Faculty Publications
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Publications by NITK Faculty
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Item Coupled dynamic analysis of semi-submersible floating wind turbine integrated with oscillating water column WEC(Springer Science and Business Media Deutschland GmbH, 2024) Sebastian, B.; Karmakar, D.; Rao, M.The present study envisages to investigate the coupled dynamic behaviour of three configurations of a hybrid wind-wave energy system integrating Oscillating Water Column (OWC) wave energy converters to DeepCwind semi-submersible supporting an NREL (National Renewable Energy Laboratory) 5 MW wind turbine. DeepCwind semi-submersible is a platform designed specifically for the purpose of supporting floating offshore wind turbines and the stability of the platform has been well confirmed by scaled-down experiments and numerical studies. The numerical simulation for the present study is performed using the aero-hydro-servo-elastic tool OpenFAST. The dynamic responses of the hybrid platforms are determined for different operational and parked wind speed conditions of the wind turbine in irregular waves. The motion responses, tower base forces and moments, mooring tensions and power absorption of the hybrid configurations have been characterized. Furthermore, the effect of coupling between the semi-submersible platform and the OWCs is studied by comparing the results of the combined platforms with that of the uncoupled wind energy platform. The coupled dynamic analysis in the time domain shows that increasing the number of OWC helps to reduce the motion responses in heave and pitch. The capture width ratio of the system is observed to be highest for hybrid configuration with a single OWC device. The present study will be helpful in the design and analysis of hybrid floating wave-wind energy platform. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.Item Dynamic analysis of a semi-submersible offshore floating wind turbine combined with wave energy converters(Taylor and Francis Ltd., 2025) Sebastian, B.; Karmakar, D.; Rao, M.Hybrid wind–wave energy systems harness both offshore wind and wave energy resources using a shared floating platform, reducing capital and operational costs through common infrastructure. The present study numerically investigates the dynamic performance and power absorption of three hybrid concepts combining the DeepCwind Semi-submersible Platform (SSP) with (i) Oscillating Water Columns (OWC), (ii) Torus Wave Energy Converter (WEC), and (iii) Flap-type WEC. Frequency-domain analyses using WAMIT and time-domain simulations using OpenFAST are performed to assess platform motions, tower base moments, mooring tensions, and WEC power output for different sea states. The integration of WECs significantly improves the hydrodynamic behaviour of the DeepCwind SSP. Flap-type WECs demonstrate the best dynamic performance, reducing heave and pitch by up to 68% and 58%, and mooring tension by 54%. The OWC system achieves the highest power absorption and a 55% capture width ratio, but increases surge and pitch motions by 6% and 27%, respectively, on introducing additional loads on the system. © 2025 Informa UK Limited, trading as Taylor & Francis Group.Item Dynamic analysis of a TLP-type floating wind turbine combined with OWC wave energy converter(Springer Nature, 2025) Sebastian, B.; Joju, A.; Karmakar, D.The present study examines the dynamic effects of integrating oscillating water column wave energy converters on the offset columns of a tension leg floating wind turbine platform in an asymmetric and symmetric configuration. Two configurations are considered, featuring two and four oscillating water columns combined with the tension leg platform supporting a 5 MW wind turbine. The hydrodynamic analysis of the combined wind-wave energy system uses a linear diffraction-radiation tool to compute hydrodynamic coefficients and wave excitation forces in the frequency domain. The coupled dynamic responses of the hybrid platforms are evaluated in the time domain under various irregular sea states, using an aero-hydro-servo-elastic simulation tool. The performance of the hybrid systems is compared with a baseline floating wind turbine platform to quantify changes in dynamic responses. Power absorption of the oscillating water columns is computed using a linear power take-off system. The findings indicate that adding oscillating water columns leads to a slight increase in the heave and pitch motions of the platform. The system with a diagonally placed two-oscillating water column configuration demonstrates higher efficiency, achieving a maximum capture width ratio of 57%. This study provides valuable insights into the feasibility of hybrid offshore renewable energy concepts. It supports the design and implementation of integrated wind-wave systems to deliver clean and sustainable energy. © The Author(s), under exclusive licence to Sociedade Brasileira de Engenharia Naval 2025.