Wind Energy

34 J. Fernández Puga et al.
6.2 Experimental Setup
The measurements have been carried out in the wind tunnel of the University
of Kaiserslautern using the laser Doppler anemometry operating in backscatter
mode. The seeding particles which have a size of 2µm are made by spraying
a solution of glycerine and water.
In order to carry out feasible measurements the experimental setup has
been chosen according to the German VDI-guideline 3783. The boundary layer
has been thickened artificially using spires which were fixed at the entrance of
the test section. The power law exponent of the modelled atmospheric boundary
layer (Fig. 6.1) has a value of 0.16 which corresponds to a moderately
rough terrain according to the guideline.
Furthermore, the turbulence intensities in longitudinal, lateral and vertical
direction (Fig. 6.2) represent also a moderately rough terrain. The spectral
z [mm]
450
400
350
300
250
200
150
100
z [mm]
50
0
0
400
350
300
250
200
150
100
50
0
1 2 3
U [m/s]
4 5
z [mm]
10000
1000
100
10
1
0 1 2 3 4 5 6
0.1
0.01
U [m/s]
Fig. 6.1. Modelled atmospheric boundary layer
0 0.1 0.2 0.3 0.4
Turbulence Intensity Ix
wenig rau / slightly rough
maBig rau / moderately rough
rau / rough
sehr rau / very rough
Fig. 6.2. Turbulence intensity in longitudinal direction
0.5
0.6