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means along the section SE-NE until western model edge UG5 has a wake of
135 km, UG8 of 127 km, and UG16 of 125 km.
Besides wind speeds, also OWF conditions like the amount of wind turbines and
the area being occupied can influence the magnitude of the OWF-induced wind wake.
4.2.2.3 Analysis of Different Wind Farms
Considering political aims, OWFs will be much greater than the used arrangement
of 12 turbines within 4 grid boxes. This section shows how the wind wake will
change due to different amounts of wind turbines, including 12 (T012), 48 (T048),
80 (T080), and 160 (T160) wind turbines (Table 4.2 ).
As mentioned, the wind farm constructions follow the rules of energy produc-
tion. Due to the fact that each wind turbine produces a wake behind itself, the
minimum recommended distances exist between them. Therefore, to be realistic, it
is unfeasible to analyze different amounts of wind turbines within the four grid cells
used before because an amount of 160 turbines cannot be placed in 4 grid boxes.
That complicates a comparison of OWF wakes related to wind turbines. Neverthe-
less, keeping a quadratic form close to the middle of the model area elects the
arrangement. Arrangement of wind turbines over the model area is shown in
Fig. 4.5 a1-a4. The prescribed geostrophic wind is ug
¼
8 m/s for all four wind
turbine cases.
The 10-m horizontal wind fields for T012, T048, T080, and T160 are pictured in
Fig. 4.5 . The common change of the wind field is independent of the amount of
wind turbines - in all cases a surge zone, the two flanks and the wake occurs.
Logically linked to the occupied area by wind turbines, the dimension of the wind
wakes varies. However, the range of changes in wind speed is close with a maximal
reduction of 80 % for T160, 72 % for T012 and T048, and 68 % for T080; see
Table 4.2 . Spanning the wind turbines over more grid boxes intensifies the wake in
magnitude and dimension.
Here, the wind turbines are distributed along y -direction, almost across wind
direction, which defines the wake area.
Comparing OWFs of T012 and T048, they do not show obvious differences
(Fig. 4.5 ), and these points to the fact that the distribution of wind turbines plays
here a more important factor than the amount of turbines. A four times stronger
wind farm, related to wind turbines, does not lead to a stronger wind wake. Here,
the minima are the same (1.72 m/s) and the maxima slightly differ by only 0.02 m/s.
Figure 4.6 shows the relation between the amount of wind turbines, respectively
OWF grid cells, and the wind speed based on overall extrema in 10-m heights. T012
and T048 have greater maxima compared to T160 and T080. T080 has a character
of an outlayer. The wake in T080 is with 1.93 m/s the strongest, and the maximal
wind speed of 6.24 m/s is the lowest. In this connection, the area in front of the wind
farm T080 (between
30 km) tends to the smallest mean
wind speed of 5.76 m/s compared to T012, T048 and T160. In the case of T160, the
mean wind speed in front of the OWF is 5.94 m/s and even smaller as in the case of
120 km and
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