Effect of wind turbine nacelle on turbine wake dynamics in large wind farms

Journal Article · Thu Apr 18 00:00:00 EDT 2019 · Journal of Fluid Mechanics

DOI:https://doi.org/10.1017/jfm.2019.206· OSTI ID:1613268

Foti, Daniel; Yang, Xiaolei; Shen, Lian ; Sotiropoulos, Fotis

Wake meandering, a phenomenon of large-scale lateral oscillation of the wake, has significant effects on the velocity deficit and turbulence intensities in wind turbine wakes. Previous studies of a single turbine (Kanget al.,J. Fluid. Mech., vol. 774, 2014, pp. 374–403; Fotiet al.,Phys. Rev. Fluids, vol. 1 (4), 2016, 044407) have shown that the turbine nacelle induces large-scale coherent structures in the near field that can have a significant effect on wake meandering. However, whether nacelle-induced coherent structures at the turbine scale impact the emergent turbine wake dynamics at the wind farm scale is still an open question of both fundamental and practical significance. We take on this question by carrying out large-eddy simulation of atmospheric turbulent flow over the Horns Rev wind farm using actuator surface parameterisations of the turbines without and with the turbine nacelle taken into account. While the computed mean turbine power output and the mean velocity field away from the nacelle wake are similar for both cases, considerable differences are found in the turbine power fluctuations and turbulence intensities. Furthermore, wake meandering amplitude and area defined by wake meanders, which indicates the turbine wake unsteadiness, are larger for the simulations with the turbine nacelle. The wake influenced area computed from the velocity deficit profiles, which describes the spanwise extent of the turbine wakes, and the spanwise growth rate, on the other hand, are smaller for some rows in the simulation with the nacelle model. Our work shows that incorporating the nacelle model in wind farm scale simulations is critical for accurate predictions of quantities that affect the wind farm levelised cost of energy, such as the dynamics of wake meandering and the dynamic loads on downwind turbines.

• Research Organization: Univ. of Minnesota, Minneapolis, MN (United States); Lockheed Martin Corporation, Littleton, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: EE0002980; EE0005482; AC04-94AL85000
• OSTI ID: 1613268
• Journal Information: Journal of Fluid Mechanics, Vol. 869; ISSN 0022-1120
• Publisher: Cambridge University Press
• Country of Publication: United States
• Language: English

Related Subjects

Mechanics
Physics