Lab-scale measurements of wind farm blockage effects

Bartl, Jan; Aasnæs, Camilla H.; Bjørnsen, Joakim R.; Stenfelt, Gloria; Lande-Sudall, David

doi:10.1088/1742-6596/2362/1/012004

Cited by 2 publications

(2 citation statements)

References 25 publications

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“…The three-dimensional velocity vector is measured by a Nortek Vectrino+ Acoustic Doppler Velocimeter (ADV) a sampling frequency of f sample = 200 Hz. Further details on the measurement device and seeding particles are documented in [19]. The thrust forces on the single discs are measured individually on the central and two edge discs of the MR7 setup.…”

Section: Measurement Techniquesmentioning

confidence: 99%

Experiments on upstream induction and wake flow for multirotor wind turbines

Bartl,

Koi,

Skoland

et al. 2023

J. Phys.: Conf. Ser.

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Multirotor wind turbine concepts are increasingly discussed as cost-effective alternatives for floating wind energy installations. When multiple smaller rotors are installed next to each other, the individual rotors experience local blockage from their neighbours. Depending on the rotor arrangement, the flow through and around the multirotors will differ leading to a local variation in axial forcing and power output on the individual rotors. In this lab-scale experiment, we investigate how the spacing between the single rotors in a multirotor of seven actuator discs affects the upstream flow, thrust force distribution and downstream wake flow. Reducing the inter-rotor spacing is observed to cause larger zones of upstream velocity reductions, both in streamwise and lateral direction. Consequently, the difference in thrust force between a locally blocked central rotor and the surrounding rotors also increases for smaller rotor spacing. Measurements of the downstream wake flow behind a multirotor model indicate a lower initial velocity deficit compared to a single rotor. Reduced rotor spacing is found to increase the wake’s initial velocity deficit and turbulence levels. Consequently, the wake recovers faster, resulting in similar velocity deficits independent of the rotor-spacing in the far wake region.

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Section: Measurement Techniquesmentioning

confidence: 99%

Experiments on upstream induction and wake flow for multirotor wind turbines

Bartl,

Koi,

Skoland

et al. 2023

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

show abstract

“…The three-dimensional velocity vector in the wake is measured with the ADV at 200 Hz. A more detailed description of the measurement principles is given in Bartl et al [22]. The Reynolds number based on a single disc's diameter is Re d ≈ 10 5 .…”

Section: Multirotor Modelsmentioning

confidence: 99%

Experiments on the wake flow behind different configurations of multirotor wind turbines

Jørs,

Mjåtveit,

Skoland

et al. 2023

J. Phys.: Conf. Ser.

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Multirotor wind turbine concepts have recently emerged as a promising alternative to conventional turbines. When arranged in farms, the wake flow behind multirotor assemblies becomes an important factor in the cost-of-energy equation. This paper presents a lab-scale experiment on the effect of rotor number, inter-rotor spacing and yaw-misalignment on the wake development behind a simplified multirotor model. The flow characteristics are investigated by towing different arrangements of porous discs in a large water tank while traversing an Acoustic Doppler Velocimeter in the wake. Results show lower initial velocity deficits in a multirotor’s near wake, whereas its far wake is observed to be similar to the one of a single rotor. The wake’s recovery rate is first stimulated by additional shear stresses in between the single rotors, while flattening off further downstream. Measurements on the wake flow behind individual yaw on the single rotors compared to collective yaw on all rotors show a similar deflection of the mean velocity deficit in the wake.

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Lab-scale measurements of wind farm blockage effects

Cited by 2 publications

References 25 publications

Experiments on upstream induction and wake flow for multirotor wind turbines

Experiments on upstream induction and wake flow for multirotor wind turbines

Experiments on the wake flow behind different configurations of multirotor wind turbines

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