Comparison of BEM and Full Navier-Stokes CFD Methods for Prediction of Aerodynamics Performance of HAWT Rotors

The essential contribution of this study consists of comparing between two radically different aerodynamic methods which were applied to predict the aerodynamic performance of horizontal axis wind turbines (HAWTs). The classical blade element momentum theory (BEM) and full rotor geometry computational fluid dynamics (CFD) based on the Reynolds Averaged Navier-Stokes (RANS) approach were used in order to discover their strengths and weaknesses for a range of wind speeds where the flow over the rotor varied from fully attached flow to massively separated flow (i.e. Tip Speed Ratio, TSR = 4-10). New MEXICO measurements (Model rotor EXperiments In COntrolled conditions) from German-Dutch wind tunnel (DNW) which were recently carried out between June and July 2014 are used for validating and testing the both BEM and CFD codes. In general, it was founded that, RANS-CFD simulations give good agreements with uniform accuracy level in all studied cases, whereas BEM calculations give reasonable results only at low wind speeds and it fails at higher wind speeds due to the separated flow conditions.