Effects of freestream turbulence in a model wind turbine wake

Yaqing Jin, Huiwen Liu, Rajan Aggarwal, Arvind Singh, Leonardo P. Chamorro

Research output: Contribution to journalArticle

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 Re ∼ 7 × 104. 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.

Original languageEnglish (US)
Article number830
JournalEnergies
Volume9
Issue number10
DOIs
StatePublished - Oct 2016

Keywords

  • Integral length scale
  • Large-scale motions
  • Wake
  • Wind turbine

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Energy (miscellaneous)
  • Control and Optimization
  • Electrical and Electronic Engineering

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