The wake structure of a wind turbine - comparison between PIV measurements and free-wake calculations

摘要

Rotor aerodynamic prediction codes remain inaccurate, as many of the features of the wake flow are not yet fully understood, or are simply unknown. In the present work, this problem has been addressed by comparing the results of a sophisticated free-wake numerical code with wake measurements made using the technique of Particle Image Velocirnetry (PIV). Unique images have been obtained at the University of Edinburgh, using PN to capture wake images at model scale. Detailed maps of velocity and vorticity have thus been obtained in the wake of a number of small-scale models. Simultaneously, the sophisticated free-wake numerical code ROVLM has been developed at the University of Stuttgart. The code has been successfully applied in previous aerodynamic and aeroacoustic EU research projects. The aim of this comparison has been to highlight those areas of current theory where wake modelling is weakest.