The Aerodynamic Forces for a Darrieus Rotor With Straight Blades: Wind Tunnel Measurements

Vittecoq, P.; Laneville, A.

doi:10.1016/b978-0-444-42342-9.50049-6

Cited by 2 publications

(2 citation statements)

References 1 publication

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“…Simulations have been shown to accurately predict the experimental power curves of a full-scale rotor tested with variations of the pitch angle [13]. The methods also succeeded in correctly predicting blade torque profiles [29], as measured experimentally by Vittecoq and Laneville [38].…”

Section: Numerical Settings and Test Planmentioning

confidence: 85%

On the influence of virtual camber effect on airfoil polars for use in simulations of Darrieus wind turbines

Rainbird

Bianchini

Balduzzi

et al. 2015

Energy Conversion and Management

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Darrieus vertical-axis wind turbines are experiencing renewed interest from researchers and manufacturers, though their efficiencies still lag those of horizontal-axis wind turbines. A better understanding of their aerodynamics is required to improve on designs, for example through the development of more accurate low-order (e.g. blade element momentum) models. Many of these models neglect the impact of the curved paths that are followed by blades on their performance. It has been theorized that the curved streamlines of the flow impart a virtual camber and incidence on them, giving a performance analogous to a cambered blade in a rectilinear flow. To test the extent of this effect, wind tunnel experiments have been conducted in a rectilinear flow to obtain lift and drag for three airfoils: a NACA 0018 and two conformal transforms of the profile. The transformed airfoils exhibit the virtual camber that the theory predicts is imparted to a NACA 0018 when used in a Darrieus turbine with blade chord-to-turbine radius ratios, c/R, of 0.114 and 0.25. A parallel computational fluid dynamics campaign has been conducted to study the aerodynamic behavior of the same blades in curvilinear flow in Darrieus-like motion with c/R = 0.114 and 0.25, at tip-speed ratios of 2.1 and 3.1, using novel techniques to obtain blade effective angles of attack. The analysis confirms that the theory holds, with the wind tunnel results for the NACA 0018 being analogous to numerical results for the relevant cambered airfoils. In addition, turbine performance is calculated using computational fluid dynamics and a blade element momentum code, for each of the blades in turn. The computational fluid dynamics results for the NACA 0018 agree closely to blade element momentum results for the equivalent cambered airfoil where c/R = 0.25, for both turbine power and blade tangential forces. Agreement between the two methods using geometrically identical blades is poor at both the blade and turbine level for c/R = 0.25. It is concluded that when modeling a Darrieus rotor using blade element momentum methods, applying experimental data for the profile used in the turbine will yield inaccurate results if the c/R ratio is high, in such cases it is necessary to select a profile based on the virtual shape of the blades

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Section: Numerical Settings and Test Planmentioning

confidence: 85%

On the influence of virtual camber effect on airfoil polars for use in simulations of Darrieus wind turbines

Rainbird

Bianchini

Balduzzi

et al. 2015

Energy Conversion and Management

View full text Add to dashboard Cite

show abstract

“…As part of the validation campaign for the development of a vortex model for the Darrieus turbine (DART), Strickland and Nguyen 4 published a dataset from a drag tank facility for a straight bladed VAWT at multiple tip speed ratios. Data were also collected in a wind tunnel test by Vittecoq and Laneville 5 showing normal and tangential load data for a VAWT with a chord to radius solidity ratio of 0.2. While data were only collected at a handful of locations around the azimuth, it provides excellent detail of the potential presence of dynamic stall at tip speed ratios lower than 3.5 for said solidity ratio.…”

Section: Introductionmentioning

confidence: 99%

Estimation of blade loads for a variable pitch Vertical Axis Wind Turbine with strain gage measurements

LeBlanc

Ferreira

2022

Wind Energy

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The blade pitch of a Vertical Axis Wind Turbine can have a profound impact on the aerodynamic loading experienced by the turbine. This in turn impacts the structural loads and the performance of the machine. In order to characterize the effects of changing pitch, studies are conducted with fixed pitch offsets from a neutral pitch position in the open jet wind tunnel of TU Delft. Measurements with strain gages bonded to the turbine struts are used to estimate the normal loading of the blades.The measured behavior gives insights into the sensitivity of the turbine loading to the blade pitch angle. Aerodynamic phenomena associated with VAWTs are evident in the data including dynamic stall and blade vortex interaction. Shifting of turbine blade pitch is shown to alter the azimuthally varying normal loading, causing changes in magnitude and direction of rotor thrust. Frequency responses of the turbine and platform mounting structure are presented for rotating and fixed reference frames, respectfully. The effects of stall due to high pitch offsets is shown to excite higher per rev frequencies in both the rotor normal measurements and platform accelerations. The data sets are made available for validation of numerical models.

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The Aerodynamic Forces for a Darrieus Rotor With Straight Blades: Wind Tunnel Measurements

Cited by 2 publications

References 1 publication

On the influence of virtual camber effect on airfoil polars for use in simulations of Darrieus wind turbines

On the influence of virtual camber effect on airfoil polars for use in simulations of Darrieus wind turbines

Estimation of blade loads for a variable pitch Vertical Axis Wind Turbine with strain gage measurements

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