Abstract
Flow structures in the wake of a wind turbine are analysed by performing spatio-temporal Koopman decomposition (STKD). STKD is a new method to decompose the flow field as a combination of travelling waves and to extract the frequency and wavenumbers (characterizing a specific spatial direction) of the dominant waves. The results indicate that the complex unsteady behaviour of the turbine wake flow is mainly driven by a single wave travelling downstream, combined with smaller amplitude traveling waves representing the flow rotation. This result agrees with the general description of the wake of a wind turbine regarded as the combination of self-sustained oscillations and the development of upstream external noise, which are represented by the dominant traveling wave and the small-magnitude ones, respectively.
Original language | English |
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Pages (from-to) | 922-931 |
Number of pages | 10 |
Journal | Wind Energy |
Volume | 22 |
Issue number | 7 |
DOIs | |
Publication status | Published - Jul 2019 |
Externally published | Yes |
Keywords
- DMD
- HODMD
- Koopman modes
- STKD
- flow structures
- wind turbines