Microscale CFD Simulations of a Wind Energy Test Site in the Swabian Alps with Mesoscale Based Inflow Data

Letzgus, Patrick; Bahlouli, Asmae El; Leukauf, Daniel; Hofsäß, Martin; Lutz, Thorsten; Krämer, Ewald

doi:10.1088/1742-6596/1618/6/062021

Cited by 4 publications

(4 citation statements)

References 16 publications

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“…A large variety of measurement equipment has been used to characterize the local site-specific wind field, such as unmanned aerial systems (UAS), lidar instruments and met masts with ultrasonic anemometers. This allowed to validate CFD terrain calculations with the data from the met masts as prescribed in Letzgus et al (2020).…”

Section: Winsent Research Wind Turbinementioning

confidence: 99%

“…3, where also the presence of the forest can be noticed. The forest is modeled as additional grid structures by the use of the Chimera technique, in which force terms are added depending on the foliage density and tree height, as described in Letzgus et al (2020). In this way the modeling can be really easily adjusted to the seasonal conditions and the form of the forest.…”

Section: Cfd Model and Inflow Conditionsmentioning

confidence: 99%

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High-fidelity aeroelastic analyses of wind turbines in complex terrain: FSI and aerodynamic modelling

Guma

Bücher

Letzgus

et al. 2022

Preprint

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Abstract. This paper shows high-fidelity Fluid Structure Interaction (FSI) studies applied on the research wind turbine of the WINSENT project. In this project, two research wind turbines are going to be erected in the South of Germany in the WindForS complex terrain test field. The FSI is obtained by coupling the CFD URANS/DES code FLOWer and the multiphysics FEM solver Kratos, in which both beam and shell structural elements can be chosen to model the turbine. The two codes are coupled in both an explicit and an implicit way. The different modelling approaches strongly differ with respect to computational resources and therefore the advantages of their higher accuracy must be correlated with the respective additional computational costs. The presented FSI coupling method has been applied firstly to a single blade model of the turbine under standard uniform inflow conditions. It could be concluded that for such a small turbine, in uniform conditions a beam model is sufficient to correctly build the blade deformations. Afterwards, the aerodynamic complexity has been increased considering the full turbine with turbulent inflow conditions generated from real field data, in both a flat and complex terrains. It is shown that in these cases a higher structural fidelity is necessary. The effects of aeroelasticity are then shown on the phase-averaged blade loads, showing that using the same inflow turbulence, a flat terrain is mostly influenced by the shear, while the complex terrain is mostly affected by low velocity structures generated by the forest. Finally, the impact of aeroelasticity and turbulence on the Damage Equivalent Loading (DEL) is discussed, showing that flexibility is reducing the DEL in case of turbulent inflow, acting as a damper breaking larger cycles into smaller ones.

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Section: Winsent Research Wind Turbinementioning

confidence: 99%

Section: Cfd Model and Inflow Conditionsmentioning

confidence: 99%

High-fidelity aeroelastic analyses of wind turbines in complex terrain: FSI and aerodynamic modelling

Guma

Bücher

Letzgus

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…A large variety of measurement equipment has been used to characterize the local site-specific wind field, such as unmanned aerial systems (UASs), lidar instruments and met masts with ultrasonic anemometers. This has allowed us to validate CFD terrain calculations with the data from the met masts as prescribed in Letzgus et al (2020).…”

Section: Winsent Research Wind Turbinementioning

confidence: 99%

“…3, where the presence of the forest can also be noticed. The forest is modeled as additional grid structures by the use of the chimera technique in which force terms are added depending on the foliage density and tree height, as described in Letzgus et al (2020). In this way the modeling can be very easily adjusted to the seasonal conditions and the form of the forest.…”

Section: Cfd Model and Inflow Conditionsmentioning

confidence: 99%

High-fidelity aeroelastic analyses of wind turbines in complex terrain: fluid–structure interaction and aerodynamic modeling

et al. 2022

Self Cite

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Abstract. This paper shows high-fidelity fluid–structure interaction (FSI) studies applied to the research wind turbine of the WINSENT (Wind Science and Engineering in Complex Terrain) project. In this project, two research wind turbines are going to be erected in the south of Germany in the WindForS complex-terrain test field. The FSI is obtained by coupling the CFD URANS–DES code FLOWer and the multiphysics FEM solver Kratos Multiphysics, in which both beam and shell structural elements can be chosen to model the turbine. The two codes are coupled in both an explicit and an implicit way. The different modeling approaches strongly differ with respect to computational resources, and therefore the advantages of their higher accuracy must be correlated with the respective additional computational costs. The presented FSI coupling method has been applied firstly to a single-blade model of the turbine under standard uniform inflow conditions. It could be concluded that for such a small turbine, in uniform conditions a beam model is sufficient to correctly build the blade deformations. Afterwards, the aerodynamic complexity has been increased considering the full turbine with turbulent inflow conditions generated from real field data, in both flat and complex terrains. It is shown that in these cases a higher structural fidelity is necessary. The effects of aeroelasticity are then shown on the phase-averaged blade loads, showing that using the same inflow turbulence, a flat terrain is mostly influenced by the shear, while the complex terrain is mostly affected by low-velocity structures generated by the forest. Finally, the impact of aeroelasticity and turbulence on the damage equivalent loading (DEL) is discussed, showing that flexibility reduces the DEL in the case of turbulent inflow, acting as a damper that breaks larger cycles into smaller ones.

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Computational fluid dynamics studies on wind turbine interactions with the turbulent local flow field influenced by complex topography and thermal stratification

2022

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Abstract. This paper shows the results of computational fluid dynamics (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 test site in complex terrain 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 delayed detached eddy simulations are performed to separately investigate the effects of the forested escarpment and of thermal stratification on the flow field and accordingly on the wind turbine. In the second part, both these effects are included for a real observed case in March 2021. There, unstable conditions prevailed and the forest showed low leaf area densities due to the winter conditions. It is shown that atmospheric turbulence, forests, orographies, and thermal stratification must be considered when assessing the impact on wind turbines in complex terrain. All of these effects influence the flow field both at the turbine position and in its wake. The wind speed at the test site is accelerated by up to 60 %, which could affect the annual energy production significantly. But otherwise 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 turbine's power output as inclined flows result in asymmetric torque distributions. The wind turbine wake and the forest wake mix further downstream, resulting in a faster decay of the turbine wake than in neutral conditions or without forest. The paper also describes how the turbulent flow in the wake changes in the presence of thermal stratification, which is evident in order to be able to numerically represent the flow-physical changes in the diurnal cycle well.

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Microscale CFD Simulations of a Wind Energy Test Site in the Swabian Alps with Mesoscale Based Inflow Data

Cited by 4 publications

References 16 publications

High-fidelity aeroelastic analyses of wind turbines in complex terrain: FSI and aerodynamic modelling

High-fidelity aeroelastic analyses of wind turbines in complex terrain: FSI and aerodynamic modelling

High-fidelity aeroelastic analyses of wind turbines in complex terrain: fluid–structure interaction and aerodynamic modeling

Computational fluid dynamics studies on wind turbine interactions with the turbulent local flow field influenced by complex topography and thermal stratification

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