ABSTRACT In this paper, a numerical tool (MicroSAS-OWT) for the integrated analysis of Offshore Wind Turbines (OWTs) with fixed-bottom support structure of arbitrary shape is presented. MicroSAS-OWT is developed through the coupling of FAST with MicroSAS. FAST is used for modeling the rotor nacelle assembly, while the tower and the support structure are modeled in MicroSAS. The interface of the two codes is ensured at the tower top. The tool is applied for the case of the NREL 5MW OWT that consists of a monopile support structure with rigid foundation, and is preliminary assessed through comparison of results with the corresponding ones obtained using FAST. Stress analysis of the tower and the support structure is also performed.
INTRODUCTION Offshore wind energy represents a very promising kind of renewable energy source. Offshore Wind Turbines (OWTs) are considered nowadays as an attractive alternative solution to the onshore ones offering multiple benefits and addressing effectively the well-known obstacles and problems associated with the latter ones (Henderson et al., 2003; Breton and Moe, 2009; Esteban et al., 2011). The efficient exploitation of offshore wind energy necessitates the successful handling of several challenges related to developmental, economical and technological issues (Musial et al., 2006). Among these challenges, one of the most crucial is the development, investigation, assessment and adoption of new design concepts, especially for the support structure. These new design concepts will allow the placement of OWTs in deeper water and therefore, the operation of larger capacity OWTs. Considering the high complexity characterizing any OWT system, resulting from its inherent characteristics (e.g. variability and intense interaction of components) and from its operation in a complex environment, where different loading sources exist, the development/application of suitable numerical tools is critical for addressing efficiently the previously mentioned challenge.