Browsing by Author "Rony, J.S."

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Coupled Dynamic Analysis of Hybrid Offshore Wind Turbine and Wave Energy Converter
(American Society of Mechanical Engineers (ASME), 2022) Rony, J.S.; Karmakar, D.
The combined offshore wind and wave energy on an integrated platform is an economical solution for the offshore energy industry as they share the infrastructure and ocean space. The study presents the dynamic analysis of the Submerged Tension-Leg Platform (STLP) combined with a heaving-type point absorber wave energy converter (WEC). The feasibility study of the hybrid concept is performed using the aero-servo-hydro-elastic simulation tool FAST. The study analyzes the responses of the combined system to understand the influence of the WECs on the STLP platform for various operating conditions of the wind turbine under regular and irregular waves. Positive synergy is observed between the platform and the WECs, and the study also focuses on the forces and moments developed at the interface of the tower and platform to understand the effect of wind energy on the turbine tower and the importance of motion amplitudes on the performance of the combined platform system. The mean and standard deviation for the translation and rotational motions of combined wind and wave energy converters are determined for different sea states under both regular and irregular waves to analyze the change in responses of the structure. The study observed a reduction in motion amplitudes of the hybrid floating system with the addition of the wave energy converters around the STLP floater to improve the energy efficiency of the hybrid system. The study helps in understanding the best possible arrangement of point absorber-type wave energy converters at the conceptual stage of the design process. © © 2021 by ASME
Coupled dynamic analysis of hybrid STLP-WEC offshore floating wind turbine with different mooring configurations
(Springer Science and Business Media Deutschland GmbH, 2023) Rony, J.S.; Karmakar, D.
The novel concept of six cone-cylinder-shaped point absorbers around the submerged tension leg platform (STLP) in a circular pattern is studied considering the STLP fixed in position using tensioned mooring cables. The hybrid floating platform consisting of offshore wind turbine platform with a wave energy converter (WEC) reduces the overall logistic cost and eases the transportation process. The stability and safety of the hybrid floating concept depend significantly on the integrity of the tensioned tendons. The present study proposes four different mooring configurations (four, five, eight and nine) to stabilize the hybrid STLP-WEC floater. The numerical simulation in the time domain is performed using the aero-servo-hydro-elastic simulation. The time histories and the motion response spectrums of the surge, sway, heave, roll, pitch and yaw motion of the hybrid system for each mooring configuration are analyzed to study the behaviour of the hybrid system under irregular wave conditions. The time history and spectrum of the generator power are analysed to observe the effect of second-order wave load and turbulent wind loads on the power production of the hybrid floater under each mooring configuration. Further, the study is performed to determine the forces and moments developed at the base of the floating wind turbine to analyze the impact of wind load on the responses of the hybrid floater. The study also analyses the tension developed on each tendon for different mooring configurations and reports the importance of mooring and the influence of the mooring system on the dynamic responses of the combined floater. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
Coupled dynamic analysis of spar-type floating wind turbine under different wind and wave loading
(Springer Science and Business Media Deutschland GmbH, 2021) Rony, J.S.; Karmakar, D.; Guedes Soares, C.G.
In the present study, the coupled dynamic modelling of three different configurations of spar platform is performed using time-domain aero-servo-hydro-elastic simulation. The spar platforms are coupled with 5 MW NREL floating wind turbine and mooring sub-models. The coupled aero-servo-hydro-elastic simulation is performed using the simulation tool FAST with WAMIT as the sub module to obtain frequency domain hydrodynamic characteristics. The major emphasis is given to analyse the Response Amplitude Operators (RAOs) to understand the stability of the structures. The responses are calculated for surge, sway, heave, roll, pitch and yaw motions. The study determines the performance of the structure under the wind load developed for the turbine support structure on analysing the tower base forces and moments. The analysis for three different configurations of spar platform is performed for various environmental conditions of North Sea. The studies observed that the responses of the platforms tend to increase with increase in wind speed and wave height. Further, it is observed that surge and pitch motion is dominant for all the three configurations of spar platform. The present study provides an insight into the power performance, structural integrity and dynamic motions of the floating wind turbine under various operational and survival conditions which help the designers to develop better design standards. © 2021, Sociedade Brasileira de Engenharia Naval.
Dynamic analysis of frustum TLP-type wind turbine multi-purpose floating platform
(Taylor and Francis Ltd., 2024) Rony, J.S.; Karmakar, D.
The coupled dynamic analysis of a hexagon-shaped Frustum Tension-leg platform (FTLP) combined with wave energy converters (WECs) supporting a 5-MW wind turbine is performed to analyse the dynamic responses of the hybrid system. The responses of the FTLP are investigated using the time-domain numerical simulation for the operational sea-states of the wind turbine. The FTLP is integrated with an array of point absorber-type WECs in a circular pattern to analyse the influence of the WECs on the dynamic responses of the floating platform. The aero-servo-hydro-elastic simulation tool FAST and hydrodynamic simulation tool WAMIT is used to study the rigid body motions of the system. The study observes higher rigid body motions in the surge, sway and yaw directions for the hybrid system. Further, the investigation is performed for the forces and moments developed at the base of the wind turbine and the tension developed on mooring cables to understand the integrity and stability of the hybrid platform. © 2023 Informa UK Limited, trading as Taylor & Francis Group.
Dynamic analysis of submerged tension leg platform combined with wave energy converters for different mooring configuration
(American Institute of Physics Inc., 2023) Rony, J.S.; Karmakar, D.
In the present study floating wind turbine combined with a wave energy converter is analysed deriving both wind and wave energy, and thus ensuring continuous supply of energy. The study combines a submerged tension leg platform (STLP) with heaving type point absorber wave energy converter (WEC). Submerged tension leg platform is stable in both transportation phase and operational phase. The point absorber WEC has a floater system having diameter smaller than the incident wave length. The floater tends to oscillate in one or more degrees of freedom (DOF) and absorbs energy by damping the floater motion and converting it into electrical energy. The study combines STLP floater with six wave energy converters in circular pattern. The time domain simulation is performed for the combined platform configuration using fully coupled aero-hydro-servo-elastic simulation tool FAST developed by NREL for different mooring line configuration. The analysis is performed to study the responses (surge, sway, heave, roll, pitch, yaw) for the combined configuration for wind and wave load conditions corresponding to North Atlantic Ocean. The tower base bending moment, shear force and the tension developed on the mooring lines of the combined platform is analysed along with the responses of the floating combined energy platform. The study performed is expected to provide an insight into the dynamic motions and structural integrity of the floating wind and wave concept under different survival conditions helping the designers to develop better design standards. Â© 2023 Author(s).
Dynamic analysis of submerged TLP wind turbine combined with heaving wave energy converter
(CRC Press/Balkema, 2021) Rony, J.S.; Karmakar, D.; Guedes Soares, C.G.
A submerged tension-leg-platform for offshore wind turbine combined with a heaving type point absorber wave energy converter is analysed considering different configurations of array of wave energy converters. A time domain simulation is performed for the combined platform using fully coupled aero-hydro-servo-elastic simulation. The analysis is performed to study the effect of different combinations of wave energy converters on the responses of the proposed system. The responses considered for the study include the six degrees of motion along with tower base bending moment and shear force of the combined wind and wave energy platform. The study will provide an insight into the dynamic motions of the floating wind and wave concept under operating condition, which will help the designers to develop better design standards. Â© 2021 the Author(s).
Dynamic response analysis of a combined wave and wind energy platform under different mooring configuration
(CRC Press, 2022) Rony, J.S.; Karmakar, D.; Guedes Soares, C.G.
In the present study, a novel concept of combining a submerged tension leg platform (STLP) with six heaving type point absorbers WEC in circular pattern is presented for different mooring configur-ations. The tensioned tendons are used to fix the floating combined wave and wind energy system in position. The safety, stability and power production of the combined floating platform depends significantly on the integrity of the tendons. The combined wind and wave platform supported by four, five, eight and nine tendons are analysed for the operating conditions of the 5MW wind turbine under regular waves. Time domain numerical simulation tool FAST developed by NREL is used to perform the aero-servo-hydro-elastic simulation. The spectra of surge, sway, roll, pitch and yaw motion of the combined system under each mooring configuration is presented to analyze the behavior of the combined wave and wind energy system. Statistical results on the tension developed on each tendon for different mooring configurations is also presented to study the import-ance of mooring and the influence of mooring system on the dynamic responses of the combined floater. The study performed will be helpful in the design and analysis of possible configurations of mooring lines support-ing the floating platform and improving the structural integrity of the combined floating concept. © 2022 the Author(s).
Extreme response analysis for TLP-type floating wind turbine using Environmental Contour Method
(CRC Press, 2022) Sreebhadra, M.N.; Rony, J.S.; Karmakar, D.; Guedes Soares, C.G.
The reliability of structures against extreme loading conditions is a significant factor to be accounted for the design of marine structures. In Environmental Contour Method, using inverse reliability technique the most significant contributing environmental factors associated with the structure at the particular site can approximately give the long-term extreme response. In the present study, the extreme responses on five different configurations of TLP-type floating offshore wind turbine are analysed using the environmental contour method. The various responses including the maximum and minimum tower base bending moment loads at the blade root, tower base shear force is studied. The simulations are performed for the different wind speed and wave and a comparative study is made for the different TLP-type platforms. The estimation of extreme responses is obtained using the Environmental Contour Method and the present study will be helpful for the long-term load estimation of offshore structures. © 2022 the Author(s).
Hydrodynamic response analysis of a hybrid TLP and heaving-buoy wave energy converter with PTO damping
(Elsevier Ltd, 2024) Rony, J.S.; Karmakar, D.
In the present study, the numerical investigation is performed to analyse the hydrodynamic performance of circular and concentric arrangements of cone-cylinder-type heaving point absorber wave energy converter (WEC) around a Frustum Tension-Leg Platform (FTLP) based on potential flow theory. The responses of the single FTLP and the FTLP-WEC hybrid system are analysed for the rated wind speed of a 5 MW wind turbine to observe the influence of the WECs on wind power absorption of wind turbines supported on FTLP. The presence of the FTLP floating wind turbine platform and other WECs affects the hydrodynamic coefficients of the WEC. The influence of the hybrid system on the hydrodynamic coefficients is analysed on determining the ratio of the hydrodynamic coefficients for a single WEC system to those for a hybrid system. Further, the study analyses the instantaneous wave power absorption for the WECs arranged around the FTLP in a circular and concentric pattern. The hydraulic power take-off for the hybrid system with two different control strategies is then discussed to improve the wave power absorption of the WECs. The study observed higher wave power absorption of the WECs with the influence of the PTO system. The mean interaction factor and the capture width ratio of the hybrid system are further studied to understand the influence of array arrangement for the WECs. The hybrid system is noted to have favourable dynamic responses for different environmental factors and contributes positively in increasing power output. © 2024 Elsevier Ltd
Long-term response analysis of hybrid STLP-WEC offshore floating wind turbine
(Taylor and Francis Ltd., 2025) Rony, J.S.; Karmakar, D.
In the present study, time-domain response analysis of different configurations of a hybrid Submerged Tension Leg Platform (STLP) combined with a Point Absorber-type Wave Energy Converter (WEC) (STLPWEC) is performed using the aero-servo-hydro-elastic simulation. The study employs long-term analysis technique to predict the most probable values of motion amplitudes, and the forces and moments developed at the tower base for the hybrid STLP-WEC system under operational wind speed conditions of the 5 MW wind turbine. The long-term distribution is performed using short-term responses based on Rayleigh distribution and North Atlantic wave data. The performance of the offshore STLP-WEC system depends on both the transfer functions (translational and rotational motions) and the wave spectrum model. A comparative study of the long-term responses using JONSWAP spectrum model for different configurations of the hybrid STLP-WEC systems is performed, providing valuable insights for designing floating hybrid systems. © 2025 Informa UK Limited, trading as Taylor & Francis Group.
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.
Performance of a hybrid TLP floating wind turbine combined with arrays of heaving point absorbers
(Elsevier Ltd, 2023) Rony, J.S.; Karmakar, D.
In the present study, the hydrodynamic performance of circular and concentric arrangements of cone-cylinder-type heaving point absorbers around a Submerged Tension-Leg Platform (STLP) is analysed using the numerical model in the frequency domain based on the potential flow theory. The presence of the Wave Energy Converters (WECs) around the STLP floating wind turbine platform affects the hydrodynamic performance of the hybrid floating platform. So to illustrate the effects of WECs on the platform, the ratio of hydrodynamic coefficients for a single WEC system to that for a hybrid system is analysed. An array of heaving point absorbers is placed in circular and concentric patterns to understand the performance of heaving point absorbers in the absorption of wave energy. The cone-cylinder type heaving point absorber is selected for the present study as they yield more power as compared to other shaped point absorbers. The study compares the wave power absorption of each point absorber around the platform for irregular wave conditions of the North Sea. The effect of incoming waves is illustrated by analysing four different wave heading angles. To quantify the performance of the WECs in an array, the q-factor and coefficient of variation are studied for each array at different sea states. The study suggested the best possible arrangement pattern for wave power absorption and power uniformity among the floaters in the array. The study performed will be helpful in the design and analysis of the possible arrangement of point absorbers around the floating wind turbine platform for wave power absorption. © 2023 Elsevier Ltd
Reliability based design loads of hybrid submerged tension leg-type offshore wind turbine platform
(Springer Science and Business Media Deutschland GmbH, 2025) Rony, J.S.; Karmakar, D.
The environmental contour (EC) method is one of the popular modelling approaches to predict the long-term responses of the Floating Offshore Wind Turbine (FOWT) platforms. The method is recommended in the design guidelines and standards as, it emerged as a practical method to estimate the extreme dynamic responses for relatively minimal number of environmental conditions. The EC method has the advantage of separating the probabilistic description of the environment from the structural design. In the present study the 1-D and 2-D EC models are estimated based on the Inverse First Order Reliability Method (IFORM). The models estimated were used to predict the extreme long-term responses of the single Submerged Tension Leg Platform (STLP) and the STLP combined with heaving cone-cylinder wave energy converters (STLP-WEC). The aero-servo-hydro-elastic simulation tool FAST is used to simulate the extreme responses for the five particular return periods (1-Year, 10-Year, 20-Year, 50-Year and 100-Year) considering the HornsRev site. The wind load conditions for the FAST platform were simulated using the tool TURBSIM. The study further analysed the long-term extreme moments developed at the base of the turbine tower to analyse the influence of the wind and wave load on the wind power absorption. The maximum value of the mooring line tension developed on the mooring cables of the platform for different return period conditions are also studied to understand the reliability of the floating system. The study observed to be useful for predicting the long-term design loads of STLP wind turbine. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.