Open AccessMeasurement of spectra over the Bolund hill in wind tunnel
Author(s) -
CuervaTejero Alvaro,
AvilaSánchez Sergio,
GallegoCastillo Cristóbal,
LópezGarcía Óscar,
PérezAlvarez Javier,
Yeow Tee Seong
Publication year - 2018
Publication title -
wind energy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.743
H-Index - 92
eISSN - 1099-1824
pISSN - 1095-4244
DOI - 10.1002/we.2146
Subject(s) - wind tunnel , spectral line , reynolds number , physics , particle image velocimetry , geometry , spectral density , anemometer , boundary layer , mechanics , wind speed , geology , optics , meteorology , mathematics , turbulence , astronomy , statistics
Abstract We have determined the normal Reynolds stresses and spectra of the wind velocity over a 1:115 scale mock‐up of the Bolund hill. The experiment was run in a neutral boundary layer wind tunnel using 3‐component hot‐wire velocimetry, 2‐component particle image velocimetry, and a high‐precision traversing system. Spectra have been determined at different points along transects at 2 and 5 m height above ground level. The experiment was run for 270° wind direction and for two Reynolds numbers,Reh 1= 4 . 25 × 1 0 4 andReh 2= 8 . 21 × 1 0 4 , based on the maximum height of the hill and the free wind speed at this height. Our results show how the normalized power spectral densityS i i σ = f S i i /u i 2 ‾ changes over the hill. The analysis of the normalized streamwise spectrum at 2 m height, just after the escarpment, reveals that part of the energy is concentrated in the interval of normalized frequencies n h ≈0.01−0.02, which could be a signature of a weakened “flapping” phenomenon described in the literature for flows over forward facing steps. The departure of the spectra slope in the inertial subrange, from the value −5/3, was found to be correlated with the hill geometry.