Final report for WP4.3: Enhancement of design methods ... - Upwind

3.2 Comparison of deterministic load cases
Deterministic load cases have been defined to compare the results on the level of time series. The load
cases have increasing complexity. Aerodynamic loading and hydrodynamic loading have been simulated
separately, followed by combined loading. The course of oscillation and amplitudes of the time series is
very equal in all analysed cases. Simulations have been carried out with a constant wind speed of 8m/s
and an aligned extreme stream function wave of 8m wave height and a wave period of 10s. Table 3.2
gives an overview of the three simulated cases.
Load
case
Table 3.2: Simulated load cases for code-to-code comparison
Description Wind conditions Wave conditions Directionality
1.1 Just wind, still water Constant, 8m/s Still water Wind from North (0°)
1.2 Just waves, no wind No wind Stream function with H=8m and
2.1 OWT operating with
wind and waves
18
T=10s
Constant, 8m/s Stream function with H=8m and
T=10s
Waves from North (0°)
Wind and waves co-linear
from North (0°)
Overall seven sensors (load effects) have been selected for the reference validation. Four of them are
located in the jacket. Figure 3.2 shows the position of the jacket sensors. The remaining three sensors are
the rotor speed, electrical power output and the out-of-plane bending moments of blade number one. The
wind turbine is pointing in the negative direction of the global x-axis in the picture.
wind / waves
#3
#2
2
4
Figure 3.2: Position of sensors at the reference jacket
Exemplarily the time series of the combined wind and wave case (case 2.1) for the turbine sensors is
shown in Figure 3.3. The curves show good agreement, even if some small differences in rotor speed and
power output are visible. This is due to differences in the power loss definition and power controller implementations.
Still, the differences are marginal and the resulting out-of-plane bending moment of blade
one gives a good agreement.
1
#1
3
y
#4
z
x