Scaled wind turbine setup in a turbulent wind tunnel

Berger, Frederik; Kröger, Lars; Onnen, David; Petrović, Vlaho; Kühn, Martin

doi:10.1088/1742-6596/1104/1/012026

Cited by 22 publications

(16 citation statements)

References 4 publications

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“…A downscaling of the fluctuations of the wind speed time series to match a model wind turbine is realized by speeding up the time series in the wind tunnel. As an example for the downscaling of the model wind turbine Oldenburg (MoWiTO 1.8) [15] to the NREL 5MW reference turbine we obtain a linear scaling factor of about 68. The main challenge now is to create such a motion protocol which produces a predetermined wind speed time series in a wind tunnel.…”

Section: Motion Protocolmentioning

confidence: 87%

Taming chaos with active grids -- Reproducibility in turbulent wind tunnel experiments

Kröger,

Hölling,

Gülker

et al. 2021

Preprint

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A wind tunnel experiment is shown to examine the reproducibility of generated wind fields in the laboratory utilizing an active grid. A motion protocol of the grid, designed to mimic a measured atmospheric wind speed time series, is therefore repeated 50 times and the flow is measured by a 2D hotwire (x-wire) system. The acquired wind speed time series are analysed in two different ways to identify the reproducible time scales. A direct comparison using the cross covariance function combined with two filtering methods and a statistic approach using one and two point analysis. Like that the reproducible time and length scales could be linked to the active grid motion and design. The identification of the reproducible time scales of a turbulent signal generated by means of an active grid is suitable to improve the possible wind fields in laboratory experiments.

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Section: Motion Protocolmentioning

confidence: 87%

Taming chaos with active grids -- Reproducibility in turbulent wind tunnel experiments

Kröger,

Hölling,

Gülker

et al. 2021

Preprint

Self Cite

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“…The turbine control and data acquisition is handled by a National Instruments Compact Rio system. The turbine scaling and design are described in detail in Berger et al (2018).…”

Section: Model Turbinementioning

confidence: 99%

Experimental analysis of the dynamic inflow effect due to coherent gusts

Berger¹,

Neuhaus²,

Onnen³

et al. 2022

Preprint

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Abstract. The dynamic inflow effect describes the unsteady aerodynamic response to fast changes in rotor loading, due to the inertia of the wake. For pitch actuation and fast rotor speed changes this effect leads to load overshoots. The effect is suspected to be also relevant for gust situations, however this was never shown. The objective of the paper is to proove the dynamic inflow effect due to gusts and compare dynamic inflow engineering models to corresponding measurements. A 1.8 m diameter model turbine is used in the large wind tunnel of ForWind – University of Oldenburg with an active grid to impress rotor uniform gusts on the flow. The campaign features load and velocity measurements of the axial flow in the rotor plane. The unsteady dynamic inflow effect is investigated by comparing two experimental cases. Firstly, a dynamic measurement during a gust situation is performed. Secondly, quasi-steady loads and axial velocities are interpolated from a steady characterisation experiment according to the gust wind speed. By comparing both cases, the influence attributed to the dynamic inflow effect is isolated. Further comparisons to a typical Blade Element Momentum code and a higher fidelity Free VortexWake Model are performed. Based on analytical considerations an improvemed formulation of the Øye dynamic inflow model is proposed. The experiment shows a dynamic inflow effect due to gusts in the loads and axial velocity measurements. It leads to a reduction in load and axial velocity amplitudes and consequently also lower fatigue loading. The higher fidelity model shows a similar impact of the dynamic inflow effect. In contrast, the commonly used Øye engineering model in the BEM code predicts an increase in load amplitude and thus higher fatigue loads. The improved Øye engineering model however catches the observed dynamic inflow effect due to gusts in accordance to the experiment and FVWM simulations. An amplification of induced velocities, seen in the experiment and FVWM simulation, causes the reduced load amplitudes. Therefore, classic dynamic inflow models, which filter the induced velocity, cannot predict the effect. The proposed improvement to additionally consider the wake velocity for the filter of the dynamic inflow engineering model, proves to be a straight forward but also effective modification. In conclusion, these new experimental findings on dynamic inflow due to gusts and improvements to the Øye model enable improvements in wind turbine design by catching the related lower fatigue loads.

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“…The concept is based on the use of a three-bladed wind turbine model described in detail in Berger et al (2018). The scaling factor of the rotor blade length is 1:70, so the rotor blades made are 90 cm long.…”

Section: Concept and Realisationmentioning

confidence: 99%

Measurement of Fluid-Structure Interaction of Wind Turbines in Wind Tunnel Experiments: Concept and First Results

Nietiedt

Goering

Willemsen

et al. 2019

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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Abstract. Fluid-structure interactions are crucial for the design of rotor blades of wind power systems. Up to now, the mutual interactions between rotor blades and turbulent wind flows have been treated by complex simulations or were observed at individual discrete points. In this paper, a measurement concept is presented where spatial information of the motion/deformation of a rotating wind turbine as well as the wind flow are recorded in wind tunnel experiments. Wind flow and motion behaviour are recorded simultaneously and contactless. Techniques from the field of photogrammetry and flow measurement techniques are combined, resulting in high demands on the measurement concept. Furthermore, solutions for the realisation of a common coordinate system as well as for the synchronisation of both measuring systems are presented. In addition, the validation of the entire measurement concept is carried out based on of some wind tunnel tests in which a single rotor blade is used for the moment. This showed that the measurement concept and the proposed solutions for the simultaneous recording of wind flows and rotor blade movements are suitable in principle and that movements can be recorded and reconstructed with high accuracy.

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Scaled wind turbine setup in a turbulent wind tunnel

Cited by 22 publications

References 4 publications

Taming chaos with active grids -- Reproducibility in turbulent wind tunnel experiments

Taming chaos with active grids -- Reproducibility in turbulent wind tunnel experiments

Experimental analysis of the dynamic inflow effect due to coherent gusts

Measurement of Fluid-Structure Interaction of Wind Turbines in Wind Tunnel Experiments: Concept and First Results

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