the chord at five spanwise locations of the blade and Stereo Particle Image Velocimetry at certain location of the flow field, including the tip vortex. The measurements included both yawed and non yawed conditions. This work presents some of the results of the MEXICO experiment and a comparison between blade element momentum codes and free-wake unsteady potential-flow codes. The comparison is performed with results for axial and yawed flow cases, with special focus on the aerodynamic effect of yaw. Power and load curves have been obtained, including along spanwise load distribution. Experimental tip-vortex strength decay in the near wake enabled a comparison with tip vortex trajectories in the near wake obtained with the free-wake code.