Aero-elastic analysis of wind turbines under turbulent inflow conditions

Guma, Giorgia; Bangga, Galih; Lutz, Thorsten; Krämer, Ewald

doi:10.5194/wes-2020-22

Cited by 2 publications

(2 citation statements)

References 13 publications

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“…2 shows the surface structures of the fully meshed wind turbine integrated into the background mesh with the chimera technique (Benek et al, 1986). For the mesh of the rigid turbine, reference is made to Guma et al (2018) and Guma et al (2020). As for the ground of the terrain, the no-slip wall boundary conditions were introduced for the surfaces of the turbine.…”

Section: Setup For the Comparisons With Measurementsmentioning

confidence: 99%

CFD Studies on Wind Turbine Interactions with the Turbulent Local Flow Field Influenced by Complex Topography and Thermal Stratification

Letzgus

Guma

Lutz

2021

Preprint

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Abstract. This paper shows the results of CFD studies of turbulent flow fields and their effects on a wind turbine in complex terrain. As part of the WINSENT project a research test site comprising four meteorological masts and two research wind turbines is currently being constructed in the Swabian Alps in Southern Germany. This work is an essential part of the research of the Southern German wind energy research cluster WindForS. The terrain site is characterised by a densely forested escarpment and a flat plateau downstream of the slope. The met masts and wind turbines are built on this plateau. In the first part, high-resolution CFD simulations are performed to separately investigate the effects of the forested escarpment and of thermal stratification on the flow field and on the wind turbine accordingly. In the second part, all the examined effects are combined for a real-life case dated March 2021. There, unstable conditions prevailed and the forest shows low leaf area densities due to the wintertime. It is shown that atmospheric turbulence, forests, orographies, and thermal stratification must be considered when assessing the impact of wind turbines in complex terrain. All of these effects influence the flow field both at the turbine position as well as in its wake. Turbulent structures of the forest wake cross the rotor plane temporarily and thereby affect the turbine inflow. Moreover, convective conditions and upward flows caused by the orography have an impact on the performance output as inclined flows result in asymmetric torque distributions. The wind turbine wake and the forest wake mix further downstream, resulting in a fast decay of the turbine wake. The paper also describes how the turbulent flow in the wake changes in the presence of thermal stratification.

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Section: Setup For the Comparisons With Measurementsmentioning

confidence: 99%

CFD Studies on Wind Turbine Interactions with the Turbulent Local Flow Field Influenced by Complex Topography and Thermal Stratification

Letzgus

Guma

Lutz

2021

Preprint

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“…Additionally, the study concluded that, for the specific turbine and flow cases, inclusion of blade flexibility does not impact highly the wake behaviour, whereas inflow turbulence have high impacts on wake diffusion. Guma et al (Guma et al, 2020) recently published a study looking into the aero-elastic response of the NM80 rotor, also studied in the present article, in turbulent inflow. Here, synthetic Mann box turbulence and the delayed detached eddy simulation (DDES) turbulence model were used to create and resolve turbulent structures in the wind flow.…”

Section: Introductionmentioning

confidence: 99%

Wind turbines in atmospheric flow – FSI simulations with hybrid LES-IDDES turbulence modelling

Grinderslev¹,

Sørensen²,

Horcas³

et al. 2020

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Abstract. In order to design future large wind turbines, knowledge is needed about the impact of aero-elasticity on the rotor loads and performance, and about the physics of the atmospheric flow surrounding the turbines. The objective of the present work is to study both effects by means of high fidelity rotor-resolved numerical simulations. In particular, unsteady computational fluid dynamics (CFD) simulations of a 2.3 MW wind turbine rotor are conducted, this rotor being the largest design with relevant experimental data available to the authors. Turbulence is modeled with two different approaches. On one hand, the well established improved delayed detached eddy simulation (IDDES) model is employed. An additional set of simulations relies on a novel hybrid turbulence model, developed within the framework of the present work. It consists on the blending of a large eddy simulation (LES) model for atmospheric flow by Deardorff with an IDDES model for the separated flow near the rotor geometry. In the same way, the assessment of the influence of the blade flexibility is performed by comparing two different sets of computations. A first group accounts for a structural multi body dynamic (MBD) model of the blades. The MBD solver was coupled to the CFD solver during run time with a staggered fluid structure interaction (FSI) scheme. The second set of simulations uses the original rotor geometry, without accounting for any structural deflection. The results of the present work show no significant difference between the IDDES and the hybrid turbulence model. However, it is expected that future simulations of more complex stratification and longer domains will benefit from the developed hybrid model. In a similar manner, and due to the fact that the considered rotor was relatively stiff, the loading variation introduced by the blade flexibility was found to be negligible when compared to the influence of inflow turbulence. The simulation method validated here is considered highly relevant for future turbine designs, where the impact of blade elasticity will be significant and the detailed structure of the atmospheric inflow will be important.

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Aero-elastic analysis of wind turbines under turbulent inflow conditions

Cited by 2 publications

References 13 publications

CFD Studies on Wind Turbine Interactions with the Turbulent Local Flow Field Influenced by Complex Topography and Thermal Stratification

CFD Studies on Wind Turbine Interactions with the Turbulent Local Flow Field Influenced by Complex Topography and Thermal Stratification

Wind turbines in atmospheric flow – FSI simulations with hybrid LES-IDDES turbulence modelling

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