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Turbulence influence on wind energy extraction for a medium size vertical axis wind turbine
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. Halmstad Univ, Dept Construct & Energy Engn, POB 823, SE-30118 Halmstad, Sweden.ORCID iD: 0000-0001-9982-5317
Halmstad Univ, Dept Construct & Energy Engn, POB 823, SE-30118 Halmstad, Sweden.
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.ORCID iD: 0000-0001-8598-2565
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2016 (English)In: Wind Energy, ISSN 1095-4244, E-ISSN 1099-1824, Vol. 19, no 11, 1963-1973 p.Article in journal (Refereed) Published
Abstract [en]

The relation between power performance and turbulence intensity for a VAWT H-rotor is studied using logged data from a 14 month (discontinuous) period with the H-rotor operating in wind speeds up to 9 m/s. The turbine, designed originally fora nominal power of 200 kW, operated during this period mostly in a restricted mode due to mechanical concerns, reachingpower levels up to about 80 kW. Two different approaches are used for presenting results, one that can be compared topower curves consistent with the International Electrotechnical Commission (IEC) standard and one that allows isolatingthe effect of turbulence from the cubic variation of power with wind speed. Accounting for this effect, the turbine stillshows slightly higher efficiency at higher turbulence, proposing that the H-rotor is well suited for wind sites with turbulentwinds. The operational data are also used to create a Cp(λ) curve, showing slightly lower Cp compared with a curvesimulated by a double multiple streamtube model.

Place, publisher, year, edition, pages
2016. Vol. 19, no 11, 1963-1973 p.
Keyword [en]
VAWT; H-rotor; turbulence intensity; power coefficient curve
National Category
Energy Engineering
Identifiers
URN: urn:nbn:se:uu:diva-277352DOI: 10.1002/we.1962ISI: 000386149700001OAI: oai:DiVA.org:uu-277352DiVA: diva2:904731
Funder
StandUpStandUp for Wind
Available from: 2016-02-19 Created: 2016-02-19 Last updated: 2017-11-28
In thesis
1. Noise, eigenfrequencies and turbulence behavior of a 200 kW H-rotor vertical axis wind turbine
Open this publication in new window or tab >>Noise, eigenfrequencies and turbulence behavior of a 200 kW H-rotor vertical axis wind turbine
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Vertical-axis wind turbines (VAWTs) have with time been outrivaled by the today more common and economically feasible horizontal-axis wind turbines (HAWTs). However, VAWTs have several advantages which still make them interesting, for example, the VAWTs can have the drive train at ground level and it has been argued that they have lower noise emission. Other proposed advantages are suitability for both up-scaling and floating offshore platforms.

The work within this thesis is made in collaboration between Halmstad University and Uppsala University. A 200-kW semi-guy-wired VAWT H-rotor, owned by Uppsala University but situated in Falkenberg close to Halmstad, has been the main subject of the research although most results can be generalized to suit a typical H-rotor.

This thesis has three main topics regarding VAWTs: (1) how the wind energy extraction is influenced by turbulence, (2) aerodynamical noise generation and (3) eigenfrequencies of the semi-guy-wired tower.

The influence from turbulence on the wind energy extraction is studied by evaluating logged operational data and examining how the power curve and the tip-speed ratio for maximum Cp is impacted by turbulence. The work has showed that the T1-turbine has a good ability to extract wind energy at turbulent conditions, indicating an advantage in energy extraction at turbulent sites for VAWTs compared to HAWTs.The noise characteristics are studied experimentally, and models of the two most likely aerodynamic noise mechanisms are applied. Here, inflow-turbulence noise is deemed as the prevailing noise source rather than turbulent-boundary-layer trailing-edge noise (TBL-TE) which is the most important noise mechanism for HAWTs. The overall noise emission has also been measured and proven low compared to similar sized HAWTs.

The eigenfrequencies of a semi-guy-wired tower are also studied. Analytical expressions describing the first-mode eigenfrequency of both tower and guy wire has been derived and verified by experiments and simulations.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. 89 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1485
Keyword
VAWT, H-rotor, eigenfrequency, semi-guy-wired tower, noise emission, sound power level, microphone array, turbulence intensity, power curve
National Category
Energy Engineering
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
urn:nbn:se:uu:diva-316385 (URN)978-91-554-9834-4 (ISBN)
Public defence
2017-04-28, Häggsalen, Ångströmslaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:00 (English)
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StandUp
Available from: 2017-04-03 Created: 2017-03-01 Last updated: 2017-04-18

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Möllerström, ErikOttermo, FredricGoude, AndersEriksson, Sandra S.Bernhoff, Hans

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