Modellierung wirbelerregter aeroelastischer Schwingungen für Ermüdungsnachweise bei schlanken Baustrukturen
Zusammenfassung der Projektergebnisse
Negative aerodynamic damping is the governing parameter for the onset of vortex-induced vibration (VIV). The first objective of the project was to investigate the negative aerodynamic damping of vortex induced vibrations using wind tunnel tests. These were carried out in the WISt boundary layer wind tunnel at the Ruhr-Universität Bochum. Different and complementary experimental approaches - forced vibration measurements on a sectional model, free vibration measurements on a sectional model and aeroelastic vibration of a cantilevered cylinder - are compared. None of these methods alone is sufficient to fully capture all aspects of the aeroelastic interaction in VIV, but their combination provides a clear insight into the phenomenon. The aim of this project is to calculate the response to vortex excitation using random vibration theory, which requires an equivalent linear aerodynamic damping model. The approach is consistent with forced vibration experimental results as negative aerodynamic damping is measured as a function of the root mean square of the vibration. In this way, forced vibration testing can be considered as a linearised stepwise testing technique for VIV. The response of slender structures to vortex excitation has a typical intermittent (or quasi-periodic) character due to a beat effect between the natural frequency of the structure and the vortex shedding frequency. Fatigue life is calculated using rainflow counting. Equivalent stresses can be derived that produce the same cumulative damage as the actual time histories with varying amplitude. VIV occurs not only when towers stand alone, but also when they are grouped together. In this case, depending on the relative distance between the cylinders, vortex streets develop not only behind the individual towers, but also behind the group as a whole. This interference further amplifies the vibration, particularly due to the gap flow that develops between the towers. For these reasons, specific criteria based on the experimental determination of allowable vibrations due to VIV in the presence of interference galloping are addressed. The most tangible success of this research project is the application of the concept developed for VIV to real structures. For example, the model is used to estimate the response of one of the world's largest and most powerful wind turbines, which in turn serves to validate the developed model. This validation is the subject of a subsequent DFG-funded Knowledge Transfer Project (Modellierung wirbelerregter aeroelastischer Schwingungen bei schlanken Baustrukturen: Erkenntnistransfer anhand eines großskaligen Feldversuchs an einer Windkraftanlage).
Projektbezogene Publikationen (Auswahl)
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FATIGUE LIFE ESTIMATION CONSIDERING THE QUASI-PERIODIC CROSS-WIND RESPONSE OF SLENDER STRUCTURES IN THE LOCK-IN RANGE. Proceedings of the XI International Conference on Structural Dynamics (2020), 2022-2039. American Geophysical Union (AGU).
Lupi, Francesca; Höffer, Ruediger & Niemann, Hans-Jürgen
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Prognose der Ermüdung bei Wirbelerregung am Beispiel einer Stahlkonstruktion. Baustatik – Baupraxis 14, 891-899, Universität Stuttgart, ISBN 978-3-00-064639-3, 2020
Niemann H.-J., Höffer R., Lupi F., Hubert W.
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Aerodynamic damping in vortex resonance from aeroelastic wind tunnel tests on a stack. Journal of Wind Engineering and Industrial Aerodynamics, 208, 104438.
Lupi, Francesca; Höffer, Rüdiger & Niemann, Hans-Jürgen
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Modelling VIV in the second generation of Eurocodes: an aeroelastic parameter to control the curvature of the negative aerodynamic damping. In Vortragsband der 17. Dreiländertagung D-A-CH 2021 der Windtechnologischen Gesellschaft e. V. am 25. und 26. Oktober 2021 an der Ruhr-Universität Bochum, WtG- Berichte 17, ISBN 3-928909-16-9, 2021
Lupi F., Höffer R., Niemann H.-J.
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Aktuelle Modelle und Methoden zur Windlastermittlung. Stahlbau Kalender 2022 (2022, 4, 6), 577-639. American Geophysical Union (AGU).
Höffer, Rüdiger; Thiele, Klaus; Lupi, Francesca; Winkelmann, Ulf; Hubert, Wolfgang; Kalender, Cornelia; Wüchner, Roland & Chen, Cong
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Field pressure measurements on a wind turbine tower in the transcritical range of Reynolds numbers. Proceedings of the 8th European African Conference on Wind Engineering (8EACWE) held in Bucharest (Romania) in September 2022. Editors Ileana Calotescu, Adriana Chitez, Costin Coşoiu, Alexandru Cezar Vlăduţ, Conspress, 2022, ISBN 978-973-100-532-4
Kurniawati I., Lupi F., Seidel M., Niemann H.-J., Höffer R.
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Interference effects on four freestanding circular cylinders in group arrangement. Proceedings of the 8th European African Conference on Wind Engineering (8EACWE) held in Bucharest (Romania) in September 2022. Editors Ileana Calotescu, Adriana Chitez, Costin Coşoiu, Alexandru Cezar Vlăduţ, Conspress, 2022, ISBN 978-973-100-532-4
Lupi F., Seidel M., Höffer R., Hölscher N., Niemann H.-J.
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Investigation of Vortex Induced Vibrations through full-scale and wind tunnel experiments. Book of Abstracts of the 1st CWE Workshop 2022. Advanced Modelling of Stochastic Wind Effects and Vibrations, Center for Wind and Earthquake Engineering, RTWH Aachen University, 26 October 2022
Lupi F., Kurniawati I., Niemann H.-J., Höffer R.
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Application scope of equivalent linear technique for across-wind response analysis of tall flexible structures considering nonlinear aero-elastic effect. Journal of Building Engineering, 64, 105678.
Guo, Kunpeng; Yang, Qingshan; Hui, Yi; Shan, Wenshan; Lupi, Francesca; Huang, Shuai & Hu, Weicheng
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Mitigation of Interference-Induced Vibrations for Towers in Group Arrangements. Lecture Notes in Civil Engineering (2024), 102-113. American Geophysical Union (AGU).
Lupi, Francesca; Seidel, Marc; Höffer, Rüdiger; Hölscher, Norbert & Niemann, Hans-Jürgen
