Simulation and optimization of Airborne Wind Energy Systems for offshore applications using aerodynamic models and Large Eddy Simulation by Jean-Baptiste CRISMER

Airborne Wind Energy Systems (AWES) consist of tethered wings that harvest power from the wind. Pumping-mode AWES are considered here: they generate power during the reel-out phase and consume a fraction of this power during the reel-in phase. The understanding of the wake shed by such devices is of primary importance when considering wind farms, yet it has not been much studied so far, and even less so when considering kites with soft curved wing.

In this presentation, LES is used to study the wake generated by AWES. Two types of wings are considered: a straight wing, modelling a reference rigid wing AWES, and a curved wing accounting for leading edge inflatable kites. Both types are modelled using an actuator line method. A wake analysis and comparison for purely circular trajectories reveals that the wake of curved wings tends to be stronger and to recover faster. This is attributed to the curved geometry of the wing and to the effects of its tips.

Then, the case of a straight wing AWES flying a realistic trajectory with reel-out and reel-in phases is simulated. Two trajectories are considered, and the number of loops for the reel-out phase is shown to influence significantly how turbulence is released in the wake.