Influence of the Coriolis force on the structure and evolution of wind turbine wakes

Abkar, Mahdi; Porté‐Agel, Fernando

doi:10.1103/physrevfluids.1.063701

Cited by 51 publications

(53 citation statements)

References 77 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…11. A similar result has been observed in field measurements (Magnusson and Smedman, 1994) and LES of a single wind turbine and wind farms in a stable ABL (Lu and Porté-Agel, 2011;Churchfield et al, 2016;Abkar and Porté-Agel, 2016). The single-AD test case confirms that the Coriolis force indirectly deflects a wind turbine or farm wake clockwise because of the wind veer.…”

Section: Single-wake Simulation In a Shallow Ablsupporting

confidence: 72%

“…Here, we define the wake deflection as clockwise and anticlockwise, as observed from above, and for simplicity we only discuss wind farms located in the Northern Hemisphere. More recently, Churchfield et al (2016) and Abkar and Porté-Agel (2016) have shown similar results using LES of wakes in a stable ABL. By contrast, Dörenkämper et al (2015) reported a small anticlockwise deflection in a LES of a wind farm wake in a stable ABL.…”

Section: Introductionsupporting

confidence: 56%

“…Secondly, the two wind farm simulations are repeated using a Coriolis force that is set as constant in horizontal directions in order to remove the influence of local changes in the Coriolis force in the wake region and to isolate the effect of the present wind veer on the wind farm wake deflection. In addition, we investigate the wake deflection of a single AD placed in a shallow ABL, where the wind veer over the rotor area is large, to see if our RANS model agrees with LES results from Lu and Porté-Agel (2011), Churchfield et al (2016), Abkar and Porté-Agel (2016), and field measurements of Magnusson and Smedman (1994). Note that this work is an extension of van der Laan and Sørensen (2016), presented at the TORQUE 2016 conference.…”

Section: Introductionmentioning

confidence: 99%

“…The present wind veer deflects the wind farm wake clockwise (Magnusson and Smedman, 1994;Lu and Porté-Agel, 2011;Churchfield et al, 2016;Abkar and Porté-Agel, 2016). …”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Why the Coriolis force turns a wind farm wake clockwise in the Northern Hemisphere

Laan

Sørensen²

2017

Wind Energ. Sci.

View full text Add to dashboard Cite

Abstract.The interaction between the Coriolis force and a wind farm wake is investigated by Reynoldsaveraged Navier-Stokes simulations, using two different wind farm representations: a high roughness and 5 × 5 actuator disks. Surprisingly, the calculated wind farm wake deflection is the opposite in the two simulations. A momentum balance in the cross flow direction shows that the interaction between the Coriolis force and the 5 × 5 actuator disks is complex due to turbulent mixing of veered momentum from above into the wind farm, which is not observed for the interaction between the Coriolis force and a roughness change. When the wind farm simulations are performed with a horizontally constant Coriolis force in order to isolate the effect of the wind veer, the wind farm wake deflection of the 5 × 5 actuator disks simulation remains unchanged. This proves that the present wind veer deflects the wind farm wake and not the local changes in the Coriolis force in the wake deficit region. An additional simulation of a single actuator disk, operating in a shallow atmospheric boundary layer, confirms that the Coriolis force indirectly turns a wind turbine wake clockwise, as observed from above, due to the presence of a strong wind veer.

show abstract

Section: Single-wake Simulation In a Shallow Ablsupporting

confidence: 72%

Section: Introductionsupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

“…The present wind veer deflects the wind farm wake clockwise (Magnusson and Smedman, 1994;Lu and Porté-Agel, 2011;Churchfield et al, 2016;Abkar and Porté-Agel, 2016). …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Why the Coriolis force turns a wind farm wake clockwise in the Northern Hemisphere

Laan

Sørensen²

2017

Wind Energ. Sci.

View full text Add to dashboard Cite

show abstract

“…Much work, including numerical simulations and field-scale measurements [1][2][3][4][5][6][7][8][9], has been done recently to unravel the impact of lateral wind shear (also known as vertical wind veer) on the aerodynamics of wind turbine wakes. All these studies highlighted that, for the large utility-scale wind turbines, the impact of the lateral wind shear cannot be ignored.…”

Section: Introductionmentioning

confidence: 99%

An Analytical Model for the Effect of Vertical Wind Veer on Wind Turbine Wakes

2018

Self Cite

View full text Add to dashboard Cite

Abstract:In this study, an analytical wake model for predicting the mean velocity field downstream of a wind turbine under veering incoming wind is systematically derived and validated. The new model, which is an extended version of the one introduced by Bastankhah and Porté-Agel, is based upon the application of mass conservation and momentum theorem and considering a skewed Gaussian distribution for the wake velocity deficit. Particularly, using a skewed (instead of axisymmetric) Gaussian shape allows accounting for the lateral shear in the incoming wind induced by the Coriolis force. This analytical wake model requires only the wake expansion rate as an input parameter to predict the mean wake flow downstream. The performance of the proposed model is assessed using the large-eddy simulation (LES) data of a full-scale wind turbine wake under the stably stratified condition. The results show that the proposed model is capable of predicting the skewed structure of the wake downwind of the turbine, and its prediction for the wake velocity deficit is in good agreement with the high-fidelity simulation data.

show abstract

Field investigation on the influence of yaw misalignment on the propagation of wind turbine wakes

et al. 2018

View full text Add to dashboard Cite

A comprehensive understanding of the wake development of wind turbines is essential for improving the power yield of wind farms and for reducing the structural loading of the turbines.Reducing the overall negative impact of wake flows on individual turbines in a farm is one goal of wind farm control. We aim to demonstrate the applicability of yaw control for deflecting wind turbine wakes in a full-scale field experiment. For this purpose, we conducted a measurement campaign at a multimegawatt onshore wind turbine including inflow and wake flow measurements using ground-and nacelle-based long-range light detection and ranging devices. Yaw misalignments of the turbine with respect to the inflow direction of up to 20 • were investigated. We were able to show that under neutral atmospheric conditions, these turbine misalignments cause lateral deflections of its wake. Larger yaw misalignments resulted in greater wake deflection.Because of the inherent struggle in capturing complex and highly dynamic ambient conditions in the field using a limited number of sensors, we particularly focused on providing a comprehensive and comprehensible description of the measurement setup, including the identification of potential uncertainties. KEYWORDSatmospheric boundary layer, atmospheric inflow, lidar, wake deflection, wind farm control INTRODUCTIONWind turbines in a wind farm are typically subjected to mutual aerodynamic interactions due to their wakes. Depending on the farm layout and inflow direction, this can lead to unfavourable structural loading and a substantial reduction in the power yield over extended periods of time . 1-3 Reducing the overall negative impact of wake flows on individual turbines in a farm is one goal of wind farm control. However, a successful implementation of control mechanisms requires a broad understanding of the flow development for various ambient conditions and the interaction between turbines and the flow.One specific approach that has proven its potential in simulations and wind tunnel experiments is wake deflection through turbine operation under yaw misalignment. In this case, an offset between the inflow direction and the orientation of a turbine is deliberately introduced to alter its wake trajectory. Hereinafter, we refer to this method as yaw control for the sake of simplicity. It aims to generate more favourable inflow conditions for downstream turbines by reducing the wake effects. This can, for example, be used to maximize the power output of a wind farm, to mitigate power fluctuation or to reduce turbine loads. With respect to power maximization, it should be considered that misaligned wind turbines generate less power. Therefore, it must be ensured that the power increase generated by the downstream turbines is sufficient for improving the overall power yield of the wind farm.The concept of wake deflection has already been successfully applied in wind tunnel experiments by Clayton and Filby in 1982. 4 Further investigations of the power yield and characteristics of the downstream d...

show abstract

Influence of the Coriolis force on the structure and evolution of wind turbine wakes

Cited by 51 publications

References 77 publications

Why the Coriolis force turns a wind farm wake clockwise in the Northern Hemisphere

Why the Coriolis force turns a wind farm wake clockwise in the Northern Hemisphere

An Analytical Model for the Effect of Vertical Wind Veer on Wind Turbine Wakes

Field investigation on the influence of yaw misalignment on the propagation of wind turbine wakes

Contact Info

Product

Resources

About