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Published September 2022 | public
Journal Article

Large-eddy simulation of helical- and straight-bladed vertical-axis wind turbines in boundary layer turbulence


Turbulent wake flows behind helical- and straight-bladed vertical axis wind turbines (VAWTs) in boundary layer turbulence are numerically studied using the large-eddy simulation (LES) method combined with the actuator line model. Based on the LES data, systematic statistical analyses are performed to explore the effects of blade geometry on the characteristics of the turbine wake. The time-averaged velocity fields show that the helical-bladed VAWT generates a mean vertical velocity along the center of the turbine wake, which causes a vertical inclination of the turbine wake and alters the vertical gradient of the mean streamwise velocity. Consequently, the intensities of the turbulent fluctuations and Reynolds shear stresses are also affected by the helical-shaped blades when compared with those in the straight-bladed VAWT case. The LES results also show that reversing the twist direction of the helical-bladed VAWT causes the spatial patterns of the turbulent wake flow statistics to be reversed in the vertical direction. Moreover, the mass and kinetic energy transports in the turbine wakes are directly visualized using the transport tube method, and the comparison between the helical- and straight-bladed VAWT cases show significant differences in the downstream evolution of the transport tubes.

Additional Information

This research was supported by the National Science Foundation Fluid Dynamics Program under Grant No. 1804214 to D.Y. and Grant Nos. 1802476 and 2038071 to J.O.D. N.J.W. acknowledges support from the National Science Foundation Graduate Research Fellowship. M.G. and D.Y. acknowledge the use of the Sabine and Carya clusters from the Research Computing Data Core (RCDC) at the University of Houston to carry out the numerical simulations and data analyses presented in this manuscript. M.G. and D.Y. also thanks Vincent V. S. Laroche for his contribution to the initial development of the Transport Tube visualization tool. This work was authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding provided by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Wind Energy Technologies Office. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.

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August 22, 2023
October 24, 2023