Shi, Wei (Dalian University of Technology) | Tan, Xiang (Nanyang Technological University) | Zhou, Li (Jiangsu University of Science and Technology) | Ning, Dezhi (Dalian University of Technology) | Karimirad, Madjid (Queen's University)
The ice loading process has a clear stochastic nature due to variations in the ice conditions and in the ice-structure interaction processes of offshore wind turbine. In this paper, a numerical method was applied to simulate a monopile fixed-bottom and a spar-type floating wind turbine in either uniform or randomly varying ice conditions, where the thickness of the ice encountered by the spar were assumed to be constant or randomly generated. A theoretical distribution of the ice thickness based on the existing measurements reported in various literatures was formulated to investigate the response characteristics of the monopile wind turbine and spar wind turbine in such ice conditions. The effect of the coupling between the ice-induced and aerodynamic loads and responses for both operational and parked conditions of the rotor was studied. Moreover, the dynamic response of wind turbine in randomly varying ice was compared and verified with that of the wind turbine in constant ice.
So far, more than 80% of the energy all over the world comes from fossil fuels. Excessive and improper use of fossil fuels has caused climate change and threatened human security and development. The Paris Agreement, which entered into force on 4 November, 2016, is a major step forward in the fight against global warming. Due to severe smog, forty Chinese cities reel under heavy air pollution. Air pollution becomes one of the key words in China in 2016 (PTI, 2016). Renewable energies play an important role for reducing greenhouse gas emissions, and thus in mitigating climate change. Offshore wind energy is recognized as one of the world's fastest growing renewable energy resources. By the end of 2015, totally 12,107 MW of offshore wind energy was installed around the world according to Global Wind Energy Council (GWEC) report (Fried, 2016). In Europe, 3230 turbines are now installed and grid-connected, making a cumulative total of 11,027 MW (Ho, 2016). However, governments outside of Europe have set ambitious targets for offshore wind and development is starting to take off in China, Japan, South Korea and the US. The 1.2 GW of capacity installed in Asia as of the end of 2015 was located China and mainly in Japan.
Bonnemaire, Basile (Multiconsult AS;) | Tan, Xiang (Multiconsult AS;) | Serré, Nicolas (Multiconsult AS;) | Fredriksen, Arnt (Multiconsult AS;) | Metrikin, Ivan (Statoil ASA) | Gürtner, Arne (Statoil ASA)
Interaction between a moored structure and drifting broken ice is a complex process. To document the expected structure response, ice basin tests of the interaction are common practice. The outcomes of ice basin tests need to be carefully analyzed before extrapolation to expected full-scale target responses. The preferred strategy is to use numerical simulations to correct the measurements. The numerical model needs to be qualified by successful post-simulations of the achieved ice basin interactions.
Post-simulations of interactions between drifting broken ice and a moored floating structure are of high complexity. The response of both the structure and the ice field needs to be replicated. This requires a good modeling of the ice field properties that matter (such as the floe size distributions and concentrations) and the boundary conditions affecting the interactions (such as the effect of the ice basin walls).
Statoil's SIBIS numerical model is used to post-simulate ice basin tests of the moored Cat-I drillship. The present paper discusses the challenges with such post-simulations and presents the philosophy chosen for achieving successful postsimulations.