Task 30 –
OC4 Phase I:
Jacket support structure
Activity during OC3, Phase III focused on a multi-braced steel support structure, and the participants in OC4 build on those findings. Attention is given to aspects such as the buoyancy calculation and methods of accounting for additional masses (such as hydrodynamic added mass). Also, investigation of local modes and dynamics of a jacket is in the scope of interest.. This work is useful to industry because jackets are increasingly used in and suggested for wind power facilities—e.g., the recently completed wind park “alpha ventus” in the German portion of the North Sea—and for several proposed projects in the United States.
Furthermore, precise model input and boundary conditions are available:
- The NREL 5-MW reference wind turbine is publicly available. It was used in the final stages of OC3 and in several international research projects, such as UpWind (European FP6).
- A jacket support structure has been specifically designed to support the NREL reference turbine by Rambøll as part of Work Package 4 of the UpWind project. As of September 17, 2009, Rambøll has kindly agreed to make the jacket available to OC4 participants. Fraunhofer IWES and the Endowed Chair of Wind Energy (SWE) at Stuttgart University made the corresponding design basis available as well.
Figure 1 Description of Phase I Jacket Support Structure
A set of load cases of increasing complexity is supplied to participants. The simulation results are consolidated by Fraunhofer IWES and made available for further analysis. Confidentiality is minimal to allow new partners to easily join before and during the project. Participants may compare the design basis and results with their own code after the project is completed. This is ensured by choosing publicly available jacket and turbine designs to be used by all the participants.
Phase I is already completed and its results are published in Proceedings of the 22nd International Ocean and Polar Engineering Conference (ISOPE). The results already obtained within Phase I received the international recognition in the academic and industrial sectors.