Effect of tower and nacelle on the flow past a wind turbine

Santoni, Christian; Carrasquillo, Kenneth; Arenas-Navarro, Isnardo; Leonardi, Stefano

doi:10.1002/we.2130

Cited by 105 publications

(89 citation statements)

References 25 publications

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“…The turbine tower and nacelle are directly simulated using the immersed boundary method . UTD‐WF has been previously validated against measurements from wind tunnel experiments on model wind turbines …”

Section: Methodsmentioning

confidence: 99%

Effect of the turbine scale on yaw control

2018

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Yaw misalignment between the incoming wind and the rotor of a turbine causes a lateral displacement of the wake. This effect can be exploited to avoid or mitigate wake interactions in wind farms, so that power losses are minimized. We performed large‐eddy simulations to evaluate yaw control for a three‐turbine wind farm. We used two different turbine models to assess how the size of the turbine rotor affects the farm efficiency and the effectiveness of the control strategy. A utility‐scale wind turbine with rotor diameter of 126 m is compared with a scaled research wind turbine with rotor diameter of 27 m. In both cases, a model‐free algorithm is used to determine the turbine yaw set point, which maximizes total power production. The algorithm is the nested extremum‐seeking control (NESC), which allows for the coordinated optimization of the wind turbine operating points. The results achieved with NESC are validated by computing a static performance map for different yaw angles. NESC converges to optimal operating conditions, which are in good agreement with the static map benchmark. Numerical results show that a larger rotor diameter induces larger wake deflection, thus achieving higher power improvements. From the analysis of the turbine structural loads, an increase in damage equivalent load is observed for both the yawed turbine and the waked one. Present results suggest that there is a cost‐effective trade‐off between performance and loads for large turbines.

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Section: Methodsmentioning

confidence: 99%

Effect of the turbine scale on yaw control

2018

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“…The entrainment of mean kinetic energy into the wake is enhanced after the tip vortex breakdown [50]. Thus, the wake recovery is faster for the non-uniform grid case than the "clean" inlet case ( Figure 6).…”

Section: Wake Structuresmentioning

confidence: 97%

“…A large turbulent intensity is also found in the core of the near wake, due to the presence of tower and nacelle. The wake of the tower and nacelle is tilted laterally because of the swirl imparted by the rotor to the flow [50]. Proceeding downstream, the wake of the tower is advected towards the edge of the rotor.…”

Section: Turbulent Kinetic Energymentioning

confidence: 99%

Large-Eddy Simulations of Two In-Line Turbines in a Wind Tunnel with Different Inflow Conditions

Ciri

Petrolo²,

Salvetti³

et al. 2017

Energies

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Numerical simulations reproducing a wind tunnel experiment on two in-line wind turbines have been performed. The flow features and the array performances have been evaluated in different inflow conditions. Following the experimental setup, different inlet conditions are obtained by simulating two grids upstream of the array. The increased turbulence intensity due to the grids improves the wake recovery and the efficiency of the second turbine. However, the inlet grid induces off-design operation on the first turbine, decreasing the efficiency and increasing fatigue loads. Typical grid flow patterns are observed past the rotor of the first turbine, up to the near wake. Further downstream, the signature of the grid on the flow is quite limited. An assessment of numerical modeling aspects (subgrid scale tensor and rotor parameterization) has been performed by comparison with the experimental measurements.

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“…Preliminary RANS simulations have been performed by using as inlet the average velocity, U eq , measured at x/D=3.25, which is a downstream location where the pressure can be considered practically recovered to ambient pressure and the turbulent fluxes being the major component in the momentum equation [6,7].…”

Section: Estimate Of Axial Induction By Coupling Lidar Data and Rans mentioning

confidence: 99%

“…Numerical simulations of wind turbine wakes are typically performed by means of actuator line or disk models [1][2][3][4][5][6][7], which rely on tabulated data of the blade geometry and aerodynamic coefficients for the various airfoils composing the blades. These parameters, coupled with the evaluation of the relative wind speed along the turbine blades, allow predicting the rotor aerodynamic forces.…”

Section: Introductionmentioning

confidence: 99%

Quantification of the axial induction exerted by utility-scale wind turbines by coupling LiDAR measurements and RANS simulations

Iungo

Letizia

Zhan

2018

J. Phys.: Conf. Ser.

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Abstract. The axial induction exerted by utility-scale wind turbines for different operative and atmospheric conditions is estimated by coupling ground-based LiDAR measurements and RANS simulations. The LiDAR data are thoroughly post-processed in order to average the wake velocity fields by using as common reference frame their respective wake directions and the turbine hub location. The various LiDAR scans are clustered according to their incoming wind speed at hub height and atmospheric stability regime, namely Bulk Richardson number. Time-averaged velocity fields are then calculated as ensemble averages of the scans belonging to the same cluster. The LiDAR measurements are coupled with RANS simulations in order to estimate the rotor axial induction for each cluster of the LiDAR data. First, a control volume analysis of the streamwise momentum is applied to the time-averaged LiDAR velocity fields to obtain an initial estimate of the axial induction over the rotor disk. The calculated thrust force is imposed as forcing of an axisymmetric RANS simulation in order to estimate pressure, radial velocity and momentum fluxes. The latter are combined with the LiDAR streamwise velocity field in order to refine the estimate of the rotor axial induction through the control volume approach. This process is repeated iteratively until achieving convergence on the rotor axial induction while minimizing difference between LiDAR and RANS streamwise velocity fields. This procedure allows to single out the reduction in thrust load while the blade pitch angle is increased transitioning from region 2 to 3 of the power curve. Furthermore, an enhanced thrust force is observed for a fixed incoming wind speed and transitioning from stable to convective stability regimes. The presented technique is proposed as a data-driven alternative to the blade element momentum theory typically used with current actuator disk models in order to quantify rotor aerodynamic thrust for different operative and atmospheric conditions.

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Effect of tower and nacelle on the flow past a wind turbine

Cited by 105 publications

References 25 publications

Effect of the turbine scale on yaw control

Effect of the turbine scale on yaw control

Large-Eddy Simulations of Two In-Line Turbines in a Wind Tunnel with Different Inflow Conditions

Quantification of the axial induction exerted by utility-scale wind turbines by coupling LiDAR measurements and RANS simulations

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