OC4 Phase I load case 1.0b
1 Test description
In this load case, we compare the eigenfrequencies of the OC4 Phase I model between Ashes and the participants of the project. The data from the participants can be seen in figure 4 from
2 Model
The mode is the NREL 5-MW reference wind turbine mounted on the OC4 Jacket, as defined in
It can be recreated using the offshore template and using the CSV file available here.
3 Results
The eigenfrequences of the model are solved and compared to those presented in the OC4 Phase I project. Note that the numbering of the eigenfrequencies in Ashes is from the lowest frequency to the highest, which is not the same as in the OC4 Phase I project. The table below summarises the numbering correspondance.
| Mode number in Ashes | Mode name | Mode number in OC4 Phase I |
| 1 | 1st global side-to-side | 2 |
| 2 | 1st global fore-aft | 1 |
| 3 | 1st drivetrain torsion | 3 |
| 4 | 1st asymetric flapwise yaw | 5 |
| 5 | 1st asymetric flapwise pitch | 4 |
| 6 | 1st flapwise collective | 6 |
| 7 | 1st asymetric edgewise yaw | 8 |
| 8 | 1st asymetric edgewise pitch | 7 |
| 9 | 2nd global fore-aft | 10 |
| 10 | 2nd glbal side-to-side | 11 |
| 11 | 2nd asymetric flapwise yaw | 12 |
| 12 | 2nd asymetric flapwise pitch | 13 |
| 13 | 2nd flapwise collective | 14 |
| 14 | 1st edgewise collective | 16 |
| 15 | 1st global torsion | 15 |
A bar plot with the eigenfrequencies from the different participants in the OC3 Phase II project and from Ashes is available on the following link.
Note that only a visual check is performed in that report. Once we have a set of results that are in agreement with the other participants, we use that set as a base case to compare the results produced by Ashes daily. If these results differ from more than 0.01% with the base, a failed test notification is raised. The report can be found on the following link: