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21 results on '"Sørensen, Niels"'

5. Stability analysis of vortex-induced vibrations on wind turbines

Author

Riva, Riccardo, Horcas, Sergio G., Sørensen, Niels N., Grinderslev, Christian, and Pirrung, Georg R.

Subjects
Physics::Fluid Dynamics
Abstract

A parked wind turbine can be subjected to large yaw angles, which causes vortex shedding. Under some particular inflow conditions, the interaction between the shed vorticity and the blade structure could lead to Vortex-Induced Vibrations (VIV). VIV are an instability where the response grows until it reaches a limit cycle oscillation. In this paper, we will focus on this last part of the response. We will see that the shedding makes the aeroelastic system linear time-periodic, and study its stability with Floquet theory. We will use high-fidelity simulations of different inflow conditions, and quantify the stability of the system using a model-free approach.

Published
2022

6. CFD modeling of the Poul la Cour Tunnel

Author

Sørensen, Niels N., primary, Olsen, A. S., additional, Bak, C., additional, Gaunaa, M., additional, Beckerlee, J.S., additional, Fischer, A., additional, Mikkelsen, R.F., additional, and Ildvedsen, S., additional

Published
2020
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11. Latest results from the EU project AVATAR: Aerodynamic modelling of 10 MW wind turbines

Author

Schepers O. Ceyhan, J. G., Boorsma, K., Gonzalez, A., Munduate, X., Pires, O., Sørensen, Niels N., Ferreira, Célia Maria Dias, Sieros, G., Madsen, J., Voutsinas, S., Lutz, T., Barakos, G., Colonia, S., Heißelmann, H., Meng, F., and Croce, A.

Subjects
domain size, grid topology, Power and plant engineering (mechanical engineering), Civil and mechanical engineering computing, Numerical approximation and analysis, computational fluid dynamics, Fluid mechanics and aerodynamics (mechanical engineering), wakes, Applied fluid mechanics, boundary-elements methods, wind turbines, pressurized DNW-HDG wind tunnel, Compressible flows, shock and detonation phenomena, Mechanical engineering applications of IT, LM wind tunnel, Rotational flow, vortices, buoyancy and other flows involving body forces, Reynolds numbers, General fluid dynamics theory, simulation and other computational methods, aerospace components, Finite element analysis, Mechanical components, vortices, yawed conditions, vortex wake methods, power 10 MW, CFD calculations, grid independency, flow devices, EU project AVATAR, 3D rotor models, BEM methods, aerodynamic models, airfoil performance, aerodynamics, Numerical analysis, aerodynamic modelling
Abstract

This paper presents the most recent results from the EU project AVATAR in which aerodynamic models are improved and validated for wind turbines on a scale of 10 MW and more. Measurements on a DU 00-W-212 airfoil are presented which have been taken in the pressurized DNW-HDG wind tunnel up to a Reynolds number of 15 Million. These measurements are compared with measurements in the LM wind tunnel for Reynolds numbers of 3 and 6 Million and with calculational results. In the analysis of results special attention is paid to high Reynolds numbers effects. CFD calculations on airfoil performance showed an unexpected large scatter which eventually was reduced by paying even more attention to grid independency and domain size in relation to grid topology. Moreover calculations are presented on flow devices (leading and trailing edge flaps and vortex generators). Finally results are shown between results from 3D rotor models where a comparison is made between results from vortex wake methods and BEM methods at yawed conditions.

Published
2016

18. The Science of Making Torque from Wind 2014 (TORQUE 2014)

Author

Mann, Jakob, primary, Bak, Christian, additional, Bechmann, Andreas, additional, Bingöl, Ferhat, additional, Dellwik, Ebba, additional, Dimitrov, Nikolay, additional, Giebel, Gregor, additional, Hansen, Martin O L, additional, Juul Jensen, Dorte, additional, Larsen, Gunner, additional, Aagaard Madsen, Helge, additional, Natarajan, Anand, additional, Rathmann, Ole, additional, Sathe, Ameya, additional, Nørkær Sørensen, Jens, additional, and Nørkær Sørensen, Niels, additional

Published
2014
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