Verification of New Floating Capabilities in FAST v8: Preprint
In the latest release of NREL's wind turbine aero-hydro-servo-elastic simulation software, FAST v8, several new capabilities and major changes were introduced. FAST has been significantly altered to improve the simulator's modularity and to include new functionalities in the form of modules in the FAST v8 framework. This paper is focused on the improvements made for the modeling of floating offshore wind systems. The most significant change was to the hydrodynamic load calculation algorithms, which are embedded in the HydroDyn module. HydroDyn is now capable of applying strip-theory (via an extension of Morison's equation) at the member level for user-defined geometries. Users may now use a strip-theory-only approach for applying the hydrodynamic loads, as well as the previous potential-flow (radiation/diffraction) approach and a hybrid combination of both methods (radiation/diffraction and the drag component of Morison's equation). Second-order hydrodynamic implementations in both the wave kinematics used by the strip-theory solution and the wave-excitation loads in the potential-flow solution were also added to HydroDyn. The new floating capabilities were verified through a direct code-to-code comparison. We conducted a series of simulations of the International Energy Agency Wind Task 30 Offshore Code Comparison Collaboration Continuation (OC4) floating semisubmersible model and compared the wind turbine response predicted by FAST v8, the corresponding FAST v7 results, and results from other participants in the OC4 project. We found good agreement between FAST v7 and FAST v8 when using the linear radiation/diffraction modeling approach. The strip-theory-based approach inherently differs from the radiation/diffraction approach used in FAST v7 and we identified and characterized the differences. Enabling the second-order effects significantly improved the agreement between FAST v8 and the other OC4 participants.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy Wind Power Technologies Office
- DOE Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1167453
- Report Number(s):
- NREL/CP-5000-63116
- Resource Relation:
- Conference: To be presented at AIAA SciTech 2015, 5-9 January 2015, Kissimmee, Florida
- Country of Publication:
- United States
- Language:
- English
Similar Records
Comparison of Hydrodynamic Load Predictions Between Engineering Models and Computational Fluid Dynamics for the OC4-DeepCwind Semi-Submersible: Preprint
Offshore Code Comparison Collaboration, Continuation within IEA Wind Task 30: Phase II Results Regarding a Floating Semisubmersible Wind System: Preprint