scholarly journals Reconstruction of Three-Dimensional Dynamic Wind-Turbine Wake Wind Fields with Volumetric Long-Range Wind Doppler LiDAR Measurements

2019 ◽  
Vol 11 (22) ◽  
pp. 2665 ◽  
Author(s):  
Beck ◽  
Kühn
Keyword(s):  
Wind Turbine ◽  
Long Range ◽  
Wind Field ◽  
Three Dimensional ◽  
Wake Flow ◽  
Wind Fields ◽  
Wake Field ◽  
Eddy Simulation ◽  
Lidar Measurements ◽  
Set Up

This paper presents a method for reconstructing the wake wind field of a wind turbine based on planar light detection and ranging (LiDAR) scans crossing the wake transversally in the vertical and horizontal directions. Volumetric measurements enable the study of wake characteristics in these two directions. Due to a lack of highly resolved wind speed measurements as reference data, we evaluate the reconstruction in a synthetic environment and determine the reconstruction errors. The wake flow of a multi-megawatt wind turbine is calculated within a 10-min large-eddy simulation (LES) for high-thrust loading conditions. We apply a numerical LiDAR simulator to this wake wind field to achieve realistic one-dimensional velocity data. We perform a nacelle-based set-up with combined plan position indicator and range height indicator scans with eight scanning velocities each. We temporally up-sample the synthetic LiDAR data with a weighted combination of forward- and backward-oriented space–time conversion to retrospectively extract high-resolution wake characteristic dynamics. These dynamics are used to create a dynamic volumetric wake deficit. Finally, we reconstruct the dynamic wake wind field in three spatial dimensions by superposing an ambient wind field with the dynamic volumetric wake deficit. These results demonstrate the feasibility of wake field reconstruction using long-range LiDAR measurements.

scholarly journals Lidar measurements of yawed-wind-turbine wakes: characterization and validation of analytical models

2020 ◽  
Vol 5 (4) ◽  
pp. 1253-1272
Author(s):  
Peter Brugger ◽  
Mithu Debnath ◽  
Andrew Scholbrock ◽  
Paul Fleming ◽  
Patrick Moriarty ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Cross Sections ◽  
Wake Flow ◽  
Analytical Models ◽  
Power Coefficient ◽  
Doppler Lidar ◽  
Scada System ◽  
Lidar Measurements ◽  
Set Up ◽  
Yaw Angle

Abstract. Wake measurements of a scanning Doppler lidar mounted on the nacelle of a full-scale wind turbine during a wake-steering experiment were used for the characterization of the wake flow, the evaluation of the wake-steering set-up, and the validation of analytical wake models. Inflow-scanning Doppler lidars, a meteorological mast, and the supervisory control and data acquisition (SCADA) system of the wind turbine complemented the set-up. Results from the wake-scanning Doppler lidar showed an increase in the wake deflection with the yaw angle and that the wake deflection was not in all cases beneficial for the power output of a downstream turbine due to a bias of the inflow wind direction perceived by the yawed wind turbine and the wake-steering design implemented. Both observations could be reproduced with an analytical model that was initialized with the inflow measurements. Error propagation from the inflow measurements that were used as model input and the power coefficient of a waked wind turbine contributed significantly to the model uncertainty. Lastly, the span-wise cross section of the wake was strongly affected by wind veer, masking the effects of the yawed wind turbine on the wake cross sections.

scholarly journals Long-range WindScanner System

2016 ◽  
Author(s):  
Nikola Vasiljevic ◽  
Guillaume Lea ◽  
Michael Courtney ◽  
Jean-Pierre Cariou ◽  
Jakob Mann ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Long Range ◽  
Wind Field ◽  
Wind Farms ◽  
Laser Beams ◽  
Wind Fields ◽  
High Quality ◽  
Technical Aspects ◽  
Points Of Interest ◽  
Field Campaigns

In this paper, the technical aspects of a multi-lidar instrument, the long-range WindScanner system, will be presented accompanied by an overview of the results from several field campaigns. The long-range WindScanner system consists of three spatially separated coherent Doppler scanning lidars and a remote master computer that coordinates them. The lidars were carefully engineered to perform arbitrary and time controlled scanning trajectories. Their wireless coordination via the master computer allows achieving and maintaining lidars’ synchronization within ten milliseconds. As a whole, the long-range WindScanner system can measure an entire wind field by emitting and directing three laser beams to intersect, and then by moving the beam intersection over the points of interest. The long-range WindScanner system was developed to tackle the need for high-quality observations of wind fields from scales of modern wind turbine and wind farms. It has been in operation since 2013.

scholarly journals Lidar measurements of yawed wind turbine wakes: characterisation and validation of analytical models

2020 ◽  
Author(s):  
Peter Brugger ◽  
Mithu Debnath ◽  
Andrew Scholbrock ◽  
Paul Fleming ◽  
Patrick Moriarty ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Cross Sections ◽  
Wake Flow ◽  
Analytical Models ◽  
Power Coefficient ◽  
Doppler Lidar ◽  
Wind Turbine Control ◽  
Lidar Measurements ◽  
Set Up ◽  
Yaw Angle

Abstract. Wake measurements of a scanning Doppler lidar mounted on the nacelle of a yawed full-scale wind turbine are used for the characterization of the wake flow and the validation of analytical wake models. Inflow scanning Doppler lidars, a meteorological mast and the data of the wind turbine control system complemented the set-up. Results showed an increase of the wake deflection with the yaw angle that agreed with two of the three compared models. For yawed cases, the predicted power of a waked downwind turbine estimated by the two previously successful models had an error of 17 % and 24 % compared to the SCADA data and 12 % and 13 % compared to the power estimated from the Doppler lidar measurements. Shortcomings of the method to compute the power coefficient in an inhomogeneous wind field are likely the reason for disagreement between estimates using the Doppler lidar data versus SCADA data. Further, it was found that some wake steering cases were detrimental to the power output due to errors of the inflow wind direction perceived by the yawed wind turbine and the wake steering design implemented. Lastly, it was observed that the spanwise cross-section of the wake is strongly affected by wind veer, masking the kidney-shaped wake cross-sections observed from wind-tunnel experiments and numerical simulations.

Numerical Simulation for Wind Turbine Wake and Effects From Different Atmospheric Boundary Conditions

2016 ◽  
Author(s):  
Peng Zhou ◽  
Xiuling Wang
Keyword(s):  
Boundary Conditions ◽  
Wind Turbine ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Wake Flow ◽  
Dynamics Simulation ◽  
Experiment Data ◽  
Eddy Simulation ◽  
Turbine Wake ◽  
Wind Turbine Wake

This research focuses on the computational fluid dynamics simulation of near wind turbine wake. Three dimensional wind turbine model is built based on S809 airfoil data [1]. Three different turbulence models are used and compared. They are Realizable k-ε model, SST k-ω model, and Large Eddy Simulation (LES) model. The simulation results from different turbulence models are compared with the NREL Phase VI experiment data. Different boundary conditions, including neutral and unstable conditions, were adopted in the simulation to analyze their influence on wake flow. Updraft and downdraft are considered in this part. Overall numerical results match well with the experiment data. The discussion also compares wind turbine wake under different atmospheric boundary conditions.

scholarly journals Wind turbine load validation in wakes using wind field reconstruction techniques and nacelle lidar wind retrievals

2021 ◽  
Vol 6 (3) ◽  
pp. 841-866
Author(s):  
Davide Conti ◽  
Vasilis Pettas ◽  
Nikolay Dimitrov ◽  
Alfredo Peña
Keyword(s):  
Time Series ◽  
Wind Turbine ◽  
Wind Field ◽  
Wake Flow ◽  
Tensor Model ◽  
Statistical Uncertainty ◽  
Gaussian Shape ◽  
Field Reconstruction ◽  
Wake Field ◽  
Wake Fields

Abstract. This study proposes two methodologies for improving the accuracy of wind turbine load assessment under wake conditions by combining nacelle-mounted lidar measurements with wake wind field reconstruction techniques. The first approach consists of incorporating wind measurements of the wake flow field, obtained from nacelle lidars, into random, homogeneous Gaussian turbulence fields generated using the Mann spectral tensor model. The second approach imposes wake deficit time series, which are derived by fitting a bivariate Gaussian shape function to lidar observations of the wake field, on the Mann turbulence fields. The two approaches are numerically evaluated using a virtual lidar simulator, which scans the wake flow fields generated with the dynamic wake meandering (DWM) model, i.e., the target fields. The lidar-reconstructed wake fields are then input into aeroelastic simulations of the DTU 10 MW wind turbine for carrying out the load validation analysis. The power and load time series, predicted with lidar-reconstructed fields, exhibit a high correlation with the corresponding target simulations, thus reducing the statistical uncertainty (realization-to-realization) inherent to engineering wake models such as the DWM model. We quantify a reduction in power and loads' statistical uncertainty by a factor of between 1.2 and 5, depending on the wind turbine component, when using lidar-reconstructed fields compared to the DWM model results. Finally, we show that the number of lidar-scanned points in the inflow and the size of the lidar probe volume are critical aspects for the accuracy of the reconstructed wake fields, power, and load predictions.

scholarly journals Large-Eddy Simulation of Wind Turbine Flows: A New Evaluation of Actuator Disk Models

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3745
Author(s):  
Tristan Revaz ◽  
Fernando Porté-Agel
Keyword(s):  
Boundary Layer ◽  
Simple Model ◽  
Wind Turbine ◽  
Wake Flow ◽  
Test Case ◽  
Flow Solver ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Layer Flow ◽  
Advanced Model

Large-eddy simulation (LES) with actuator models has become the state-of-the-art numerical tool to study the complex interaction between the atmospheric boundary layer (ABL) and wind turbines. In this paper, a new evaluation of actuator disk models (ADMs) for LES of wind turbine flows is presented. Several details of the implementation of such models are evaluated based on a test case studied experimentally. In contrast to other test cases used in previous similar studies, the present test case consists of a wind turbine immersed in a realistic turbulent boundary-layer flow, for which accurate data for the turbine, the flow, the thrust and the power are available. It is found that the projection of the forces generated by the turbine into the flow solver grid is crucial for rotor predictions, especially for the power, and less important for the wake flow prediction. In this context, the projection of the forces into the flow solver grid should be as accurate as possible, in order to conserve the consistency between the computed axial velocity and the projected axial force. Also, the projection of the force is found to be much more important in the rotor plane directions than in the streamwise direction. It is found that for the case of a wind turbine immersed in a realistic turbulent boundary-layer flow, the potential spurious numerical oscillations originating from sharp force projections are not harmful to the results. By comparing an advanced model which computes the non-uniform distribution of the turbine forces over the rotor with a simple model which assumes uniform effects of the turbine forces, it is found that both can lead to accurate results for the far wake flow and the thrust and power predictions. However, the comparison shows that the advanced model leads to better results for the near wake flow. In addition, it is found that the simple model overestimates the rotor velocity prediction in comparison to the advanced model. These elements are explained by the lack of local feedback between the axial velocity and the axial force in the simple model. By comparing simulations with and without including the effects of the nacelle and tower, it is found that the consideration of the nacelle and tower is relatively important both for the near wake and the power prediction, due to the shadow effects. The grid resolution is not found to be critical once a reasonable resolution is used, i.e. in the order of 10 grid points along each direction across the rotor. The comparison with the experimental data shows that an accurate prediction of the flow, thrust, and power is possible with a very reasonable computational cost. Overall, the results give important guidelines for the implementation of ADMs for LES.

scholarly journals Engineering Comprehensive Model of Complex Wind Fields for Flight Simulation

Aerospace ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 145
Author(s):  
Jianwei Chen ◽  
Liangming Wang ◽  
Jian Fu ◽  
Zhiwei Yang
Keyword(s):  
Wind Field ◽  
Three Dimensional ◽  
Great Influence ◽  
Spatial Location ◽  
Flight Simulation ◽  
Comprehensive Model ◽  
Flight Trajectory ◽  
Wind Fields ◽  
Wind Field Simulation ◽  
Low Level Jet

A complex wind field refers to the typical atmospheric disturbance phenomena existing in nature that have a great influence on the flight of aircrafts. Aimed at the issues involving large volume of data, complex computations and a single model in the current wind field simulation approaches for flight environments, based on the essential principles of fluid mechanics, in this paper, wind field models for two kinds of wind shear such as micro-downburst and low-level jet plus three-dimensional atmospheric turbulence are established. The validity of the models is verified by comparing the simulation results from existing wind field models and the measured data. Based on the principle of vector superposition, three wind field models are combined in the ground coordinate system, and a comprehensive model of complex wind fields is established with spatial location as the input and wind velocity as the output. The model is applied to the simulated flight of a rocket projectile, and the change in the rocket projectile’s flight attitude and flight trajectory under different wind fields is analyzed. The results indicate that the comprehensive model established herein can reasonably and efficiently reflect the influence of various complex wind field environments on the flight process of aircrafts, and that the model is simple, extensible, and convenient to use.

scholarly journals Real-time three dimensional wind field reconstruction from nacelle LiDAR measurements

2018 ◽  
Vol 1037 ◽  
pp. 032037
Author(s):  
F. Guillemin ◽  
H.-N. Nguyen ◽  
G. Sabiron ◽  
D. Di Domenico ◽  
M. Boquet
Keyword(s):  
Real Time ◽  
Wind Field ◽  
Three Dimensional ◽  
Field Reconstruction ◽  
Lidar Measurements

scholarly journals On the aerodynamic flow around a cyclist model at the hoods position

2019 ◽  
Vol 23 (1) ◽  
pp. 35-47 ◽  
Author(s):  
Jiun-Jih Miau ◽  
Shang-Ru Li ◽  
Zong-Xiu Tsai ◽  
Mai Van Phung ◽  
San-Yi Lin
Keyword(s):  
Wind Tunnel ◽  
Water Channel ◽  
Three Dimensional ◽  
Simulation Method ◽  
Reynolds Numbers ◽  
Numerical Results ◽  
Wake Flow ◽  
Model Surface ◽  
Eddy Simulation ◽  
Separation Pattern

Abstract Aerodynamic flow around an 1/5 scale cyclist model was studied experimentally and numerically. First, measurements of drag force were performed for the model in a low-speed wind tunnel at Reynolds numbers from $$5.5 \times 10^{4}$$5.5×104 to $$1.8 \times 10^{5}$$1.8×105. Meanwhile, numerical computation using a large eddy simulation method was performed at three Reynolds numbers of $$1.1 \times 10^{4}$$1.1×104, $$6.5 \times 10^{4}$$6.5×104 and $$1.5 \times 10^{5}$$1.5×105 to obtain the drag coefficients for comparison. Second, flow visualization was made in a water channel and the wind tunnel mentioned to examine the three-dimensional flow separation pattern on the model surface, which could also be realized from the numerical results. Finally, a wake flow survey based on the hot-wire measurements in the wind tunnel showed that in the near-wake region, the flow was featured with the formation of multiple streamwise vortices. The numerical results further indicated that these vortices were evolved from the separated flows occurred on the model surface. Graphic Abstract

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