Yaw aerodynamics analyzed with three codes in comparison with experiment

Yaw aerodynamics were computed with three codes of different complexity; 1) The 3D Navier Stokes solver Ellipsys3D using 5–8 million grid points; 2) HAWC3D which is a 3D actuator disc model coupled to a blade element model and using 20–30.000 grid points and 3) HAWC, a finite element based aeroelastic code using The Blade Element Momentum (BEM) model for the aerodynamics. Simulations were performed for two experiments. The first is the field rotor measurements on a 100 kW turbine at Risoe where local flow angle (LFA) and local relative velocity (LRV) at one radial station have been measured in a yaw angle interval of ±60°. The other experiment is the NREL measurements on a 10 m rotor in the NASA Ames 80 ft × 120 ft wind tunnel. LFA were measured at five radial stations and data for the 45° yaw case were analyzed. The measured changes in LFA caused by the yawing were used as the main parameter in the comparison with the models. In general a good correlation was found comparing the Ellipsys3D results with the LFA measured on the NREL rotor whereas a systematic underestimation of the amplitude in LFA as function of azimuth was observed for the two other models. This could possibly be ascribed to upwash influence on the measured LFA.Copyright © 2003 by The American Institute of Aeronautics and Astronautics, Inc. and the American Society of Mechanical Engineers