A general purpose parallel block structured open source incompressible flow solver

Mendina, Mariana; Draper, Martín; Soares, Ana Paula Kelm; Narancio, Gabriel; Usera, Gabriel

doi:10.1007/s10586-013-0323-2

Cited by 34 publications

(26 citation statements)

References 12 publications

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“…The heavy-tailed distributions are the statistical description of large velocity changes over given timescales and are transferred to turbines in terms of loads and power output. This has been shown experimentally (Schottler et al, 2017c), numerically (Mücke et al, 2011) and in a field study by Milan et al (2013). Consequently, our findings should be considered in wind farm layout optimization approaches, where a wake's width is a crucial parameter for radial turbine spacing.…”

Section: Discussionsupporting

confidence: 69%

“…Investigating their probability density function (PDF) allows for scale-dependent analyses of turbulent flows, including all higher-order moments of u τ , and hence all structure functions of order n, S n τ = u n τ of a velocity time series (Frisch, 1995). The impact of certain properties of velocity increment PDFs on wind turbines is to date a widely discussed topic in wind energy research (see, e.g., Mücke et al, 2011;Milan et al, 2013;Berg et al, 2016;Schottler et al, 2017c). For more details, we refer the reader to Morales et al (2012) Figure 4.…”

Section: Examined Quantitiesmentioning

confidence: 99%

“…Similarly, Mücke et al (2011) found a transfer of intermittency to torque data using a generic turbine model. Milan et al (2013) reported intermittent power data in a full-scale wind farm. We thus believe that distributions of velocity increments in wakes are of importance for potential downstream turbines as non-Gaussian characteristics are likely to be transferred to wind turbines in terms of fluctuating loads and power output.…”

Section: Introductionmentioning

confidence: 99%

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Wind tunnel experiments on wind turbine wakes in yaw: redefining the wake width

et al. 2018

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Abstract. This paper presents an investigation of wakes behind model wind turbines, including cases of yaw misalignment. Two different turbines were used and their wakes are compared, isolating effects of boundary conditions and turbine specifications. Laser Doppler anemometry was used to scan full planes of wakes normal to the main flow direction, six rotor diameters downstream of the respective turbine. The wakes of both turbines are compared in terms of the time-averaged main flow component, the turbulent kinetic energy and the distribution of velocity increments. The shape of the velocity increments' distributions is quantified by the shape parameter λ2. The results show that areas of strongly heavy-tailed distributed velocity increments surround the velocity deficits in all cases examined. Thus, a wake is significantly wider when two-point statistics are included as opposed to a description limited to one-point quantities. As non-Gaussian distributions of velocity increments affect loads of downstream rotors, our findings impact the application of active wake steering through yaw misalignment as well as wind farm layout optimizations and should therefore be considered in future wake studies, wind farm layout and farm control approaches. Further, the velocity deficits behind both turbines are deformed to a kidney-like curled shape during yaw misalignment, for which parameterization methods are introduced. Moreover, the lateral wake deflection during yaw misalignment is investigated.

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Section: Discussionsupporting

confidence: 69%

Section: Examined Quantitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Wind tunnel experiments on wind turbine wakes in yaw: redefining the wake width

et al. 2018

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“…The incompressible flow solver caffa3d.MBRi as described by Mendina et al (2014) and Draper et al (2016) was used to obtain the results shown in Figure B1 …”

Section: Appendix B: Les Simulationsmentioning

confidence: 99%

Wind tunnel experiments on wind turbine wakes in yaw: Redefining the wake width

Schottler¹,

Bartl²,

Mühle³

et al. 2018

Preprint

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Abstract. This paper presents an investigation of wakes behind model wind turbines, including cases of yaw misalignment. Two different turbines were used and their wakes are compared, isolating effects of boundary conditions and turbine specifications. The results show that areas of strongly heavy-tailed distributed velocity increments are surrounding the velocity deficit in all cases examined. Thus, a wake is significantly wider when two-point statistics are included as opposed to a description limited to one-point quantities. As non-Gaussian distributions of velocity increments affect loads of downstream rotors, our findings impact the application of active wake steering through yaw misalignment as well as wind farm layout optimizations and should 10 therefore be considered in future wake studies, wind farm layout and farm control approaches. Further, the velocity deficits behind both turbines are deformed to a kidney-like curled shape during yaw misalignment, for which parameterization methods are introduced. Moreover, the lateral wake deflection during yaw misalignment is investigated.

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“…Further details about the code can be found in (Schito and Zasso, 2014). wind energy simulations can be found in (Guggeri et al, 2017;Mendina et al, 2014;Usera et al, 2008).…”

mentioning

confidence: 99%

Blind test comparison on the wake behind a yawed wind turbine

Mühle¹,

Schottler²,

Bartl³

et al. 2018

Preprint

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This article summarizes the results of a fifth Blind test workshop, which was held in Visby, Sweden, in May 2017.This study compares the numerical predictions of the wake flow behind a model wind turbine operated in yaw to experimental wind tunnel results. Prior to the work shop, research groups were invited to predict the turbines' performances and wake flow properties using computational fluid dynamics (CFD) methods. For this purpose, the power, thrust and yaw moments for a 30 • yawed model turbine as well as the wake's mean and turbulent streamwise and vertical flow components were measured 5 in the wind tunnel at the Norwegian University of Science and Technology (NTNU). In order to increase the complexity, a non-yawed downstream turbine was added in a second test case, while a third test case challenged the modelers with a new rotor and turbine geometry. Four participants submitted predictions using different flow solvers, three of which were based on Large Eddy Simulations (LES) while another one used an Improved Delayed Detached Eddy Simulation (IDDES) model. The performance of a single 10 yawed turbine was fairly well predicted by all simulations, both in the first and third test case. The scatter in the downstream turbine's performance predictions in the second test case, however, was found to be significantly larger. The complex asymmetric shape of the mean streamwise and vertical velocity was generally well predicted by all the simulations for all test cases.The largest improvement with respect to previous Blind tests is the good prediction of the levels of turbulent kinetic energy in the wake, even for the complex case of yaw misalignment. These very promising results confirm the mature development 15 stage of LES/DES simulations for wind turbine wake modeling, while competitive advantages might be obtained by faster computational methods.

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A general purpose parallel block structured open source incompressible flow solver

Cited by 34 publications

References 12 publications

Wind tunnel experiments on wind turbine wakes in yaw: redefining the wake width

Wind tunnel experiments on wind turbine wakes in yaw: redefining the wake width

Wind tunnel experiments on wind turbine wakes in yaw: Redefining the wake width

Blind test comparison on the wake behind a yawed wind turbine

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