Abstract
Helical tip vortices in the wake of a wind turbine have been investigated in this study. To elucidate the near-wake flow field of the wind turbine, the wake has been explored in the Reynolds number (Re) range 1000 ≤ Re ≤ 5000 using qualitative dye flow visualization and quantitative digital particle-image velocimetry techniques. Flow visualization showed the dye getting trapped in the shape of spirals surrounding the helical vortex cores. It was found that the helical vortex core size was increasing with downstream distance. It was also found that the normalized stream-wise component of the wake velocity decreased with increasing tip-speed ratios. The results indicate that vorticity peaks at the center of the core and it decays as the vortex moves downstream, showing that the viscous dissipation is active even at length scales of approximately 5 diameters.
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Acknowledgements
The author expresses his sincere thanks to the technical staff of the Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst for manufacturing wind turbine blades and their assistance in building experimental set-up employed in this study.
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Varshney, K. Characteristics of helical tip vortices in a wind turbine near wake. Theor Appl Climatol 111, 427–435 (2013). https://doi.org/10.1007/s00704-012-0672-4
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DOI: https://doi.org/10.1007/s00704-012-0672-4