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Numerical Simulation of a Farm of Vertical Axis Marine Current Turbines
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2010 (English)In: PROCEEDINGS OF THE ASME 29TH INTERNATIONAL CONFERENCE ON OCEAN, OFFSHORE AND ARCTIC ENGINEERING 2010, VOL 3, 2010, 335-344 p.Conference paper, Published paper (Refereed)
Abstract [en]

For commercial applications of marine current turbines, it can be useful to build several turbines close to each other in a farm, similar to wind turbine parks. To create a good farm configuration, the turbines' mutual interaction needs to be studied. Here, to obtain detailed information, several turbines were simulated together using a 2D vortex method. To limit the computational cost, the vortex method was combined with known profile section data for the blades.

First, a single turbine was compared against two turbines in close proximity. The two turbines were tested both with equal and opposite rotational direction, and the two blade pitch angles 0 and 3 degrees were tested. For both a single turbine and the two turbine case, a 3 degree pitch angle gave higher power coefficients than 0 degrees. The differences between 3 and 0 degrees were more significant for the single turbine. In all cases, the two turbine system had higher power coefficient per turbine than the single turbine.

A five turbine park was simulated with three different combinations, one with all turbines on a row, and two with a zigzag pattern, where the difference was that the last simulation had larger turbines than the other two. For 0 degrees incident flow angle, the turbines on the row obtained the highest power coefficient, while the larger turbines in zigzag pattern obtained higher total power. The case with the turbines on the row was most insensitive to changes in flow direction, and for a 30 degree change, the row produced the highest total power as well. By locating the turbines inside a channel, all turbines obtained higher power coefficients, and the increase was largest for the large turbines, which blocked the channel to a larger extent.

Place, publisher, year, edition, pages
2010. 335-344 p.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-142501ISI: 000290556500042ISBN: 978-0-7918-4911-8 (print)OAI: oai:DiVA.org:uu-142501DiVA: diva2:387529
Conference
29th ASME International Conference on Ocean, Offshore and Arctic Engineering Shanghai, PEOPLES R CHINA, JUN 06-11, 2010 ASME, Ocean, Offshore, & Arctic Engn Div
Available from: 2011-01-14 Created: 2011-01-14 Last updated: 2016-04-18Bibliographically approved
In thesis
1. Fluid Mechanics of Vertical Axis Turbines: Simulations and Model Development
Open this publication in new window or tab >>Fluid Mechanics of Vertical Axis Turbines: Simulations and Model Development
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Two computationally fast fluid mechanical models for vertical axis turbines are the streamtube and the vortex model. The streamtube model is the fastest, allowing three-dimensional modeling of the turbine, but lacks a proper time-dependent description of the flow through the turbine. The vortex model used is two-dimensional, but gives a more complete time-dependent description of the flow. Effects of a velocity profile and the inclusion of struts have been investigated with the streamtube model. Simulations with an inhomogeneous velocity profile predict that the power coefficient of a vertical axis turbine is relatively insensitive to the velocity profile. For the struts, structural mechanic loads have been computed and the calculations show that if turbines are designed for high flow velocities, additional struts are required, reducing the efficiency for lower flow velocities.Turbines in channels and turbine arrays have been studied with the vortex model. The channel study shows that smaller channels give higher power coefficients and convergence is obtained in fewer time steps. Simulations on a turbine array were performed on five turbines in a row and in a zigzag configuration, where better performance is predicted for the row configuration. The row configuration was extended to ten turbines and it has been shown that the turbine spacing needs to be increased if the misalignment in flow direction is large.A control system for the turbine with only the rotational velocity as input has been studied using the vortex model coupled with an electrical model. According to simulations, this system can obtain power coefficients close to the theoretical peak values. This control system study has been extended to a turbine farm. Individual control of each turbine has been compared to a less costly control system where all turbines are connected to a mutual DC bus through passive rectifiers. The individual control performs best for aerodynamically independent turbines, but for aerodynamically coupled turbines, the results show that a mutual DC bus can be a viable option.Finally, an implementation of the fast multipole method has been made on a graphics processing unit (GPU) and the performance gain from this platform is demonstrated.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 111 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 998
Keyword
Wind power, Marine current power, Vertical axis turbine, Wind farm, Channel flow, Simulations, Vortex model, Streamtube model, Control system, Graphics processing unit, CUDA, Fast multipole method
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-183794 (URN)978-91-554-8539-9 (ISBN)
Public defence
2012-12-14, Polhemssalen, Ångströmslaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2012-11-22 Created: 2012-11-01 Last updated: 2013-02-11

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Goude, AndersÅgren, Olov

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