Final report for WP4.3: Enhancement of design methods ... - Upwind
Final report for WP4.3: Enhancement of design methods ... - Upwind
Final report for WP4.3: Enhancement of design methods ... - Upwind
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UPWIND WP4: Offshore Support Structures and Foundations<br />
unrestrained motion (surge) [m]<br />
4<br />
3<br />
2<br />
1<br />
0<br />
-1<br />
-2<br />
-3<br />
-4<br />
0 20 40 60<br />
Time [s]<br />
80 100 120<br />
unrestrained motion (heave) [m]<br />
1.5<br />
1<br />
0.5<br />
0<br />
-0.5<br />
-1<br />
-1.5<br />
0 20 40 60<br />
Time [s]<br />
80 100 120<br />
109<br />
unrestrained motion (pitch) [deg]<br />
15<br />
10<br />
5<br />
0<br />
-5<br />
-10<br />
-15<br />
0 20 40 60<br />
Time [s]<br />
80 100 120<br />
Figure 8.20: First and second-order unrestrained motions in surge, heave and pitch modes <strong>for</strong> the OC3-Hywind <strong>for</strong> a Pierson-Moskowitz<br />
spectrum with Hs=5.0 m (Tp=11.18 s).<br />
Semi-submersible results<br />
Linear hydrodynamic loads and unrestrained motions<br />
The frequency dependence <strong>of</strong> the linear excitation <strong>for</strong>ces and moments are shown in Figure 8.21 <strong>for</strong> incident<br />
wave periods up to 25s. These are computed at the centre <strong>of</strong> mass <strong>of</strong> the structure and given as nondimensional.<br />
|F |<br />
X1<br />
|F |<br />
X2<br />
|F |<br />
X3<br />
400<br />
200<br />
0<br />
0 10 20<br />
Wave Period [s]<br />
50<br />
0<br />
0 10 20<br />
Wave Period [s]<br />
200<br />
100<br />
0<br />
0 10 20<br />
Wave Period [s]<br />
[deg]<br />
Phase F X1<br />
[deg]<br />
Phase F X2<br />
[deg]<br />
Phase F X3<br />
500<br />
0<br />
-500<br />
0 10 20<br />
Wave Period [s]<br />
5000<br />
0<br />
-5000<br />
0 10 20<br />
Wave Period [s]<br />
500<br />
0<br />
-500<br />
0 10 20<br />
Wave Period [s]<br />
|F |<br />
X4<br />
|F |<br />
X5<br />
|F |<br />
X6<br />
2000<br />
1000<br />
0<br />
0 10 20<br />
Wave Period [s]<br />
4000<br />
2000<br />
0<br />
0 10 20<br />
Wave Period [s]<br />
x 104<br />
2<br />
1<br />
0<br />
0 10 20<br />
Wave Period [s]<br />
[deg]<br />
Phase F X4<br />
[deg]<br />
Phase F X5<br />
[deg]<br />
Phase F X6<br />
200<br />
0<br />
-200<br />
0 10 20<br />
Wave Period [s]<br />
200<br />
0<br />
-200<br />
0 10 20<br />
Wave Period [s]<br />
200<br />
0<br />
-200<br />
0 10 20<br />
Wave Period [s]<br />
Figure 8.21: Excitation <strong>for</strong>ces and moments in surge (1), sway (2), heave (3), roll (4), pitch (5) and yaw (6) <strong>for</strong> the semisubmersible<br />
plat<strong>for</strong>m <strong>for</strong> incident wave periods up to 25 s.<br />
The frequency dependence <strong>of</strong> the non-dimensional added-mass and damping coefficients is shown in Figure<br />
8.22. Taking into account the symmetry <strong>of</strong> the hydrodynamic coefficients and the geometry <strong>of</strong> the semisubmersible<br />
plat<strong>for</strong>m only six coefficients shown are <strong>of</strong> interest. The coefficients in surge and sway are equal<br />
and also in roll and pitch. All crossed terms are negligible except the surge-pitch and sway-roll. <strong>Final</strong>ly, the nondimensional<br />
hydrostatic coefficients computed <strong>for</strong> the semi-submersible plat<strong>for</strong>m are shown in Table 8.17.
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