Effects of Freestream Turbulence in a Model Wind Turbine Wake

Yaqing Jin, Huiwen Liu, Rajan Aggarwal, Arvind Singh and Leonardo P. Chamorro
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Yaqing Jin: Mechanical Science and Engineering, University of Illinois, Urbana, IL 61801, USA
Huiwen Liu: College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210024, China
Rajan Aggarwal: Mechanical Science and Engineering, University of Illinois, Urbana, IL 61801, USA
Arvind Singh: Civil, Environmental, and Construction Engineering, University of Central Florida, Orlando, FL 32816, USA
Leonardo P. Chamorro: Mechanical Science and Engineering, University of Illinois, Urbana, IL 61801, USA

Energies, 2016, vol. 9, issue 10, 1-12

Abstract: The flow structure in the wake of a model wind turbine is explored under negligible and high turbulence in the freestream region of a wind tunnel at R e ? 7 × 10 4 . Attention is placed on the evolution of the integral scale and the contribution of the large-scale motions from the background flow. Hotwire anemometry was used to obtain the streamwise velocity at various streamwise and spanwise locations. The pre-multiplied spectral difference of the velocity fluctuations between the two cases shows a significant energy contribution from the background turbulence on scales larger than the rotor diameter. The integral scale along the rotor axis is found to grow linearly with distance, independent of the incoming turbulence levels. This scale appears to reach that of the incoming flow in the high turbulence case at x / d ? 35–40. The energy contribution from the turbine to the large-scale flow structures in the low turbulence case increases monotonically with distance. Its growth rate is reduced past x / d ? 6–7. There, motions larger than the rotor contribute ? 50 % of the total energy, suggesting that the population of large-scale motions is more intense in the intermediate field. In contrast, the wake in the high incoming turbulence is quickly populated with large-scale motions and plateau at x / d ? 3 .

Keywords: integral length scale; wake; wind turbine; large-scale motions (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2016
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (20)

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