ABSTRACT

Floating offshore wind platforms with circular hulls are well-known worldwide. This study investigated the diffraction analysis of a 5MW NREL wind turbine supported by circular and elliptical hulls with aspect ratios of 1, 1.5, 2, and 2.5 using ANSYS-AQWA. Results showed a significant decrease in added mass with increasing aspect ratios, while heave radiation damping remained unaffected. Maximum diffraction and Froude-Krylov (F-K) forces occurred at aspect ratios of 1 and 1.5, and minimum forces at aspect ratios of 2 and 2.5. These findings highlight the crucial role of hull geometry in reducing wave-induced loads.

INTRODUCTION

In the current scenario, the importance of renewable energy increases due to the scarcity of conventional energy resources, and offshore renewable energy sources play an essential role. The offshore floating wind turbines contribute significantly to energy generation, among other offshore renewable energy resources (Campanile et al., 2018). In general, offshore floating platforms are a combination of wind turbine generators, different kinds of floating platforms, and the station keeping systems (moorings and tethers) (Jonkman, 2010; Clement et al., 2021) The floating offshore wind platforms are more viable for deeper water depths with deep drafts due to the more stable nature (Nielsen et al., 2006). The first conceptual design of a spar-type floating wind turbine was developed for 100 m to 300 m water depths. It highlighted the economic and technical aspects of installing the offshore wind farm based on the FLOAT concept (Tong, 1998). Since then, the investigations have expedited towards the generation of offshore wind renewable energy with different floating platforms, and among them, the deep draft conventional circular hull spar platforms have been well established in the recent past (Moriya et al., 2007; Leroy et al., 2022; Li et al., 2024). Yue et al. (2020) conducted the numerical analysis using AQWA on the wind turbine supporting a circular spar platform with and without heave plates and concluded that the influence of surge response is insignificant, and the heave response is significant when using heave plates. Further, the researchers conducted experimental and numerical studies on the floating offshore wind turbines with circular hull spar platforms under wind, currents and waves and derived the spar-type floating wind turbine guidelines (Rahmdel et al., 2016).

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