The effect of tip speed ratio on a vertical axis wind turbine at high Reynolds numbers

  • Colin M. ParkerEmail author
  • Megan C. Leftwich
Research Article


This work visualizes the flow surrounding a scaled model vertical axis wind turbine at realistic operating conditions. The model closely matches geometric and dynamic properties—tip speed ratio and Reynolds number—of a full-size turbine. The flow is visualized using particle imaging velocimetry (PIV) in the midplane upstream, around, and after (up to 4 turbine diameters downstream) the turbine, as well as a vertical plane behind the turbine. Time-averaged results show an asymmetric wake behind the turbine, regardless of tip speed ratio, with a larger velocity deficit for a higher tip speed ratio. For the higher tip speed ratio, an area of averaged flow reversal is present with a maximum reverse flow of \(-0.04U_\infty\). Phase-averaged vorticity fields—achieved by syncing the PIV system with the rotation of the turbine—show distinct structures form from each turbine blade. There were distinct differences in results by tip speed ratios of 0.9, 1.3, and 2.2 of when in the cycle structures are shed into the wake—switching from two pairs to a single pair of vortices being shed—and how they convect into the wake—the middle tip speed ratio vortices convect downstream inside the wake, while the high tip speed ratio pair is shed into the shear layer of the wake. Finally, results show that the wake structure is much more sensitive to changes in tip speed ratio than to changes in Reynolds number.


Vortex Reynolds Number Particle Imaging Velocimetry Wind Tunnel Shear Layer 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



The authors wish to thank Matthew Glasstone and Allen Schultz for their experimental assistance. We thank Antonio Posa and Elias Balaras for much insightful discussion and many helpful suggestions. Thank you to The Metro Washington Chapter of the Achievement Rewards for College Students (ARCS) Foundation and the McNichols Foundation for their financial support of my education.

Supplementary material

Supplementary material 1 (mp4 9878 KB)

Supplementary material 2 (mp4 8516 KB)

Supplementary material 3 (mp4 4487 KB)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.Department of Mechanical and Aerospace EngineeringThe George Washington UniversityWashingtonUSA

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