Application of Vortex Lattice Method for an Analysis on Wake Flow of a Horizontal Axis Wind Turbine Rotor.

This paper describes an analysis of the wake flow behind a horizontal axis wind turbine rotor by means of a vortex lattice method using a free wake model. Rotor blades and their wakes are represented by vortex lattices, which can fit arbitrary blade shapes. The configuration of the wake develops downstream with rolling up, because of the largely decelerated axial flow near the rotor plane and also of the interaction effects within highly skewed vortex sheets. Therefore, a free wake model is adapted with a time marching scheme, where the position of the vortex lattice in the wake is calculated at every time step, using the local velocity, which includes the component induced by the wake. The comparison between the calculated results and the experimental data shows good agreement, especially for the axial velocity distribution in the near wake field.