Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published June 10, 2018 | public
Journal Article

Vertical-axis wind turbine experiments at full dynamic similarity


Laboratory experiments were performed on a geometrically scaled vertical-axis wind turbine model over an unprecedented range of Reynolds numbers, including and exceeding those of the full-scale turbine. The study was performed in the high-pressure environment of the Princeton High Reynolds number Test Facility (HRTF). Utilizing highly compressed air as the working fluid enabled extremely high Reynolds numbers while still maintaining dynamic similarity by matching the tip speed ratio (defined as the ratio of tip velocity to free stream, λ = ωR/U) and Mach number (defined at the turbine tip, Ma = ωR/a). Preliminary comparisons are made with measurements from the full-scale field turbine. Peak power for both the field data and experiments resides around λ = 1. In addition, a systematic investigation of trends with Reynolds number was performed in the laboratory, which revealed details about the asymptotic behaviour. It was shown that the parameter that characterizes invariance in the power coefficient was the Reynolds number based on blade chord conditions (Re_c). The power coefficient reaches its asymptotic value when Re_c > 1.5 x 10^6, which is higher than what the field turbine experiences. The asymptotic power curve is found, which is invariant to further increases in Reynolds number.

Additional Information

© 2018 Cambridge University Press. Received 21 September 2017; revised 18 December 2017; accepted 21 February 2018; first published online 12 April 2018. The support of the National Science Foundation under grants CBET-1435254 and CBET-1652583 as well as the Gordon and Betty Moore Foundation under grant 2645 is gratefully acknowledged. The authors also wish to thank L. Tang and S. Sudhakar for assisting with the design and manufacture of the wind turbine model.

Additional details

August 19, 2023
October 18, 2023