scholarly journals Wind Farm Fault Detection by Monitoring Wind Speed in the Wake Region

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6559
Author(s):  
Minh-Quang Tran ◽  
Yi-Chen Li ◽  
Chen-Yang Lan ◽  
Meng-Kun Liu
Keyword(s):  
Energy Dissipation ◽  
Wind Speed ◽  
Fault Detection ◽  
Wind Turbine ◽  
Wind Farm ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Wake Region ◽  
Navier Stokes Equations ◽  
Dissipation Model

A novel concept of wind farm fault detection by monitoring the wind speed in the wake region is proposed in this study. A wind energy dissipation model was coupled with a computational fluid dynamics solver to simulate the fluid field of a wind turbine array, and the wind velocity and direction in the simulation were exported for identifying wind turbine faults. The 3D steady Navier–Stokes equations were solved by using the cell center finite volume method with a second order upwind scheme and a k−ε turbulence model. In addition, the wind energy dissipation model, derived from energy balance and Betz’s law, was added to the Navier–Stokes equations’ source term. The simulation results indicate that the wind speed distribution in the wake region contains significant information regarding multiple wind turbine faults. A feature selection algorithm specifically designed for the analysis of wind flow was proposed to reduce the number of features. This algorithm proved to have better performance than fuzzy entropy measures and recursive feature elimination methods under a limited number of features. As a result, faults in the wind turbine array could be detected and identified by machine learning algorithms.

A Viscous Three-Dimensional Differential/Actuator-Disk Method for the Aerodynamic Analysis of Wind Farms

2002 ◽  
Vol 124 (4) ◽  
pp. 345-356 ◽  
Author(s):  
Idriss Ammara ◽  
Christophe Leclerc ◽  
Christian Masson
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Stokes Equations ◽  
Control Volume ◽  
Three Dimensional ◽  
Wind Farms ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Promising Tool ◽  
Strip Theory

Computational Fluid Dynamics (CFD) is a promising tool for the analysis and optimization of wind turbine positioning inside wind parks (also known as wind farms) in order to maximize power production. In this paper, 3-D, time-averaged, steady-state, incompressible Navier-Stokes equations, in which wind turbines are represented by surficial forces, are solved using a Control-Volume Finite Element Method (CVFEM). The fundamentals of developing a practical 3-D method are discussed in this paper, with an emphasis on some of the challenges that arose during their implementation. For isolated turbines, results have indicated that the proposed 3-D method attains the same level of accuracy, in terms of performance predictions, as the previously developed 2-D axisymmetric method and the well-known momentum-strip theory. Furthermore, the capability of the proposed method to predict wind turbine wake characteristics is also illustrated. Satisfactory agreement with experimental measurements has been achieved. The analysis of a two-row periodic wind farm in neutral atmospheric boundary layers demonstrate the existence of positive interference effects (venturi effects) as well as the dominant influence of mutual interference on the performance of dense wind turbine clusters.

scholarly journals Experimental validation of wind energy estimation

2020 ◽  
Vol 24 (6 Part A) ◽  
pp. 3795-3806
Author(s):  
Predrag Zivkovic ◽  
Mladen Tomic ◽  
Vukman Bakic
Keyword(s):  
Wind Speed ◽  
Linear Model ◽  
Linear Models ◽  
Stokes Equations ◽  
Momentum Conservation ◽  
Electricity Production ◽  
Navier Stokes ◽  
Energy Estimation ◽  
Navier Stokes Equations ◽  
Non Linear

Wind power assessment in complex terrain is a very demanding task. Modeling wind conditions with standard linear models does not sufficiently reproduce wind conditions in complex terrains, especially on leeward sides of terrain slopes, primarily due to the vorticity. A more complex non-linear model, based on Reynolds averaged Navier-Stokes equations has been used. Turbulence was modeled by modified two-equations k-? model for neutral atmospheric boundary-layer conditions, written in general curvelinear non-orthogonal co-ordinate system. The full set of mass and momentum conservation equations as well as turbulence model equations are numerically solved, using the as CFD technique. A comparison of the application of linear model and non-linear model is presented. Considerable discrepancies of estimated wind speed have been obtained using linear and non-linear models. Statistics of annual electricity production vary up to 30% of the model site. Even anemometer measurements directly at a wind turbine?s site do not necessarily deliver the results needed for prediction calculations, as extrapolations of wind speed to hub height is tricky. The results of the simulation are compared by means of the turbine type, quality and quantity of the wind data and capacity factor. Finally, the comparison of the estimated results with the measured data at 10, 30, and 50 m is shown.

scholarly journals Simulations of Moving Effect of Coastal Vegetation on Tsunami Damping

2016 ◽  
Author(s):  
Ching-Piao Tsai ◽  
Ying-Chi Chen ◽  
Tri Octaviani Sihombing ◽  
Chang Lin
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Wave Height ◽  
Stokes Equations ◽  
Coastal Vegetation ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Turbulent Closure ◽  
Gmo Model

Abstract. A coupled wave-vegetation simulation is presented for the moving effect of the coastal vegetation on tsunami wave height damping. The problem is idealized by solitary wave propagating on a group of emergent cylinders. The numerical model is based on general Reynolds-averaged Navier-Stokes equations associated with renormalization group turbulent closure model by using volume of fluid technique. The general moving object (GMO) model developed in CFD code Flow-3D is applied to simulate the coupled motion of vegetation with wave dynamically. The damping of wave height and the turbulent kinetic energy dissipation as waves passed over both moving and stationary cylinders are discussed. As comparing with the stationary cylinders, it obtains markedly less wave height damping and turbulent kinetic energy dissipation by the moving cylinders. The result implies that the wave decay by the coastal vegetation might be overestimated if the mangrove vegetation was represented as stationary state.

scholarly journals The Aerodynamics of the Curled Wake: A Simplified Model in View of Flow Control

2018 ◽  
Author(s):  
Luis A. Martínez-Tossas ◽  
Jennifer Annoni ◽  
Paul A. Fleming ◽  
Matthew J. Churchfield
Keyword(s):  
Boundary Layer ◽  
Steady State ◽  
Wind Farm ◽  
Stokes Equations ◽  
Large Eddy Simulations ◽  
Simplified Model ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Actuator Disk ◽  
Large Eddy

Abstract. When a wind turbine is yawed, the shape of the wake changes and a curled wake profile is generated. The curled wake has drawn a lot of interest because of its aerodynamic complexity and applicability to wind farm controls. The main mechanism for the creation of the curled wake has been identified in the literature as a collection of vortices that are shed from the rotor plane when the turbine is yawed. This work extends that idea by using aerodynamic concepts to develop a control-oriented model for the curled wake based on approximations to the Navier-Stokes equations. The model is tested and compared to large-eddy simulations using actuator disk and line models. The model is able to capture the curling mechanism for a turbine under uniform inflow and in the case of a neutral atmospheric boundary layer. The model is then tested inside the FLOw Redirection and Induction in Steady State framework and provides excellent agreement with power predictions for cases with two and three turbines in a row.

scholarly journals Snow Particle Collection Efficiency and Adjustment Curves for the Hotplate© Precipitation Gauge

2021 ◽  
Author(s):  
Arianna Cauteruccio ◽  
Enrico Chinchella ◽  
Mattia Stagnaro ◽  
Luca G. Lanza
Keyword(s):  
Wind Speed ◽  
Bluff Body ◽  
Stokes Equations ◽  
Collection Efficiency ◽  
Navier Stokes ◽  
Strong Wind ◽  
Navier Stokes Equations ◽  
Relevant Role ◽  
Tracking Model ◽  
Precipitation Gauge

AbstractThe hotplate precipitation gauge operates by means of a thermodynamic principle. It is composed by a small size disk with two thin aluminium heated plates on the upper and lower faces. Each plate has three concentric rings to prevent the hydrometeors from sliding off in strong wind. As for the more widely used tipping-bucket and weighing gauges, measurements are affected by the wind-induced bias due to the bluff-body aerodynamics of the instrument outer shape. Unsteady Reynolds-Averaged Navier-Stokes equations were numerically solved, using a k-ω shear stress transport closure model, to simulate the aerodynamic influence of the gauge body on the airflow. Wind tunnel tests were conducted to validate simulation results. Solid particle trajectories were modelled using a Lagrangian Particle Tracking model to evaluate the influence of the airflow modification on the ability of the instrument to collect the incoming hydrometeors. A suitable parameterization of the particle size distribution, as a function of the snowfall intensity, was employed to calculate the Collection Efficiency (CE) under different wind conditions. Results reveal a relevant role of the three rings in enhancing the collection performance of the gauge. Below 7.5 m s-1, the CE curves linearly decrease with increasing the wind speed, while beyond that threshold, the blocking caused by the rings counter effects the aerodynamic induced undercatch, and the CE curves quadratically increase with the wind speed. At high wind speed, the undercatch vanishes and the instrument exhibits a rapidly increasing overcatch. For operational purposes, adjustment curves were formulated as a function of the wind speed and the measured snowfall intensity.

scholarly journals PENGARUH WINDOW TO WALL RATIO TERHADAP KENYAMANAN FISIOLOGIS DENGAN MENGGUNAKAN CFD ANSYS 14.0

2020 ◽  
Vol 3 (1) ◽  
pp. 37
Author(s):  
Rahmayanti Rahmayanti
Keyword(s):  
Wind Speed ◽  
Total Energy ◽  
Field Measurement ◽  
Air Conditioning ◽  
Natural Ventilation ◽  
Stokes Equations ◽  
Measurement Data ◽  
Field Research ◽  
Navier Stokes ◽  
Navier Stokes Equations

The use of air conditioning energy (AC) as an effort to remove heat in buildings reaches 30% of the total energy needed in the building. To reduce the use of energy in buildings by using natural ventilation because the system does not use mechanics. Field research has been carried out with the result that the openings at Balai Padang are unable to make occupants' comfort. Therefore, the existing openings will be given treatment by wider the existing openings which are 20%, 30%, and 40%. This study purpose to investigate the effect of WWR on histologic comfort. The numerical methodology is based on the solution of the Navier-Stokes equations, using K-epsilon RNG. Numerical results are validated with available field measurement data. The results obtained that by increasing the percentage of openings, the wind speed is also highPenggunaan energi air conditioning (AC) sebagai upaya penghapus panas di dalam bangunan mencapai 30% dari total energi yang dibutuhkan di dalam bangunan. Upaya yang dilakukan untuk mengurangi penggunaan energi di dalam bangunan yakni dengan menggunakan penghawaan alami sebagai penghapus panas karena sistemnya yang tidak menggunakan mekanis. Penelitian lapangan telah dilakukan dengan hasil bahwa bukaan yang ada di Balai Padang tidak mampu mencukupi kebutuhan kecepatan angin yang diperlukan untuk mendinginkan fisiologis penghuni. Oleh karena itu, bukaan yang ada akan diberikan perlakuan dengan memperbesar bukaan yang ada yakni 20%, 30% dan 40%. Penelitian ini bertujuan untuk mengetahui efek dari WWR terhadap kenyamanan fisiologis penghuni.  Metode yang digunakan adalah eksperimental dengan menggunakan bantuan software CFD (computational Fluid Dimension) berdasarkan persamaan Navier-Stoke, menggunakan K-Epsilon RNG. Eksperimen dilakukan dengan validasi hasil pengukuran lapangan. Hasil yang didapatkan bahwa dengan menambah prosentase bukaan, kecepatan angin juga semakin besar.

scholarly journals Accurate RANS Simulation of Wind Turbine Stall by Turbulence Coefficient Calibration

2018 ◽  
Vol 8 (9) ◽  
pp. 1444 ◽  
Author(s):  
Wei Zhong ◽  
Hongwei Tang ◽  
Tongguang Wang ◽  
Chengyong Zhu
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Maximum Torque ◽  
Simulation Accuracy ◽  
Navier Stokes Equations ◽  
Pressure Distributions ◽  
Sst Turbulence Model ◽  
Better Than

Stall, a complex phenomenon related to flow separation, is difficult to be predicted accurately. The motivation of the present study is to propose an approach to improve the simulation accuracy of Reynolds Averaged Navier–Stokes equations (RANS) for wind turbines in stall. The approach is implemented in three steps in simulations of the S809 airfoil and the NREL (National Renewable Energy Laboratory) Phase VI rotor. The similarity between airfoil and rotor simulations is firstly investigated. It is found that the primary reason for the inaccuracy of rotor simulation is not the rotational effect or the 3-D effect, but the turbulence-related problem that already exists in airfoil simulation. Secondly, a coefficient of the SST turbulence model is calibrated in airfoil simulation, ensuring the onset and development of the light stall are predicted accurately. The lift of the airfoil in the light stall, which was overestimated about 30%, is reduced to a level consistent with experimental data. Thirdly, the calibrated coefficient is applied to rotor simulation. That makes the flow patterns on the blade properly simulated and the pressure distribution of the blade, as well as the torque of the rotor, are predicted more accurately. The relative error of the predicted maximum torque is reduced from 34.4% to 3.2%. Furthermore, the procedure of calibration is applied to the MEXICO (Model Experiments in Controlled Conditions) rotor, and the predicted pressure distributions over blade sections are better than the CFD (Computational Fluid Dynamics) results from the Mexnext project. In essence, the present study provides an approach for calibrating rotor simulation using airfoil experimental data, which enhances the potential of RANS in accurate simulation of the wind turbine aerodynamic performance.

scholarly journals The aerodynamics of the curled wake: a simplified model in view of flow control

2019 ◽  
Vol 4 (1) ◽  
pp. 127-138 ◽  
Author(s):  
Luis A. Martínez-Tossas ◽  
Jennifer Annoni ◽  
Paul A. Fleming ◽  
Matthew J. Churchfield
Keyword(s):  
Boundary Layer ◽  
Wind Farm ◽  
Stokes Equations ◽  
Large Eddy Simulations ◽  
Simplified Model ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Actuator Disk ◽  
Large Eddy ◽  
Good Agreement

Abstract. When a wind turbine is yawed, the shape of the wake changes and a curled wake profile is generated. The curled wake has drawn a lot of interest because of its aerodynamic complexity and applicability to wind farm controls. The main mechanism for the creation of the curled wake has been identified in the literature as a collection of vortices that are shed from the rotor plane when the turbine is yawed. This work extends that idea by using aerodynamic concepts to develop a control-oriented model for the curled wake based on approximations to the Navier–Stokes equations. The model is tested and compared to time-averaged results from large-eddy simulations using actuator disk and line models. The model is able to capture the curling mechanism for a turbine under uniform inflow and in the case of a neutral atmospheric boundary layer. The model is then incorporated to the FLOw Redirection and Induction in Steady State (FLORIS) framework and provides good agreement with power predictions for cases with two and three turbines in a row.

Wake Comparison of Open and Ducted Wind Turbines Using Actuator Disc Simulations

2020 ◽  
Author(s):  
Nojan Bagheri-Sadeghi ◽  
Brian T. Helenbrook ◽  
Kenneth D. Visser
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Turbulence Intensity ◽  
Stokes Equations ◽  
Rotor Blades ◽  
Energy Output ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Actuator Disc ◽  
Power And Energy

Abstract Shrouding a wind turbine inside a duct can significantly augment its power and energy output by increasing the mass flow rate through the rotor and decreasing the cut-in speed. Whether this is an advantage in a turbine array depends on the wake recovery behavior and how this compares to open wind turbines. Axisymmetric CFD simulations using the Reynolds-Averaged Navier-Stokes equations with a k–ω SST turbulence closure were used to compare the wake behavior of open and ducted wind turbines. For both cases, the rotor blades were modeled using an actuator disc. Simulations of open wind turbines revealed significant sensitivity of the wake behavior to the mean turbulence intensity at the rotor. Better agreement with experimental data for the far wake was obtained when the turbulence intensity at the rotor was comparable to values measured experimentally. It was observed that compared to an open wind turbine with similar power output, a DWT has a significantly slower wake recovery. This was attributed to the extra momentum deficit of the wake due to the drag force on the duct.

Asymptotic analysis of a linearized trailing edge flow

1972 ◽  
Vol 6 (3) ◽  
pp. 327-347 ◽  
Author(s):  
K. Capell
Keyword(s):  
Boundary Layer ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Wake Region ◽  
Trailing Edge ◽  
Navier Stokes Equations ◽  
Uniform Shear ◽  
Uniform Shear Flow ◽  
Appl Math ◽  
Edge Flow

An Oseén type linearization of the Navier-Stokes equations is made with respect to a uniform shear flow at the trailing edge of a flat plate. Asymptotic expansions are obtained to describe a symmetrical merging flow for distances from the trailing edge that are, in a certain sense, large. Expansions for three regions are found:(i) a wake region,(ii) an inviscid region, and(iii) an upstream lower order boundary layer.The results are compared with those of Hakkinen and O'Neil (Douglas Aircraft Co. Report, 1967) and Stewartson (Proc. Roy. Soc. Ser. A 306 (1968)). They are further related to the results of Stewartson (Mathematika 16 (1969)) and Messiter (SIAM J. Appl. Math. 18 (1970)).

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