06 Fakultät Luft- und Raumfahrttechnik und Geodäsie

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/7

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    Tidal current turbine wake and park layout in transient environments
    (2014) Arnold, Matthias; Cheng, Po Wen; Daus, Philipp; Biskup, Frank
    Due to orbital velocities of the waves, the characteristics of tidal current turbines change over time. Therefore the induction factor and subsequent the wake is time dependent. Within the present research this time dependency is investigated by using Computational Fluid Dynamics (CFD) with Virtual Free Surface (VFS) and Actuator Disc (ACD) models. Based on this setup several different wave and current scenarios are simulated and analyzed with respect to the transient velocities in the turbine wake. Special respect is taken to the velocity undulations radiated by the changing apparent velocities in the rotor plane. These undulations move with the wake of the tidal current turbines and increase wave loads on 2nd row turbines in a park. This paper presents an efficient method for simulation of wave and park interactions and investigates dynamic turbine wakes under a large variety of parameters. Based on these simulations a suggestion for a tidal park design with respect to a balance of fatigue loads and power output is concluded.
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    Optimization of a feed-forward controller using a CW-lidar system on the CART3
    (2015) Haizmann, Florian; Schlipf, David; Raach, Steffen; Scholbrock, Andrew; Wright, Alan; Slinger, Chris; Medley, John; Harris, Michael; Bossanyi, Ervin; Cheng, Po Wen
    This work presents results from a new field-testing campaign conducted on the three-bladed Controls Advanced Research Turbine (CART3) at the National Renewable Energy Laboratory in 2014. Tests were conducted using a commercially available, nacelle-mounted continuous-wave lidar system from ZephIR Lidar for the implementation of a lidar-based collective pitch feed-forward controller. During the campaign, the data processing of the lidar system was optimized for higher availability. Furthermore, the optimal scan distance was investigated for the CART3 by means of a spectra-based analytical model and found to match the lidar's capabilities well. Throughout the campaign the predicted correlation between the lidar measurements and the turbine's reaction was confirmed from the measured data. Additionally, the baseline feedback controller's gains were tuned based on a simulation study that included the lidar system to achieve further load reductions. This led to some promising first results, which are presented at the end of this paper.