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Kleine, Vitor
Publications (2 of 2) Show all publications
Kleine, V., Kleusberg, E., Hanifi, A. & Henningson, D. S. (Eds.). (2019). Tip-vortex instabilities of two in-line wind turbines. Institute of Physics (IOP)
Open this publication in new window or tab >>Tip-vortex instabilities of two in-line wind turbines
2019 (English)Conference proceedings (editor) (Refereed)
Place, publisher, year, edition, pages
Institute of Physics (IOP), 2019
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-251408 (URN)
Note

QC 20190619

Available from: 2019-05-14 Created: 2019-05-14 Last updated: 2019-06-19Bibliographically approved
Kleine, V., Kleusberg, E., Hanifi, A. & Henningson, D. S. (2019). Tip-vortex instabilities of two in-line wind turbines. In: Wake Conference 201922–24 May 2019, Visby, Sweden: . Paper presented at Wake Conference 2019; Uppsala University's Gotland Campus, Visby; Sweden; 22 May 2019 through 24 May 2019. Institute of Physics Publishing (IOPP), 1256(1), Article ID 012015.
Open this publication in new window or tab >>Tip-vortex instabilities of two in-line wind turbines
2019 (English)In: Wake Conference 201922–24 May 2019, Visby, Sweden, Institute of Physics Publishing (IOPP), 2019, Vol. 1256, no 1, article id 012015Conference paper, Published paper (Refereed)
Abstract [en]

The hydrodynamic stability of a vortex system behind two in-line wind turbines operating at low tip-speed ratios is investigated using the actuator-line method in conjunction with the spectral-element flow solver Nek5000. To this end, a simplified setup with two identical wind turbine geometries rotating at the same tip-speed ratio is simulated and compared with a single turbine wake. Using the rotating frame of reference, a steady solution is obtained, which serves as a base state to study the growth mechanisms of induced perturbations to the system. It is shown that, already in the steady state, the tip vortices of the two turbines interact with each other, exhibiting the so-called overtaking phenomenon. Hereby, the tip vortices of the upstream turbine overtake those of the downstream turbine repeatedly. By applying targeted harmonic excitations at the upstream turbine's blade tips a variety of modes are excited and grow with downstream distance. Dynamic mode decomposition of this perturbed flow field showed that the unstable out-of-phase mode is dominant, both with and without the presence of the second turbine. The perturbations of the upstream turbine's helical vortex system led to the destabilization of the tip vortices shed by the downstream turbine. Two distinct mechanisms were observed: for certain frequencies the downstream turbine's vortices oscillate in phase with the vortex system of the upstream turbine while for other frequencies a clear out-of-phase behaviour is observed. Further, short-wave instabilities were shown to grow in the numerical simulations, similar to existing experimental studies [1].

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2019
Series
Journal of Physics: Conference Series, ISSN 1742-6588
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-262574 (URN)10.1088/1742-6596/1256/1/012015 (DOI)2-s2.0-85070017009 (Scopus ID)
Conference
Wake Conference 2019; Uppsala University's Gotland Campus, Visby; Sweden; 22 May 2019 through 24 May 2019
Note

QC 20191024

Available from: 2019-10-24 Created: 2019-10-24 Last updated: 2019-10-24Bibliographically approved
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