Instantaneous Response and Mutual Interaction between Wind Turbine and Flow

Andersen, Søren Juhl; Sørensen, Jens Nørkær

doi:10.1088/1742-6596/1037/7/072011

Cited by 5 publications

(5 citation statements)

References 19 publications

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“…Conversely, large C T has a large impact on the flow development and therefore the maximum cross-correlation is significant reduced. This corresponds to previous results [28,29] where the cross-correlations are broken by the presence of the turbine. Second, the longest length scales typically have higher maximum cross-correlation, except at large downstream distances for high T SR, where the increased turbulence levels further break coherent structures of the inflow.…”

Section: Resultssupporting

confidence: 91%

Dynamic interaction of inflow and rotor time scales and impact on single turbine wake recovery

Andersen,

Hodgson,

Aa Madsen

2024

J. Phys.: Conf. Ser.

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The entrainment and recovery of wind turbine wakes are highly dependent on atmospheric inflow conditions, which has typically been quantified through the turbulent intensity. However, recent studies have shown that the integral time scales of the inflow has significant impact on the wake recovery. Concurrently, increased power production can also be achieved through intentionally introducing beneficial time scales by altering the control of the individual wind turbines. This study studies the combined impact of the dynamic interaction between dominant inflow and rotor time scales. The results show increased power production of a downstream wind turbine of more than 50% for the largest thrust coefficients and tip-speed ratios (TSR). However, the peak power gain occurs at different downstream positions indicating that combinations of inflow time scales and TSR = 6 result in faster near wake breakdown compared to the same inflow time scales combined with higher thrust coefficient of TSR = 8.

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Section: Resultssupporting

confidence: 91%

Dynamic interaction of inflow and rotor time scales and impact on single turbine wake recovery

Andersen,

Hodgson,

Aa Madsen

2024

J. Phys.: Conf. Ser.

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“…By using dynamic mode decomposition, which is related to the POD technique, Iungo et al (2015a) constructed a reduced-order model of the wind-turbine wakes embedded in a Kalman filter, and demonstrated the potential of this tool for real-time flow control in large-scale wind farms. Andersen and Sørensen (2018) found that the correlation between the instantaneous turbine performance and the upstream wake position is limited in very large wind farms, which they argue limits the benefits of wake steering as a control strategy, and point out that these results should be extended to cases in which intentional yaw misalignment is considered. In addition, they argued that the potential of induction-based control strategies should be further investigated.…”

Section: Introductionmentioning

confidence: 97%

Characterizing the Coherent Structures Within and Above Large Wind Farms

Zhang

Stevens

2019

Boundary-Layer Meteorol

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We study large-eddy simulations of coherent structures within and above different windfarm configurations in a neutral atmospheric boundary layer (ABL) using proper orthogonal decomposition (POD) to improve understanding of the flow structures in both physical and spectral space. We find that the spanwise extent of elongated streamwise counter-rotating rolls is constrained by the spanwise turbine spacings. The very large streamwise extent of the observed POD flow structures in physical space indicates that the interaction between the wind turbines and the ABL also causes large-scale flow organization. Using a spectral POD analysis to characterize the coherent structures at a certain frequency, we find that the flow dynamics for the frequency corresponding to the time a fluid parcel takes to traverse one streamwise turbine spacing is dominated by the wind-turbine wakes. The first POD mode at this frequency indicates that the wakes are spatially correlated. However, the flow dynamics at lower frequencies, corresponding to the longer time a fluid parcel takes to traverse the entire wind farm, are dominated by large flow structures originating from the ABL dynamics. We find that hundreds of POD modes are required to accurately describe the full three-dimensional flow profiles in large wind farms, while even more POD modes are required to accurately describe the Reynolds stresses that are important to describe the momentum exchange between the wind farm and the ABL. This indicates that wind-farm dynamics in the ABL are very complex.

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“…Particularly for large turbines, modelling flexible deformation resulted in noticeable differences in blade loading, damage equivalent loads and power production for the AL, which were not seen for a standalone BEM tool, due to the ability of the blades to interact with the flow. Andersen and Sørensen (2018) studies correlations between inflow, turbine operation and wake flow, and demonstrates the importance of both having detailed knowledge of turbine inflow, and modelling the mutual turbine and flow interaction. In a comparison between fully resolved FSI simulations, measurement data and an aeroelastic blade element momentum (BEM) tool, Grinderslev et al (2021) likewise showed discrepancies between CFD-based FSI and BEM-based simulations in predicting blade loading due to complex inflow, indicating the importance of using higher-fidelity methods.…”

Section: Introductionmentioning

confidence: 99%

Validation of Aeroelastic Actuator Line for Wind Turbine Modelling in Complex Flows

et al. 2022

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The actuator line method is a widely used technique to model wind turbines in computational fluid dynamics, as it significantly reduces the required computational expense in comparison to simulations using geometrically resolved blades. Actuator line coupled to an aeroelastic solver enables not only the study of detailed wake dynamics but also aeroelastic loads, flexible blade deformation and how this interacts with the flow. Validating aeroelastic actuator line predictions of blade loading, deflection and turbine wakes in complex inflow scenarios is particularly relevant for modern turbine designs and wind farm studies involving realistic inflows, wind shear or yaw misalignment. This work first implements a vortex-based smearing correction in an aeroelastic coupled actuator line, and performs a grid resolution and smearing parameter study which demonstrates significant improvement in the blade loading and in the numerical dependencies of predicted thrust and power output. A validation is then performed using a 2.3 MW turbine with R = 40 m radius, comparing against blade resolved fluid-structure interaction simulations and full-scale measurement data, in both laminar and turbulent inflows including both high shear and high yaw misalignment. For an axisymmetric laminar inflow case, the agreement between blade resolved and actuator line simulations is excellent, with prediction of integrated quantities within 0.2%. In more complex flow cases, good agreement is seen in overall trends but the actuator line predicts lower blade loading and flapwise deflection, leading to underpredictions of thrust by between 5.3% and 8.4%. The discrepancies seen can be attributed to differences in wake flow, induction, the reliance of the actuator line on the provided airfoil data and the force application into the computational domain. Comparing the wake between coupled actuator line and blade resolved simulations for turbulent flow cases also shows good agreement in wake deficit and redirection, even under high yaw conditions. Overall, this work validates the implementation of the vortex-based smearing correction and demonstrates the ability of the actuator line to closely match blade loading and deflection predictions of blade resolved simulations in complex flows, at a significantly lower computational cost.

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Instantaneous Response and Mutual Interaction between Wind Turbine and Flow

Cited by 5 publications

References 19 publications

Dynamic interaction of inflow and rotor time scales and impact on single turbine wake recovery

Dynamic interaction of inflow and rotor time scales and impact on single turbine wake recovery

Characterizing the Coherent Structures Within and Above Large Wind Farms

Validation of Aeroelastic Actuator Line for Wind Turbine Modelling in Complex Flows

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