Advances in large-eddy simulation of a wind turbine wake

Jiménez, A.; Crespo, António; Migoya, E.; Garcı́a, Javier Garcı́a

doi:10.1088/1742-6596/75/1/012041

Cited by 203 publications

(177 citation statements)

References 13 publications

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“…At a free-stream speed of 10m/s the tip vortices have only just broken down at 7 rotor diameters (7D) as shown in Figure 4. Other simulations used sufficiently large domains but reported data in a longitudinal plane, which does not give much information about wake structure (Jimenez et al 2007, Porté-Agel et al 2011, Zahle & Sørensen 2007. However when using longitudinal data the turbulence intensity can be still be seen to change at least 3% across the rotor at 7 rotor diameters in wind tunnel measurements, indicating some level of increased unsteady loading (Porté-Agel et al 2011).…”

Section: Wake Structure and Propagationmentioning

confidence: 99%

“…This approach is much faster than full modelling of the blades, and suitable for most applications but occasionally insufficient. Recently large-eddy simulations (LES) of the wakes of horizontal-axis wind turbines have been conducted (Bazilevs et al 2011, Jimenez et al 2007, Hsu et al 2013, Porté-Agel et al 2011, Sezer-Uzol & Long 2006. This is a turbulence model that directly resolves large-scale eddies and models smaller ones, eliminating the extra computational cost of simulating very small scale turbulence.…”

Section: Introductionmentioning

confidence: 99%

“…This is a turbulence model that directly resolves large-scale eddies and models smaller ones, eliminating the extra computational cost of simulating very small scale turbulence. There is often cross-over in these approaches, with LES studies using actuator line or disc methods (Jimenez et al 2007, Porté-Agel et al 2011. Using simplified approaches instead of modelling the blades directly may lead to missed details in the wake flow-field and airfoil noise.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A discussion of wind turbine interaction and stall contributions to wind farm noise

Laratro

Arjomandi

Kelso

et al. 2014

Journal of Wind Engineering and Industrial Aerodynamics

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Elsevier's Policy: An author may use the preprint for personal use, internal institutional use and for permitted scholarly posting. ... Elsevier's AAM Policy: Authors retain the right to use the accepted author manuscript for personal use, internal institutional use and for permitted scholarly posting provided that these are not for purposes of commercial use or systematic distribution. Elsevier believes that individual authors should be able to distribute their AAMs for their personal voluntary needs and interests, e.g. posting to their websites or their institution's repository, e-mailing to colleagues. However, our policies differ regarding the systematic aggregation or distribution of AAMs to ensure the sustainability of the journals to which AAMs are submitted. Therefore, deposit in, or posting to, subject-oriented or centralized repositories (such as PubMed Central), or institutional repositories with systematic posting mandates is permitted only under specific agreements between Elsevier and the repository, agency or institution, and only consistent with the publisher's policies concerning such repositories. Voluntary posting of AAMs in the arXiv subject repository is permitted. ... Highlights-Rotor-wake interaction plays a role in wind farm noise -More wake data needs to be collected -Dynamic stall noise needs to be characterised AbstractWind farms have recently been reported to produce a noise signature that is described as possessing a "thumping" quality. Measurements of these signatures are limited and their effects are debated but their effect on public opinion and complaints make them a concern for researchers in this field. Proposed reasons for these noise signatures include amplitude modulation, interference patterns and wake-rotor interaction. This paper discusses these effects and concludes that wake-rotor interaction plays a role by causing variations in turbulent-inflow noise and dynamic stall. The current state of research into stall noise and wind turbine wake structure is also reviewed and it is concluded that the available information and collected data on wind turbine wake are insufficient to determine how strong this role is. More information on the velocity and turbulence fields in the wake of horizontal-axis wind turbines as well as a characterisation of the noise produced by an airfoil experiencing dynamic stall is required in order to make a full assessment of rotor-wake contributions to wind farm noise.2

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Section: Wake Structure and Propagationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A discussion of wind turbine interaction and stall contributions to wind farm noise

Laratro

Arjomandi

Kelso

et al. 2014

Journal of Wind Engineering and Industrial Aerodynamics

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“…In recent years, LES has also been applied to study turbulent flow in and around wind turbines and wind farms (see, e.g. Jimenez et al 2007Jimenez et al , 2008Calaf et al 2010;Wu & Porté-Agel 2011). In the current study, we use large-eddy simulations to study wind farms in conventionally neutral boundary layers (CNBLs), which are often encountered in offshore conditions.…”

Section: Introductionmentioning

confidence: 99%

Boundary-layer development and gravity waves in conventionally neutral wind farms

2017

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While neutral atmospheric boundary layers are rare over land, they occur frequently over sea. In these cases they are almost always of the conventionally neutral type, in which the neutral boundary layer is capped by a strong inversion layer and a stably stratified atmosphere aloft. In the current study, we use large-eddy simulations (LES) to investigate the interaction between a large wind farm that has a fetch of 15 km and a conventionally neutral boundary layer (CNBL) in typical offshore conditions. At the domain inlet, we consider three different equilibrium CNBLs with heights of approximately 300 m, 500 m and 1000 m that are generated in a separate precursor LES. We find that the height of the inflow boundary layer has a significant impact on the wind farm flow development. First of all, above the farm, an internal boundary layer develops that interacts downwind with the capping inversion for the two lowest CNBL cases. Secondly, the upward displacement of the boundary layer by flow deceleration in the wind farm excites gravity waves in the inversion layer and the free atmosphere above. For the lower CNBL cases, these waves induce significant pressure gradients in the farm (both favourable and unfavourable depending on location and case). A detailed energy budget analysis in the turbine region shows that energy extracted by the wind turbines comes both from flow deceleration and from vertical turbulent entrainment. Though turbulent transport dominates near the end of the farm, flow deceleration remains significant, i.e. up to 35 % of the turbulent flux for the lowest CNBL case. In fact, while the turbulent fluxes are fully developed after eight turbine rows, the mean flow does not reach a stationary regime. A further energy budget analysis over the rest of the CNBL reveals that all energy available at turbine level comes from upwind kinetic energy in the boundary layer. In the lower CNBL cases, the pressure field induced by gravity waves plays an important role in redistributing this energy throughout the farm. Overall, in all cases entrainment at the capping inversion is negligible, and also the work done by the mean background pressure gradient, arising from the geostrophic balance in the free atmosphere, is small.

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“…The force f i is added for modeling the effects of the wind turbines in the momentum equation using the "drag disk" approach in LES [5], with a new local variant [2,6]. Since simulations are done at very large Reynolds numbers and the bottom surface as well as the wind-turbine effects are parameterized, viscous stresses are neglected.…”

Section: Description Of Numerical Methodsmentioning

confidence: 99%