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Wind tunnel experiments on small-scale model wind turbines: A comparative study using different airfoils
KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-144516OAI: oai:DiVA.org:kth-144516DiVA, id: diva2:713835
Merknad

QS 2014

Tilgjengelig fra: 2014-04-24 Laget: 2014-04-24 Sist oppdatert: 2022-06-23bibliografisk kontrollert
Inngår i avhandling
1. Wind-turbine wake flows - Effects of boundary layers and periodic disturbances
Åpne denne publikasjonen i ny fane eller vindu >>Wind-turbine wake flows - Effects of boundary layers and periodic disturbances
2014 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The increased fatigue loads and decreased power output of a wind turbine placed in the wake of another turbine is a well-known problem when building new wind-power farms and a subject of intensive research. These problems are caused by the velocity gradients and high turbulence levels present in the wake of a turbine. In order to better estimate the total power output and life time of a wind-power farm, knowledge about the development and stability of wind-turbine wakes is crucial.

In the present thesis, the flow field around small-scale model wind turbines has been investigated experimentally in two wind tunnels. The flow velocity was measured with both hot-wire anemometry and particle image velocimetry. To monitor the turbine performance, the rotational frequency, the power output and the total drag force on the turbine were also measured. The power and thrust coefficients for different tip-speed ratios were calculated and compared to the blade element momentum method, with a reasonable agreement. The same method was also used to design and manufacture new turbine blades, which gave an estimate of the distribution of the lift and drag forces along the blades.

The influence of the inlet conditions on the turbine and the wake properties was studied by subjecting the turbine to both uniform in flow and different types of boundary layer in flows. In order to study the stability and development of the tip vortices shed from the turbine blades, a new experimental setup for phase-locked measurements was constructed. The setup made it possible to introduce perturbations of different frequencies and amplitudes, located in the rear part of the nacelle. With a newly developed method, it was possible to characterize the vortices and follow their development downstream, using only the streamwise velocity component.

Measurements were also performed on porous discs placed in different configurations. The results highlighted the importance of turbine spacings. Both the measurements on the turbine and the discs were also used to compare with large eddy simulations using the actuator disc method. The simulations managed to predict the mean velocity fairly well in both cases, while larger discrepancies were seen in the turbulence intensity.

 

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2014. s. viii, 35
Serie
TRITA-MEK, ISSN 0348-467X ; 2014:12
Emneord
wind power, wind-turbine model, wind tunnel, porous disc, hot-wire anemometry, particle image velocimetry, blade element momentum method, large eddy simulations, actuator disc method
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-144475 (URN)978-91-7595-112-6 (ISBN)
Disputas
2014-05-14, D2, Lindstedtsvägen 5, KTH, Stockholm, 10:15 (engelsk)
Opponent
Veileder
Forskningsfinansiär
Swedish Energy Agency
Merknad

QC 20140424

Tilgjengelig fra: 2014-04-24 Laget: 2014-04-23 Sist oppdatert: 2022-06-23bibliografisk kontrollert

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