Welcome to Task 30 –
OC4 (Phase I):
Jacket code comparison
Activity during OC3, Phase III focused on a multi-braced steel support structure, and the participants in OC4 will build on those findings. They will look more closely at member overlap, beam formulation and buoyancy calculation. They may apply new features such as sub structured analysis that have been introduced since Phase III was completed. They will investigate interesting characteristics of jackets such as local modes and dynamics. This work will be useful to industry because jackets are increasingly used in or 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 now 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 OC3/OC4 participants. The Endowed Chair of Wind Energy (SWE) at Stuttgart University made the corresponding design basis available as well.
The OC4 collaboration on jacket-based code comparison will continue and enhance co-operation among organizations.
Figure 1 Description of Phase I Jacket Support Structure
Fraunhofer IWES within the Fraunhofer Society (Fraunhofer-Gesellschaft) takes the lead on Phase I, the jacket code comparison exercise. The Fraunhofer Society is a non-profit organization dedicated to applied research, maintaining 59 institutes with about 17,000 staff in Germany. Fraunhofer IWES is the main center for wind energy research in the Fraunhofer Society and in Germany with 250 staff at two main locations. It also maintains research groups at four German universities. The twelve researchers in the Simulation and Assessment of Wind Turbines Department comprise one of nine research groups working at Fraunhofer IWES. At IWES fully coupled wind turbine simulation tools are developed and used both in house and with industrial partners; IWES contributed to OC3 Phase III.
The aim of OC4 Phase I is not only to benchmark and validate simulation codes on a jacket support structure, but also to encourage model and tool development and the training of new analysts.
A set of load cases of increasing complexity will be supplied to participants. The simulation results will be consolidated by Fraunhofer IWES and made available for further analysis. Regular meetings and publications are planned. Confidentiality will be 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 will be ensured by choosing publicly available jacket and turbine designs to be used by all the participants.
