Experimental validation of a ducted wind turbine design strategy

Kanya, Benjamin; Visser, Kenneth D.

doi:10.5194/wes-3-919-2018

Cited by 29 publications

(20 citation statements)

References 21 publications

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“…CC BY 4.0 License. input is discussed by Kanya and Visser (2018)). For α and z rotor /l, an increase in the design variable causes flow separation inside the duct and a significant drop in the power output.…”

Section: Resultsmentioning

confidence: 99%

Maximal power per device area of a ducted turbine

Bagheri-Sadeghi¹,

Helenbrook²,

Visser³

2021

Preprint

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Abstract. The aerodynamic design of a ducted wind turbine for maximum total power coefficient was studied numerically using the axisymmetric Reynolds-averaged Navier-Stokes equations and an actuator disc model. The total power coefficient characterizes the rotor power per total device area, rather than the rotor area. This is a useful metric to compare the performance of a ducted wind turbine with an open rotor and can be an important design objective in certain applications. The design variables included the duct length, the rotor thrust coefficient, the angle of attack of the duct cross-section, the rotor gap, and the axial location of the rotor. The results indicated that there exists an upper limit for the total power coefficient of ducted wind turbines. Using an Eppler E423 airfoil as the duct cross-section, an optimal total power coefficient of 0.69 was achieved at a duct length of about 15 % of the rotor diameter. The optimal thrust coefficient was approximately 0.9, independent of the duct length and in agreement with the axial momentum analysis. Similarly independent of duct length, the optimal normal rotor gap was found to be approximately the duct boundary layer thickness at the rotor. The optimal axial position of the rotor was near the rear of the duct, but moved upstream with increasing duct length, while the optimal angle of attack of the duct cross-section decreased.

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Section: Resultsmentioning

confidence: 99%

Maximal power per device area of a ducted turbine

Bagheri-Sadeghi¹,

Helenbrook²,

Visser³

2021

Preprint

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“…However, in principle, a side force can be exerted without the use of any power. This is analogous to the application of ducts, which have been shown to provide multiple-fold increases in turbine power output by shaping the streamlines around the turbine [ 23 ]. Here, we propose using a side force to achieve a similar effect.…”

Section: Theoretical Considerationsmentioning

confidence: 99%

Use of streamnormal forces within an array of tidal power harvesters

2022

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Tidal energy is a renewable and promising energy source. Turbines are deployed under water in marine channels where there is a fast tidal current. The first arrays have only recently been deployed and there is no consensus yet on the optimal array design. In this paper, we explore whether the maximum harvestable power can be increased by using harvesters or flow deflectors that exert a side force in the streamnormal direction to oppose the expansion of the streamtube. The power harvesting and the side force exertion are modelled with sink terms in the two-dimensional Reynolds-averaged Navier-Stokes equations. We found that the power limit increases linearly with the side force, and it should be exerted from the upstream side edges of the array. We conclude that future arrays might not be made only of turbines that harvest power, but also of deflectors such as vertical wings of size comparable to a turbine. The promising results of this theoretical study may direct new research on the use of deflectors to maximise the power harvested by tidal arrays.

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“…The DWT considered here was designed at Clarkson University by Dr. Kenneth Visser based on his previous experimental study [47]. Figure 5 shows two views of the geometry and a photo of the real product.…”

Section: Geometrymentioning

confidence: 99%

High-Order Large-Eddy Simulations of a Wind Turbine in Ducted and Open-Rotor Configurations

Ding¹,

Zhang²,

Liang³

et al. 2022

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High-order large-eddy simulations are performed to study the performance and flow field of a ducted wind turbine operating at different tip speed ratios. To evaluate the effects of the duct, simulations with the same tip speed ratios are also performed on the corresponding open-rotor turbine. It is found that the ducted turbine consistently obtains higher power outputs than the open-rotor counterpart, and the duct itself enhances flow turbulence and blade trailing-edge vortices but weakens tip and hub vortices. Flow bifurcation is observed at the largest tip speed ratio and is identified to be caused by blade blockage effects. Comparative simulations are also performed on both turbines under different yaw angles. It is noticed that the ducted configuration is insensitive to small yaw angles and maintains higher power outputs than the open-rotor configuration at all yaw angles. Moreover, it is observed that the wakes of both configurations recover more quickly as the yaw angle increases.

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Experimental validation of a ducted wind turbine design strategy

Cited by 29 publications

References 21 publications

Maximal power per device area of a ducted turbine

Maximal power per device area of a ducted turbine

Use of streamnormal forces within an array of tidal power harvesters

High-Order Large-Eddy Simulations of a Wind Turbine in Ducted and Open-Rotor Configurations

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