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Results
Superelement Approach In Fully Coupled OffshoreWind Turbine Simulation: Influence of the Detailed Support Structure Modelling On Simulation Results For a 5-MW Turbine On a Tripod Substructure
Vorpahl, Fabian R. (Fraunhofer Institute for Wind Energy and Energy System Technology (IWES)) | Strobel, Michael (Fraunhofer Institute for Wind Energy and Energy System Technology (IWES)) | Busmann, Hans-Gerd (Fraunhofer Institute for Wind Energy and Energy System Technology (IWES)) | Kleinhansl, Stefan (Aero Dynamik Consult Ingenieurgesellschaft (ADC))
ABSTRACT Fatigue design and certification of offshore wind turbines (OWT) is performed using aero-servo-hydro-elastic time domain simulations. So far, the local flexibility of the joints in branched OWT support structures has been neglected in those simulations. In this work, a superelement approach, allowing for detailed modeling of local joint flexibility in the OWT design tool ADCoS-Offshore, is presented. The influence of this simulation approach, taking into account joint stiffnesses with the same level of accuracy as detailed finite element models, is described and interpreted using the example of a realistic 5MW OWT on a tripod in 45m of water. Further, recommendations for modeling of turbines on this type of structure are given. INTRODUCTION Growing turbine size and steps towards deeper waters and serial production of support structures are key parameters describing the current offshore wind energy development. Branched bottom mounted support structures such as tripiles1, tripods or jackets2 3 are currently used as prototypes and accepted as promising solution for large scale future projects. To allow for cost effective and reliable design, accurate and confidable simulation of the system offshore wind turbine (OWT) is inevitable. Especially for fatigue simulation and certification, aero-hydro-servoelastic tools are used. A selection of the tools that are currently available is shown by Nichols et al. (2009). For the purpose of this study, a 5-MW OWT on a tripod support structure was implemented in ADCoS-Offshore. This is the aero-servohydro- elastic tool used at Fraunhofer IWES. ADCoS-Offshore is a nonlinear finite element (FE) based tool applying a direct implicit time domain integration scheme. Details on ADCoS-Offshore are provided in Kleinhansl et al. (2004) and Vorpahl et al. (2007). The model in ADCoS-Offshore incorporates deterministic or stochastic wind fields and modified blade-element momentum (BEM) theory for aerodynamic description of the turbine.
- Europe > Germany (0.46)
- Europe > Netherlands (0.28)
Hydrodynamics Meet Wind Turbines: Specification And Development of a Simulation Tool For Floating Wind Turbines With Modelica
Quesnel, Louis (Fraunhofer Institute for Wind Energy and Energy System Technology (IWES)) | Vorpahl, Fabian (Fraunhofer Institute for Wind Energy and Energy System Technology (IWES)) | Strobel, Michael (Fraunhofer Institute for Wind Energy and Energy System Technology (IWES)) | Busmann, Hans-Gerd (Fraunhofer Institute for Wind Energy and Energy System Technology (IWES))
ABSTRACT The research presented in this paper aims at improving hydrodynamics modelling for floating offshore wind turbines, as part of a broader effort to develop a fast, modern, more flexible aero-hydro-servo-elastic simulation tool utilizing state-of-the-art modelling software. A review of floater concepts proposed in recent years leads to the definition of a set of requirements and specifications for a novel hydrodynamics simulation module within the aforementioned tool, including wave and load models and validation. An outline of the entire dynamic simulation tool is presented, which takes advantage of prospects offered by the modelling language Modelica, developed specifically to model large, heterogeneous, complex physical systems. As a first implementation step, the development and validation of the wave kinematics module are detailled together with a benchmark against existing tools. INTRODUCTION Floating offshore wind turbines represent both a great hope for renewable energies due to the great wind energy potential available offshore in deep water areas, and a significant challenge for engineers and scientists. Compared to their oil and gas siblings, those offshore structures are subjected to a remarkably high wind thrust on the rotor, itself located together with the 400+ tons nacelle some 90m above the still water level, resulting in a comparatively high overturning moment as well as aeroelastic and gyroscopic effects. Due to the stochastic nature of wind and wave loads, combined with turbine dynamics inducing high numbers of variable amplitude load cycles (10), fatigue is an important design driver. The 60+m long flexible rotor blades and complex controls lead to non-linear dynamic behaviour in the electro-mechanical system. Furthermore the lower profitability of offshore wind energy projects compared to oil and gas projects puts more pressure on engineers to design light, less-conservative structures subject to high dynamic loads and ensure easy maintenance.
- Asia > Japan (0.28)
- North America > United States (0.28)
- Europe > Germany (0.28)