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Location of aerodynamic noise sources from a 200 kW vertical-axis wind turbine
Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). (Energy)
Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). Uppsala University, Uppsala, Sweden. (Energy)ORCID iD: 0000-0001-9982-5317
Sound View Instruments, Borrby, Sweden.
Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS). (Energy)
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2017 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 400, 154-166 p.Article in journal (Refereed) Published
Abstract [en]

Noise levels emitted from a 200 kW H-rotor vertical-axis wind turbine have been measured using a microphone array at four different positions, each at a hub-height distance from the tower. The microphone array, comprising 48 microphones in a spiral pattern, allows for directional mapping of the noise sources in the range of 500 Hz to 4 kHz. The produced images indicate that most of the noise is generated in a narrow azimuth-angle range, compatible with the location where increased turbulence is known to be present in the flow, as a result of the previous passage of a blade and its support arms. It is also shown that a semi-empirical model for inflow-turbulence noise seems to produce noise levels of the correct order of magnitude, based on the amount of turbulence that could be expected from power extraction considerations.

Place, publisher, year, edition, pages
London: Elsevier, 2017. Vol. 400, 154-166 p.
Keyword [en]
Vertical-axis wind turbine, H-rotor, Noise, Microphone array, Beamforming
National Category
Energy Engineering Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:hh:diva-33813DOI: 10.1016/j.jsv.2017.03.033OAI: oai:DiVA.org:hh-33813DiVA: diva2:1094278
Funder
StandUpStiftelsen Olle Engkvist Byggmästare
Available from: 2017-05-09 Created: 2017-05-09 Last updated: 2017-05-16Bibliographically approved
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
Identifiers
urn:nbn:se:hh:diva-33834 (URN)978-91-554-9834-4 (ISBN)
Public defence
2017-04-28, Häggsalen, Lägerhyddsvägen 1, Uppsala, 13:00 (English)
Opponent
Supervisors
Funder
StandUp
Available from: 2017-05-11 Created: 2017-05-10 Last updated: 2017-05-17Bibliographically approved

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