Analysis of the sweeped actuator line method

Journal Article · Fri Oct 16 04:00:00 UTC 2015 · E3S Web of Conferences

DOI: https://doi.org/10.1051/e3sconf/20150501001 · OSTI ID:1352992

Nathan, Jörn ^[1]; Masson, Christian ^[1]; Dufresne, Louis ^[1]; Churchfield, Matthew J. ^[2]

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1. Ecole de Technologie Superieure, Montreal, QC (Canada)
2. National Renewable Energy Lab. (NREL), Golden, CO (United States)

The actuator line method made it possible to describe the near wake of a wind turbine more accurately than with the actuator disk method. Whereas the actuator line generates the helicoidal vortex system shed from the tip blades, the actuator disk method sheds a vortex sheet from the edge of the rotor plane. But with the actuator line come also temporal and spatial constraints, such as the need for a much smaller time step than with actuator disk. While the latter one only has to obey the Courant-Friedrichs-Lewy condition, the former one is also restricted by the grid resolution and the rotor tip-speed. Additionally the spatial resolution has to be finer for the actuator line than with the actuator disk, for well resolving the tip vortices. Therefore this work is dedicated to examining a method in between of actuator line and actuator disk, which is able to model the transient behavior, such as the rotating blades, but which also relaxes the temporal constraint. Therefore a larger time-step is used and the blade forces are swept over a certain area. As a result, the main focus of this article is on the aspect of the blade tip vortex generation in comparison with the standard actuator line and actuator disk.

• Research Organization: National Renewable Energy Lab. (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1352992
• Report Number(s): NREL/JA--5000-68400
• Journal Information: E3S Web of Conferences, Journal Name: E3S Web of Conferences Vol. 5; ISSN 2267-1242
• Publisher: EDP SciencesCopyright Statement
• Country of Publication: United States
• Language: English