COMPUTATIONALLY INEXPENSIVE FREE VORTEX METHOD TO OBTAIN VORTEX CORE POSITION IN THE WAKE OF A HORIZONTAL AXIS WIND TURBINE

Abstract

This work aims to develop a free wake model, allowing quick simulation of flow through a horizontal axis wind turbine. The rapidity of computation is particularly interesting when this aerodynamic model is integrated with complementary mechanical and electrical models in order to study the unsteady behavior of the complete chain of energy transfer in the wind turbine. The proposed model takes into account both the tangential and longitudinal vorticity of the vortex system formed behind the rotor. The employed vortex system replaces the helical wake close to the wind turbine by a series of vortex rings and the far wake by a semi-infinite vortex cylinder. By taking into account the root vortex, the proposed model is used to study the development of the near wake of a horizontal axis wind turbine for different speeds of rotation. The shape of the near wake as well as the position of the trailing vortices are compared with particle image velocimetry experimental results for a low-power wind turbine tested in the wind tunnel of Arts et Métiers-ParisTech. The model shows a good agreement between the calculation and the experience.