Browsing by Author "Sai, K.C."

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    Motion response analysis of floating wind turbine combined with wave energy converter
    (Springer, 2020) Sai, K.C.; Patil, A.H.; Karmakar, D.
    The concept of extracting wave energy using wave energy converters (WEC) and wind energy using offshore wind turbines involves high cost of installing and maintenance. To reduce the economic value of the overall project by sharing mooring systems, electrical cables and better use of ocean area, the concept of combining wind turbine with a WEC has come into existence. Using the combined concept of wave and wind energy device, not only the overall project cost reduces but also the power production increases. The present study deals with the coupled dynamic analysis of 5MW offshore floating wind turbine combined with wave energy converter system to study the motion behaviour of combined energy concept under operational conditions using time domain aero-servo-hydro-elastic simulation along with the wave load response analysis. The responses in all 6-DoF are predicted, compared and analysed for different wind speed and wave height. The platform forces and moments are also obtained and the transfer functions for these responses are evaluated using aero-servo-hydro-elastic simulation. Further, a brief comparative study of different combined energy models are performed in details. © Springer Nature Singapore Pte Ltd. 2020.
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    Numerical investigation of offshore wind turbine combined with wave energy converter
    (Springer Nature, 2023) Rony, J.S.; Sai, K.C.; Karmakar, D.
    The coupled dynamic analysis is performed for three different types of offshore floating platforms combined with a wave energy converter (WEC) mounting a 5-MW NREL (National Renewable Energy Laboratory) wind turbine. The Response Amplitude Operators (RAOs) are analysed for the three concepts of combined wind and wave energy platforms for different wind and wave conditions. The hydrodynamic performance for the three different platforms is conducted considering different load cases. The time domain aero-servo-hydro-elastic tool is used to study the motion responses of the combined system under real operational conditions. The platform’s responses are observed to increase with the increase in the wind speed. In the case of floating hybrid platform, surge responses are minimal for the hybrid spar-tours combination for any load case condition. Minimum surge and sway ensure higher wind power absorption. The study further focuses on the tower base forces and moments to study the impact of wind and waves on the combined floater. Fore-aft shear forces and fore-aft bending moments are higher for the platforms indicating the importance of wind-wave loading. The time domain responses are further used as the transfer function to predict the most probable maximum values of motion amplitude expected to occur during the life-time of the structure which can be used for designing a floating wind turbine (FWT) against overturning in high waves. The long-term models are constructed using various short-term situations expected to occur during the structure’s life-time and weighing them appropriately. The long-term distribution uses North Atlantic wave data, and short-term responses are calculated considering Rayleigh distribution. A brief comparative study of the three combined offshore floaters is performed to understand the structural integrity, power performance and dynamic motions of the floating wind energy platform combined with WECs. © 2023, The Author(s), under exclusive licence to Sociedade Brasileira de Engenharia Naval.