The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Sébastien Gueydon - One of the best experts on this subject based on the ideXlab platform.
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Aerodynamic Damping on a Semisubmersible Floating Foundation for Wind Turbines
Energy Procedia, 2016Co-Authors: Sébastien GueydonAbstract:Abstract The objective of this work is to study the effect of the rotor thrust on the motions of a semisubmersible floating foundation for Horizontal Axis Wind Turbines (HAWT). The main targets are the drift motions and the additional damping caused by the operating rotor, so-called aerodynamic damping. The semisubmersible used in the Offshore Code Comparison Collaboration Continuation (OC4) project, which operated under International Energy Agency (IEA) Wind Task 30, is chosen for this study. Two numerical models are built in aNyPHATAS, a coupled hydrodynamic and aerodynamic tool for simulations of floating wind turbines. The numerical model of the original design of the semisubmersible (OC4), and a numerical model calibrated against model tests (OC5) are compared with measurements. For practical reasons, the physical model at the scale of the basin needs to be adjusted. One key modification is done on the rotor of the wind turbine so that its performance remains equivalent while Froude scaling is applied. This comparison is done for two load cases: operational waves only, operational waves and steady wind simultaneously with a turbine operating at fixed rotation speed (without control). It serves to check the extent to which a design concept and a physical model built at small scale match.
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COMPARISON OF SECOND-ORDER LOADS ON A SEMISUBMERSIBLE FLOATING WIND TURBINE
2015Co-Authors: Sébastien Gueydon, Tiago Duarte, Jason JonkmanAbstract:As offshore wind projects move to deeper waters, floating platforms become the most feasible solution for supporting the turbines. The oil and gas industry has gained experience with floating platforms that can be applied to offshore wind projects. This paper focuses on the analysis of second-order wave loading on semisubmersible platforms. Semisubmersibles, which are being chosen for different floating offshore wind concepts, are particularly prone to slow-drift motions. The slack catenary moorings usually result in large natural periods for surge and sway motions (more than 100 s), which are in the range of the second-order difference-frequency excitation force. Modeling these complex structures requires coupled design codes. Codes have been developed that include turbine aerodynamics, hydrodynamic forces on the platform, restoring forces from the mooring lines, flexibility of the turbine, and the influence of the turbine control system. In this paper two different codes are employed: FAST, which was developed by the National Renewable Energy Laboratory, and aNySIM, which was developed by the Maritime Research Institute Netherlands. The hydrodynamic loads are based on potential-flow theory, up to the second order. Hydrodynamic coefficients for wave excitation, radiation, and hydrostatic forces are obtained with two different panel codes, WAMIT (developed b
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Comparison of Second Order Loads on a Semisubmersible Floating Wind Turbine
Volume 9A: Ocean Renewable Energy, 2014Co-Authors: Sébastien Gueydon, Tiago A. G. Duarte, Jason JonkmanAbstract:As offshore wind projects move to deeper waters, floating platforms become the most feasible solution for supporting the turbines. The oil and gas industry has gained experience with floating platforms that can be applied to offshore wind projects. This paper focuses on the analysis of second-order wave loading on semisubmersible platforms. Semisubmersibles, which are being chosen for different floating offshore wind concepts, are particularly prone to slow-drift motions. The slack catenary moorings usually result in large natural periods for surge and sway motions (more than 100 s), which are in the range of the second-order difference-frequency excitation force.Modeling these complex structures requires coupled design codes. Codes have been developed that include turbine aerodynamics, hydrodynamic forces on the platform, restoring forces from the mooring lines, flexibility of the turbine, and the influence of the turbine control system. In this paper two different codes are employed: FAST, which was developed by the National Renewable Energy Laboratory, and aNySIM, which was developed by the Maritime Research Institute Netherlands. The hydrodynamic loads are based on potential-flow theory, up to the second order. Hydrodynamic coefficients for wave excitation, radiation, and hydrostatic forces are obtained with two different panel codes, WAMIT (developed by the Massachusetts Institute of Technology) and DIFFRAC (developed by MARIN).The semisubmersible platform, developed for the International Energy Agency Wind Task 30 Offshore Code Comparison Collaboration Continuation project is used as a reference platform. Irregular waves are used to compare the behavior of this platform under slow-drift excitation loads. The results from this paper highlight the effects of these loads on semisubmersible-type platforms, which represent a promising solution for the commercial development of the offshore deepwater wind resource.Copyright © 2014 by ASME
Jason Jonkman - One of the best experts on this subject based on the ideXlab platform.
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COMPARISON OF SECOND-ORDER LOADS ON A SEMISUBMERSIBLE FLOATING WIND TURBINE
2015Co-Authors: Sébastien Gueydon, Tiago Duarte, Jason JonkmanAbstract:As offshore wind projects move to deeper waters, floating platforms become the most feasible solution for supporting the turbines. The oil and gas industry has gained experience with floating platforms that can be applied to offshore wind projects. This paper focuses on the analysis of second-order wave loading on semisubmersible platforms. Semisubmersibles, which are being chosen for different floating offshore wind concepts, are particularly prone to slow-drift motions. The slack catenary moorings usually result in large natural periods for surge and sway motions (more than 100 s), which are in the range of the second-order difference-frequency excitation force. Modeling these complex structures requires coupled design codes. Codes have been developed that include turbine aerodynamics, hydrodynamic forces on the platform, restoring forces from the mooring lines, flexibility of the turbine, and the influence of the turbine control system. In this paper two different codes are employed: FAST, which was developed by the National Renewable Energy Laboratory, and aNySIM, which was developed by the Maritime Research Institute Netherlands. The hydrodynamic loads are based on potential-flow theory, up to the second order. Hydrodynamic coefficients for wave excitation, radiation, and hydrostatic forces are obtained with two different panel codes, WAMIT (developed b
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Comparison of Second Order Loads on a Semisubmersible Floating Wind Turbine
Volume 9A: Ocean Renewable Energy, 2014Co-Authors: Sébastien Gueydon, Tiago A. G. Duarte, Jason JonkmanAbstract:As offshore wind projects move to deeper waters, floating platforms become the most feasible solution for supporting the turbines. The oil and gas industry has gained experience with floating platforms that can be applied to offshore wind projects. This paper focuses on the analysis of second-order wave loading on semisubmersible platforms. Semisubmersibles, which are being chosen for different floating offshore wind concepts, are particularly prone to slow-drift motions. The slack catenary moorings usually result in large natural periods for surge and sway motions (more than 100 s), which are in the range of the second-order difference-frequency excitation force.Modeling these complex structures requires coupled design codes. Codes have been developed that include turbine aerodynamics, hydrodynamic forces on the platform, restoring forces from the mooring lines, flexibility of the turbine, and the influence of the turbine control system. In this paper two different codes are employed: FAST, which was developed by the National Renewable Energy Laboratory, and aNySIM, which was developed by the Maritime Research Institute Netherlands. The hydrodynamic loads are based on potential-flow theory, up to the second order. Hydrodynamic coefficients for wave excitation, radiation, and hydrostatic forces are obtained with two different panel codes, WAMIT (developed by the Massachusetts Institute of Technology) and DIFFRAC (developed by MARIN).The semisubmersible platform, developed for the International Energy Agency Wind Task 30 Offshore Code Comparison Collaboration Continuation project is used as a reference platform. Irregular waves are used to compare the behavior of this platform under slow-drift excitation loads. The results from this paper highlight the effects of these loads on semisubmersible-type platforms, which represent a promising solution for the commercial development of the offshore deepwater wind resource.Copyright © 2014 by ASME
Constantine Michailides - One of the best experts on this subject based on the ideXlab platform.
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Second-order hydrodynamic effects on the response of three semisubmersible floating offshore wind turbines
Ocean Engineering, 2020Co-Authors: Lixian Zhang, Wei Shi, Madjid Karimirad, Constantine Michailides, Zhiyu JiangAbstract:Abstract Floating structures have become the most feasible solution for supporting wind turbines when offshore wind project move to deeper water. In this paper, a hydrodynamic analysis of three different semisubmersible floating offshore wind turbines is carried out including second-order hydrodynamic effects. The three examined platforms are V-shaped semisubmersible, Braceless semisubmersible and OC4-DeepCwind semisubmersible and are used to support the NREL 5 MW reference wind turbine. The main objective of the present study is to investigate and compare the hydrodynamic response of the three different semisubmersible floaters in two water depths (100 m, and 200 m) under different load conditions. The effects of second-order wave loads on the platform motions and mooring tension are discussed and compared by using different methods including Newman's approximation and the full QTF (Quadratic transfer function) method. The drag effect on the structure motion response is also discussed in this paper. The comparison presented is based on statistical values and response spectra of floating platform motions as well as mooring tensions. The results show that the dynamic response of semisubmersible FOWTs (floating offshore wind turbines) is overestimated when ignoring the Morison drag effect on the columns of the semisubmersible FOWT. The second-order difference wave loads can excite the resonance of motion especially for the platform-pitch motion, which could cause structural failures. The full QTF method should be used to calculate the second-order wave force to better simulate the realistic dynamic response of semisubmersible FOWTs.
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V-shaped semisubmersible offshore wind turbine: An alternative concept for offshore wind technology
Renewable Energy, 2015Co-Authors: Madjid Karimirad, Constantine MichailidesAbstract:The design aspects of a 5-MW V-shaped semisubmersible floating wind turbine considering the floater main dimensions and configurations are presented in this paper. Initially, the effect of different geometry parameters that correspond to different design cases have been investigated on the hydrostatic stability of the semisubmersible support platform through the comparison of righting arm and righting moments. Afterwards, the dynamic behavior and performance of the V-shaped semisubmersible wind turbine are presented for one of the examined design cases. Aero-hydro-servo-elastic numerical modeling has been applied for achieving coupled integrated time-domain analysis in order to investigate the dynamics of the V-shaped semisubmersible offshore wind turbine. The water depth is selected to be 100 m in order to study the feasibility of such concept in moderate water depth. The wave-induced as well as wave–wind-induced motions, tension of mooring lines and functionality of wind turbine are presented and discussed for selected environmental conditions. In general, the results show that the presented in the present paper V-shaped semisubmersible offshore wind turbine is a promising concept which can enhance the offshore wind industry.
M. Arockiasamy - One of the best experts on this subject based on the ideXlab platform.
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STRUCTURAL INTEGRITY OF Semisubmersibles AND GRAVITY PLATFORMS TO BERGY-BIT/ICEBERG IMPACT
Offshore Technology Conference, 2013Co-Authors: A. S. J. Swamidas, H. El-tahan, M. ArockiasamyAbstract:The results of a series of experimental and numerical studies on the problem of bergy-bit/iceberg collision with semisubmersible/gravity platforms are presented. The numerical study indicates that a 500t bergy-bit travelling at speeds in excess of 2m/s would permanently deform, and possibly puncture, the unstrengthened columns of a semisubmersible, but that if the column is ice-strengthened very little deformation would result from a collision by a 2000t bergy-bit at this speed. Impact resistance tests on fibre-reinforced and plain reinforced concrete shell panels indicate that the fibre-reinforced panels are 1.5 times stronger than ordinary reinforced concrete panels.
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Semisubmersible response to transient ice forces
Ocean Engineering, 2003Co-Authors: M. Arockiasamy, H. El-tahan, A. S. J. Swamidas, W.e. Russell, D.v. ReddyAbstract:The paper presents an analytical and experimental study on the transient response of Semisubmersibles to bergybit impact and the strength of bergybit ice to high strain-rate loadings. Two approaches have been proposed for the solution of the semisubmersible-bergybit interaction problem, one using the energy approach and the other using the conventional structural dynamics approach with initial velocity conditions. In addition the local behaviour of the impacted regions have been analysed for deformation and failure. Numerical results have been given for local behaviour of an impacted column and global behaviour of semisubmersible-bergybit system. Experimental study has been reported on the impact strength of iceberg ice at strain rates of 10−3, 10−2 and 10−1; the indentation impact strength of ice is found to be 3–4 times the unaixial compressive strength, at the same strain rate.
Madjid Karimirad - One of the best experts on this subject based on the ideXlab platform.
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Second-order hydrodynamic effects on the response of three semisubmersible floating offshore wind turbines
Ocean Engineering, 2020Co-Authors: Lixian Zhang, Wei Shi, Madjid Karimirad, Constantine Michailides, Zhiyu JiangAbstract:Abstract Floating structures have become the most feasible solution for supporting wind turbines when offshore wind project move to deeper water. In this paper, a hydrodynamic analysis of three different semisubmersible floating offshore wind turbines is carried out including second-order hydrodynamic effects. The three examined platforms are V-shaped semisubmersible, Braceless semisubmersible and OC4-DeepCwind semisubmersible and are used to support the NREL 5 MW reference wind turbine. The main objective of the present study is to investigate and compare the hydrodynamic response of the three different semisubmersible floaters in two water depths (100 m, and 200 m) under different load conditions. The effects of second-order wave loads on the platform motions and mooring tension are discussed and compared by using different methods including Newman's approximation and the full QTF (Quadratic transfer function) method. The drag effect on the structure motion response is also discussed in this paper. The comparison presented is based on statistical values and response spectra of floating platform motions as well as mooring tensions. The results show that the dynamic response of semisubmersible FOWTs (floating offshore wind turbines) is overestimated when ignoring the Morison drag effect on the columns of the semisubmersible FOWT. The second-order difference wave loads can excite the resonance of motion especially for the platform-pitch motion, which could cause structural failures. The full QTF method should be used to calculate the second-order wave force to better simulate the realistic dynamic response of semisubmersible FOWTs.
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V-shaped semisubmersible offshore wind turbine: An alternative concept for offshore wind technology
Renewable Energy, 2015Co-Authors: Madjid Karimirad, Constantine MichailidesAbstract:The design aspects of a 5-MW V-shaped semisubmersible floating wind turbine considering the floater main dimensions and configurations are presented in this paper. Initially, the effect of different geometry parameters that correspond to different design cases have been investigated on the hydrostatic stability of the semisubmersible support platform through the comparison of righting arm and righting moments. Afterwards, the dynamic behavior and performance of the V-shaped semisubmersible wind turbine are presented for one of the examined design cases. Aero-hydro-servo-elastic numerical modeling has been applied for achieving coupled integrated time-domain analysis in order to investigate the dynamics of the V-shaped semisubmersible offshore wind turbine. The water depth is selected to be 100 m in order to study the feasibility of such concept in moderate water depth. The wave-induced as well as wave–wind-induced motions, tension of mooring lines and functionality of wind turbine are presented and discussed for selected environmental conditions. In general, the results show that the presented in the present paper V-shaped semisubmersible offshore wind turbine is a promising concept which can enhance the offshore wind industry.
