Wind turbine and actuator disc wake: Two experimental campaigns

Wind turbine and actuator disc wake: Two experimental campaigns

Lignarolo, L.
Ragni, D.
Simao Ferreira, C.J.
van Bussel, G.J.W.

Aerospace Engineering

Aerodynamics, Wind Energy & Propulsion

2015-12-31

The present paper is the summary of 3 years of research on the wake aerodynamics of horizontal axis wind turbine at Delft University of Technology, the Netherlands. In particular, the main results and the conclusions of two experimental campaigns are collected. The underlying research question is: how do the near-wake turbulent flow structures affect the re-energising of the far wake and to what extend is the actuator disc assumption valid for the representation of the near wake dynamics? In the first experiments, stereo particle image velocimetry is used for analysing the turbulent velocity field in the near and transition wake of a small two-bladed wind turbine model. The results showed the important role of the tip-vortex helix instability (leapfrogging) in the mixing process and in the re-energising of the wake. The tip-vortex instability and breakdown, in fact, give rise to a more efficient turbulent mixing. In the second campaign, the same measurement technique is used for acquiring data in the near wake of the wind turbine model and in the near wake of a porous disc, emulating the numerical actuator disc. The results show a good match velocity fields between wind turbine and actuator disc, but show a different turbulence intensity and turbulent mixing. The analysis suggest the possibility to extend the use of the actuator disc model in numerical simulation until the very near wake, provided that the turbulent mixing is correctly represented.

Tip-Vortex Instability
Wind Turbine Wake
PIV Experiments
Wake Turbulence
Actuator Disc

http://resolver.tudelft.nl/uuid:7b6b95d2-076e-4f38-b167-879253805263

UFRGS

Proceedings of the 14th International Conference on Wind Engineering, ICWE14, Porto Alegre (Brasil), June 21-26, 2015

Institutional Repository

conference paper

(c) 2015 The Authors