Turbulent Flow Properties Around a Staggered Wind Farm

Leonardo Patricio Chamorro Chavez, R. E.A. Arndt, Fotis Sotiropoulos

Research output: Contribution to journalArticle

Abstract

The fundamental properties of turbulent flow around a perfectly staggered wind farm are investigated in a wind tunnel. The wind farm consisted of a series of 10 rows by 2-3 columns of miniature wind turbines spaced 5 and 4 rotor diameters in the streamwise and spanwise directions respectively. It was placed in a boundary-layer flow developed over a smooth surface under thermally neutral conditions. Cross-wire anemometry was used to obtain high resolution measurements of streamwise and vertical velocity components at various locations within and above the wind farm. The results show that the staggered configuration is more efficient in terms of momentum transfer from the background flow to the turbines compared to the case of an aligned wind turbine array under similar turbine separations in the streamwise and spanwise directions. This leads to improved power output of the overall wind farm. A simplified analysis suggests that the difference in power output between the two configurations is on the order of 10%. The maximum levels of turbulence intensity in the staggered wind farm were found to be very similar to that observed in the wake of a single wind turbine, differing substantially with that observed in an aligned configuration with similar spacing. The dramatic changes in momentum and turbulence characteristics in the two configurations show the importance of turbine layout in engineering design. Lateral homogenization of the turbulence statistics above the wind farm allows for the development of simple parametrizations for the adjustment of flow properties, similar to the case of a surface roughness transition. The development of an internal boundary layer was observed at the upper edge of the wind farm within which the flow statistics are affected by the superposition of the ambient flow and the flow disturbance induced by the wind turbines. The adjustment of the flow in this layer is much slower in the staggered situation (with respect to its aligned counterpart), implying a change in the momentum/power available at turbine locations. Additionally, power spectra of the streamwise and vertical velocity components indicate that the signature of each turbine-tip vortex structure persists to locations deep within the wind farm.

Original languageEnglish (US)
Pages (from-to)349-367
Number of pages19
JournalBoundary-Layer Meteorology
Volume141
Issue number3
DOIs
StatePublished - Dec 1 2011
Externally publishedYes

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wind farm
turbulent flow
turbine
wind turbine
turbulence
momentum
boundary layer
momentum transfer
wind tunnel
surface roughness
vortex
spacing
disturbance
engineering

Keywords

  • Atmospheric boundary layer
  • Staggered wind farm
  • Turbulence
  • Wind-tunnel experiment
  • Wind-turbine wake

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Turbulent Flow Properties Around a Staggered Wind Farm. / Chamorro Chavez, Leonardo Patricio; Arndt, R. E.A.; Sotiropoulos, Fotis.

In: Boundary-Layer Meteorology, Vol. 141, No. 3, 01.12.2011, p. 349-367.

Research output: Contribution to journalArticle

Chamorro Chavez, Leonardo Patricio ; Arndt, R. E.A. ; Sotiropoulos, Fotis. / Turbulent Flow Properties Around a Staggered Wind Farm. In: Boundary-Layer Meteorology. 2011 ; Vol. 141, No. 3. pp. 349-367.
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