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

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UPWIND WP4: Offshore Support Structures and Foundations A 11 A 44 10000 A 15 5000 0 0 10 20 Wave Period [s] x 106 7.6 7.4 7.2 0 10 20 Wave Period [s] x 104 2 0 -2 0 10 20 Wave Period [s] A 33 A 66 A 24 x 104 1.35 1.3 1.25 0 10 20 Wave Period [s] x 106 10 5 0 0 10 20 Wave Period [s] x 104 2 0 -2 0 10 20 Wave Period [s] 110 B 11 B 44 B 15 4000 2000 0 0 5 10 15 20 25 Wave Period [s] x 105 2 1 0 0 5 10 15 20 25 Wave Period [s] x 104 2 0 -2 0 5 10 15 20 25 Wave Period [s] B 33 B 66 B 24 100 50 0 0 5 10 15 20 25 Wave Period [s] x 106 5 0 0 5 10 15 20 25 Wave Period [s] x 104 2 0 -2 0 5 10 15 20 25 Wave Period [s] Figure 8.22: Added-mass and hydrodynamic damping coefficients for the semi-submersible platform for incident wave periods up to 25 s Table 8.17: Non-dimensional hydrostatic coefficients for the semi-submersible platform. Coefficient Value Coefficient Value C33 269.76 C45 0.13018E-01 C34 -0.16089E-02 C46 0.13611 C35 -0.14339E-02 C55 0.14636E+06 C44 0.14636E+06 C56 -0.70826E-01 The frequency dependence of the response amplitude operator (RAO) for the unrestrained motions of the semi-submersible platform is shown in Figure 8.23. For this structure, resonance occurs in heave for the unrestrained submerged motions at about 17 s. At this wave period the motions in surge, roll and pitch have also maximum amplitude. |X 1 | |X 2 | |X 3 | 1 0.5 0.04 0.02 0 0 5 10 15 20 25 Wave Period [s] 0 0 5 10 15 20 25 Wave Period [s] 100 50 0 0 5 10 15 20 25 Wave Period [s] Phase X 1 [deg] Phase X 2 [deg] Phase X 3 [deg] 200 0 -200 0 5 10 15 20 25 Wave Period [s] 200 0 -200 0 5 10 15 20 25 Wave Period [s] 200 0 -200 0 5 10 15 20 25 Wave Period [s] |X 4 | |X 6 | |X 5 | 0.04 0.02 0 0 5 10 15 20 25 Wave Period [s] 0.4 0.2 0 0 5 10 15 20 25 Wave Period [s] 0.01 0.005 0 0 5 10 15 20 25 Wave Period [s] Phase X 4 [deg] Phase X 5 [deg] Phase X 6 [deg] 200 0 -200 0 5 10 15 20 25 Wave Period [s] 200 0 -200 0 5 10 15 20 25 Wave Period [s] 200 0 -200 0 5 10 15 20 25 Wave Period [s] Figure 8.23: Frequency dependence of the response amplitude operator (RAO) for the linear unrestrained motions in surge (x1), sway (x2), heave (x3), roll (x4), pitch (x5) and yaw (x6) associated with the semi-submersible platform. Second-order hydrodynamic loads and unrestrained motions for monochromatic waves Given the input wave spectrum represented by N components, the time-series of the total excitation force is computed as for the OC3-Hywind platform. The second-order solution requires the additional discretisation of the free-surface. This mesh is shown in Figure 8.24 for the semi-submersible platform.
UPWIND WP4: Offshore Support Structures and Foundations Figure 8.24: Mesh used to discretise the free-surface for the computation of the second-order hydrodynamic quantities for the semi-submersible platform. This section presents the results for monochromatic, head-on waves for the same wave periods and heights listed in Table 8.13. For a monochromatic wave, the second-order excitation force is given by Equation 3-11. The non-dimensional values of the sum- and difference- force QTFs for the three monochromatic wave periods considered in the present study are given in Table 8.18. The first-order excitation forces are also given for comparison in Table 8.19 for the same modes and wave periods. The sum- frequency components of the force QTFs (f+) are higher than the difference- frequency components (f-) for all modes and monochromatic waves. Table 8.18: Non-dimensional sum- and difference- force QTFs at double and zero frequency for surge (1), sway (2), heave(3), roll (4), pitch (5) and yaw (6) modes at three monochromatic wave periods for the semi-submersible platform. T=5 s T=7 s T=9 s Mode Abs. value Phase (deg) Abs. value Phase (deg) Abs. value Phase (deg) f + 1 f 510.29 -66.07 39.16 -176.84 14.93 -51.10 - 12.42 180.00 2.91 180.00 0.83 180.00 f + 2 f 408.46 54.67 23.02 16.40 5.07 -118.96 - 0.16 0.00 0.07 0.00 0.14 180.00 f + 3 f 4.36 -103.79 1.22 -70.50 1.84 29.91 - 0.01 0.00 0.44 0.00 0.55 0.00 f + 4 f 3,966.57 -125.86 202.49 177.28 42.30 123.52 - 6.20 180.00 8.37 0.00 6.58 0.00 f + 5 f 4,968.51 -65.70 373.25 -163.92 81.98 -29.44 - 164.03 -180.00 41.64 -180.00 9.52 -180.00 f + 6 f 10,484.50 -164.69 3,946.98 -145.71 205.89 41.62 - 2.87 0.00 20.27 0.00 10.19 -180.00 Table 8.19: Non-dimensional linear excitation forces for surge (1), sway (2), heave (3), roll (4), pitch (5) and yaw (6) modes at three monochromatic wave periods for the semi-submersible platform. T=5 s T=7 s T=9 s Mode Abs. value Phase (deg) Abs. value Phase (deg) Abs. value Phase (deg) 1 97.7 -131.6 65.5 99.0 169.2 -91.0 2 15.7 -162.0 31.5 157.6 8.2 -85.8 3 13.6 -148.7 14.6 -16.9 44.5 175.5 111
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Project UpWind Contract No.: 019945
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Acknowledgement The presented work
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Summary The overall aim of the UpWi
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Table of Contents Acknowledgement..
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Task 4.1 Integration of support str
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Sequential coupling The sequential
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analysis. In the new multibody code
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Figure 2.4: 2nd global bending mode
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3.2 Comparison of deterministic loa
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Figure 3.5: Time series of axial fo
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• Time domain simulation in ADCoS
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• A supplementary load vector for
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The following results are found: Fi
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Figure 4.5: Output positions in the
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It is directly visible that there i
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ated eigenfrequency is shifted into
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Water levels For the calculation of
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guidelines for the inclusion of cli
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damaging if the frequency of the ex
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uncertain parameters carefully. Thr
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Table 5.3 shows annual reliability
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Steel substructure for offshore win
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Table 5.16 shows the required FDF v
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A Fracture Mechanical (FM) modellin
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Figure 5.4: Annual reliability indi
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Further, the effect of possible ins
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Rainflow evaluation The load cases
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For DLC 7.2 it has to be considered
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Guideline, DLC 1.5). Furthermore, t
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Page 62 and 63: From these results it can be clearl
Page 64 and 65: Figure 5.11: Normalised DELs with v
Page 66 and 67: Figure 5.14 presents normalized DEL
Page 68 and 69: Figure 5.16: Output locations for e
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Final report for WP4.3: Enhancement of design methods ... - Upwind

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