Browsing by Author "Guedes Soares, C.G."

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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 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 performance of semi-submersible FOWT combined with point-absorber WECs
(CRC Press/Balkema, 2021) Hallak, T.S.; Karmakar, D.; Guedes Soares, C.G.
The numerical investigation is carried out for a hybrid platform for wind and wave energy conversion in the offshore. The analyses are for the DeepCWind semi-submersible as main hull of the Floating Offshore Wind Turbine having 20.0 meters draft, whereas the Wave Energy Converters are conical point-absorbers of diameter within 5.0 â€“ 10.0 meters. The investigation is focused towards the linear hydrodynamic interaction of the wind platform and wave energy devices; the turbine is considered to be non-operative. The wave diffraction/ radiation approach is considered for the evaluation of single-and multi-body hydrodynamic coefficients. The numerical investigation is performed to determine devicesâ€™ Response Amplitude Operators and response spectra. Performance parameters are also evaluated, such as wave convertersâ€™ capture width, absorbed power and arrayâ€™s q-factor. The study presents a preliminary investigation on the hydrodynamic performance of the hybrid platform, it currently oversimplifies the mechanical coupling created by the Power Take-Offs and connection constraints. Â© 2021 the Author(s).
Hydroelastic analysis of articulated floating elastic plate based on Timoshenko–Mindlin plate theory
(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2018) Praveen, P.; Karmakar, D.; Guedes Soares, C.G.
The wave interaction with articulated floating elastic plate is investigated considering the Timoshenko–Mindlin thick plate theory for both finite and shallow water depths. The elastic plates are modelled as finite flexible floating structure interconnected with vertical linear/rotational spring stiffness. The eigenfunction expansion method along with the orthogonal mode-coupling relation is used to analyse the hydrodynamic behaviour of the interconnected structure. The study is performed for different articulated edge conditions for varying plate thickness and water depths to understand the behaviour of articulation under the action of an ocean wave. The hydroelastic response of the interconnected floating elastic plate with different connector stiffness is observed to compare well with the result available in the literature. The present study provides an insight into the effect of articulated joints with varying spring stiffness for the suitable design of the structure. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.
Influence of damping on an oscillating water column wec integrated with a breakwater
(CRC Press/Balkema, 2019) Rajan, S.N.; Karmakar, D.; Guedes Soares, C.G.
In the present study, the oscillating water column under consideration is integrated with caisson type breakwater. The air column under pressure due to the damping from the PTO device drives the turbine placed at the orifice of OWC. The relationship between the hydrodynamic efficiency of the OWC and the PTO damping is analyzed which would give more precision about efficient wave energy extraction using an OWC. The PTO damping on the chamber is characterized using a linear pressure drop law with the permeability coefficient derived from Darcyâ€™s equation for flow through porous media. An open Computational Fluid Dynamics tool, REFF3D, is used for the simulations to analyze the reaction of the OWC under different different damping conditions due to the PTO device. Flat bottom and slope bottom configurations are studied and the results are obtained for zero damping, low damping, moderate damping and high damping. The hydrodynamic efficiency for the flat and slope bottom configurations with breakwater are compared to analyze the performance of OWC integrated with breakwater due to the change in the bottom configuration inside the OWC chamber. Â© 2019 Taylor & Francis Group, London.
Influence of Support Conditions on the Hydroelastic Behaviour of Floating Thick Elastic Plate
(Harbin Engineering University, 2019) Praveen, K.M.; Karmakar, D.; Guedes Soares, C.G.
The hydroelastic response of very large floating structures (VLFS) under the action of ocean waves is analysed considering the small amplitude wave theory. The very large floating structure is modelled as a floating thick elastic plate based on Timoshenko-Mindlin plate theory, and the analysis for the hydroelastic response is performed considering different edge boundary conditions. The numerical study is performed to analyse the wave reflection and transmission characteristics of the floating plate under the influence of different support conditions using eigenfunction expansion method along with the orthogonal mode-coupling relation in the case of finite water depth. Further, the analysis is extended for shallow water depth, and the continuity of energy and mass flux is applied along the edges of the plate to obtain the solution for the problem. The hydroelastic behaviour in terms of reflection and transmission coefficients, plate deflection, strain, bending moment and shear force of the floating thick elastic plate with support conditions is analysed and compared for finite and shallow water depth. The study reveals an interesting aspect in the analysis of thick floating elastic plate with support condition due to the presence of the rotary inertia and transverse shear deformation. The present study will be helpful for the design and analysis of the VLFS in the case of finite and shallow water depth. © 2019, Harbin Engineering University and Springer-Verlag GmbH Germany, part of Springer Nature.
Numerical investigation of semi-submersible floating wind turbine combined with flap-type WECs
(Springer, 2019) Kumawat, A.K.; Karmakar, D.; Guedes Soares, C.G.
Offshore renewable energy has great potential to meet the increasing energy demands. Ammon different energy source, the offshore wave and wind energy are considered the best possible option as renewable source. To increase renewable energy yield per unit square kilometre of ocean space, there is an increasing interest in investigating the technological and the economic feasibility of combining offshore wind turbines with wave energy converters. In the past two decades, combined concepts of utilizing different floating support platforms and wave energy converters have been studied. In the present study, the hydrodynamic coefficients and response amplitude operators (RAOs) of semi-submersible floater combined with flap-type wave energy converter is analysed. The semi-submersible floater with flap-type wave energy converter is a combined concept of wave and wind energy converters which consists of three elliptical cylinder flap-type wave energy converters (WECs) and a 5 MW floating wind turbine installed on semi-submersible platform. The hydrodynamic coefficients are calculated in frequency domain and the power take off (PTO) system is modelled as a linear damper and spring. A parametric study is made to compute hydrodynamic coefficients of flap and three column semi-submersible platform combined wave and wind energy system. Further, RAO analysis is performed for three column semi-submersible platform relative to combined wave and wind energy platform with incident wave heading angles. © Springer Nature Singapore Pte Ltd. 2019.
Wave energy conversion by multiple bottom-hinged surging WEC
(Springer, 2019) Kumawat, A.K.; Karmakar, D.; Guedes Soares, C.G.
The power capture and performance of arbitrary array of submerged bottom-hinged deflectors of finite width is analysed for two different configurations. The bottom-hinged deflectors are modelled as non-zero thickness and rotated at small angle in the vertical plane about an axis located in the seabed orthogonal to the direction of the wave propagation. The numerical study is performed on the hydrodynamic performance of the flapping deflector type oscillating wave surge converter (OWSC). Three-dimensional boundary element method is used to calculate hydrodynamic coefficients in frequency domain. A parametric study was made by comparing two geometrically different deflectors, i.e., rectangular and wedge cross-section for power capture assessment. Further, the analysis is performed for arbitrary array configurations of OWSC with oblique incident wave heading angles and the power take off (PTO) system is modelled as a linear damper and spring. The study for multiple arrays of the flap-type wave energy converters is essential for economical design of project in order to exploit more renewable energy from the ocean waves. © Springer Nature Singapore Pte Ltd. 2019.