Numerical and experimental Sea Ice Loads for Global Dynamics of Offshore Wind Turbines
Project term: 01.04.2016 – 28.02.2019
Funding: German Federal Ministry for Economic Affairs and Energy (www.bmwi.de, 0324022B)
The offshore wind energy sector shows potential in many different regions, for instance the North and Baltic Sea. The German Federal Ministry for Economic Affairs and Energy aims to establish 15 GW of offshore wind energy (OWE) until 2030. The Baltic Sea is particularly interesting for OWE due to good wind conditions and shallow waters. The estimated potential for OWE in the Baltic Sea is about 40 GW, depending on the scenario.
One problem regarding OWE in the Baltic Sea is sea ice, which generally represents a risk to offshore structures, such as offshore wind turbines (OWT). Sea ice is annually present in the northern part of the Baltic Sea, but it may also appear in the southern part with a significant thickness. Firstly, sea ice loads can introduce damage to the structure, for example fatigue failure. Secondly, the interaction between the OWT structure, e.g. a monopile, and the ice may also influence the operation. This makes it necessary to include ice-structure interaction in the design process of wind turbines. Consequently, besides aspects such as wind and waves, dynamic simulations of OWT also need to consider ice loads.
In order to do this, the calculation of possible ice loads is necessary. Different approaches are used, for instance empirical methods, spring-mass-dashpot models or finite-element simulations. However, most of the existing methods are not sufficiently validated and can only give rough estimates. Moreover additional effects are expected when the flexibility of the structure and hence the response to ice loads is included in the simulation, e.g. ice-induced vibration (IIV). The full simulation of ice-structure interaction is only possible with coupled models.
This subproject is part of the project “Impact of Sea Ice Loads on Global Dynamics of Offshore Wind Turbines (SeaLOWT)”. The aim of SeaLOWT is to simulate the dynamic response of offshore wind turbines (OWT) under consideration of sea ice loads. This will be done with three project partners, TUHH, Fraunhofer IWES and Ramboll.
The following tasks are part of the SeaLOWT_NE project:
- Development of a material model which is suitable for ice in the Baltic Sea. Representative volume elements (RVE) will be used to increase the efficiency of the simulation.
- Development of a framework for coupled ice-structure-fluid interaction simulations. This includes a physics engine for the contact dynamics, an FE solver for structure and ice modelling and a GPU CFD solver based on the Lattice Boltzmann method.
- Large scale experiments for ice in compression and bending to validate the coupled simulation and the material model.