Abstract The wake of a wind turbine operating in uniform inflow at various tip speed ratios is simulated using numerical method, which combines large eddy simulations with an actuator line technique. computations are carried out mesh about 8.4·10 6 grid points distributed to facilitate detailed studies basic features both the near and far wake, including distributions interference factors, vortex structures formation instabilities. Copyright © 2009 John Wiley & Sons, Ltd.

The wake of a wind turbine operating in an atmospheric turbulent inflow without mean shear is simulated using numerical method, which combines large eddy simulations with actuator line technique. A the same spectral characteristics as atmosphere produced by introducing time varying body forces plane upstream rotor. results simulation are compared to those obtained on uniform at speed and from this comparison number features influence turbulence dynamics deduced. Furthermore, used verify...

ABSTRACT A simple model for including the influence of atmospheric boundary layer in connection with large eddy simulations wind turbine wakes is presented and validated by comparing computed results measurements as well direct numerical simulations. The based on an immersed type technique where volume forces are used to introduce shear turbulence. application wake studies demonstrated combining it actuator line method, predictions compared field measurements. Copyright © 2013 John Wiley...

As the major part of new wind turbines are installed in clusters or farms, there is a strong need for reliable and accurate tools predicting increased loadings due to wake operation associated reduced power production. The dynamic meandering (DWM) model has been developed on this background, basic physical mechanisms wake—i.e., velocity deficit, added turbulence—are modeled as simply possible order make fast computations. In present paper, DWM presented version suitable full integration an...

Abstract An improved k ‐ ϵ turbulence model is developed and applied to a single wind turbine wake in neutral atmospheric boundary layer using Reynolds averaged Navier–Stokes solver. The proposed includes flow‐dependent C μ that sensitive high velocity gradients, e.g., at the edge of wake. modified compared with original eddy viscosity model, Large‐Eddy Simulations field measurements eight test cases. comparison shows deficits, predicted by are much closer ones calculated Simulation those...

ABSTRACT The phenomenon of wake interaction between two wind turbines was analysed using the actuator line technique and full unsteady Navier–Stokes computations. Results are presented for varying mutual distances both half situations were considered. Furthermore, simulations carried out at different degrees ambient turbulence intensity representing laminar, offshore onshore conditions. From simulations, main characteristics interacting wakes extracted including averaged velocity fields as...

ABSTRACT Wind turbine wake can be studied in computational fluid dynamics with the use of permeable body forces (e.g. actuator disc, line and surface). This paper presents a general flexible method to redistribute wind blade as domain. The take any kind shape discretization, determine intersectional elements grid size these proportionally forces. potentially reduce need for mesh refinement region surrounding rotor and, therefore, also cost large farm simulations. special case disc is...

Abstract The induction zone in front of different wind turbine rotors is studied by means steady‐state Navier‐Stokes simulations combined with an actuator disk approach. It shown that, for distances beyond 1 rotor radius upstream the rotors, induced velocity self‐similar and independent geometry. On basis these findings, a simple analytical model turbines proposed.

Abstract The wake of the 5MW reference wind turbine designed by National Renewable Energy Laboratory (NREL) is simulated using computational fluid dynamics with a fully resolved rotor geometry, an actuator line method and disc method, respectively. Simulations are carried out prescribing both uniform turbulent inflows, properties predicted three models compared. In inflow, methods found to be in very close agreement but differ significantly from rotor, which characterized much higher...

A comprehensive computational study, in both steady and unsteady flow conditions, has been carried out to investigate the aerodynamic characteristics of Risø-B1-18 airfoil equipped with variable trailing edge geometry as produced by a hinged flap. The function such flaps should be decrease fatigue-inducing oscillations on blades. computations were conducted using 2D incompressible RANS solver k-w turbulence model under assumption fully developed turbulent flow. investigations at Reynolds...

The effect of wake interaction for a row three wind turbines in farm is analysed using the actuator line technique. Both full and half situations are considered with aim deriving optimal pitch setting foremost turbine, respect to total power from row. mutual distance between 5 diameters operate shear an exponent 0.15, rotor centre located at 1.4 radii ground. main findings reveal clear effects reducing loading on turbine towards increased production 2 3

The newly developed k-ε-fP eddy viscosity model is applied to double wind turbine wake configurations in a neutral atmospheric boundary layer, using Reynolds averaged Navier-Stokes solver.The turbines are represented by actuator disks.A proposed variable disk force method employed estimate the power production of interacting and results compared with two existing methods; based on tabulated airfoil data axial induction from 1D momentem theory.The calculates correct power, while other methods...

The recently developed k-ε-fP eddy-viscosity model is applied to one on-shore and two off-shore wind farms.The results are compared with power measurements of the standard k-ε model.In addition, direction uncertainty used correct a Gaussian filter.The underpredicts deficit first downstream turbines, whereas eddyviscosity shows good agreement measurements.However, difference in predicted by turbulence models becomes smaller for turbines that located further downstream.Moreover, between...

In the present paper, single-wake dynamics have been studied both experimentally and numerically. The use of pulsed lidar measurements allows for validation basic dynamic wake meandering modeling assumptions. Wake center tracking is used to estimate advection velocity obtain an expansion in a fixed frame reference. A comparison shows good agreement between measured average Computational Fluid Dynamics (CFD) large eddy simulation–actuator line computations. Frandsen's model seems predict...

The blockage developing in front of a laterally aligned row wind turbines and its impact on power production over single turbine was analysed using two different numerical methods.The inflow direction varied from orthogonal to the until 45 • , with turning into wind, thereby resembling testing site or park.The methods included computational fluid dynamics (CFD) an actuator disc representation rotor simple vortex method.The forces were either derived airfoil data modern set as constant.For...

We present Large-Eddy Simulation results of a turbine wake in realistic complex terrain with slopes above 0.5. By comparing simulations including and without the wind we can estimate induction factor, a, show how presence strong recirculation zone dictates positioning wake. This last finding is contrast to what would happen gentle no substantial increase turbulent kinetic energy induced wakes.

Abstract Actuator disc and actuator line techniques are widely used for modelling wind turbines operating in farms. These essentially replace the blade geometry with applied body forces, which reduce resolved length scales significantly hence required grid resolution. This work is a verification of coupling between flow solver EllipSys3D aeroelastic tool Flex5, through quantitative comparison coupled line, disc, standalone Flex5. Steady state performance predictions, instantaneous reaction...

The actuator line method is a widely used technique to model wind turbines in computational fluid dynamics, as it significantly reduces the required expense comparison simulations using geometrically resolved blades. Actuator coupled an aeroelastic solver enables not only study of detailed wake dynamics but also loads, flexible blade deformation and how this interacts with flow. Validating predictions loading, deflection turbine wakes complex inflow scenarios particularly relevant for modern...

Experimental results and complimentary computations for airfoils with vortex generators are compared in this paper, as part of an effort within the AVATAR project to develop tools wind turbine blade control devices. Measurements from two equipped passive generators, a 30% thick DU97W300 18% NTUA T18 have been used benchmarking several simulation tools. These span low-to-high complexity, ranging engineering-level integral boundary layer fully-resolved computational fluid dynamics codes....

Abstract In this paper, wake interaction resulting from two stall regulated turbines aligned with the incoming wind is studied experimentally and numerically. The experimental work based on a full‐scale remote sensing campaign involving three nacelle mounted scanning lidars. A thorough analysis interpretation of measurements performed to overcome either lack or poor calibration relevant turbine operational sensors, as well other uncertainties inherent in resolving wakes experiments....

Abstract. We perform large eddy simulation of flow in a complex terrain under neutral atmospheric stratification. study the self-similar behavior turbine wake as function varying complexity and comparisons with flat terrain. By plotting normalized velocity deficit profiles different cases, we verify that self-similarity is preserved move downstream from turbine. find this preservation valid for shorter distance compared to what observed A larger spread toward tails due levels shear also observed.