scholarly journals A Comprehensive Study on the Serbuoys Offshore Wind Tension Leg Platform Coupling Dynamic Response under Typical Operational Conditions

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2067
Author(s):  
Zhe Ma ◽  
Nianxin Ren ◽  
Yin Wang ◽  
Shaoxiong Wang ◽  
Wei Shi ◽  
...  
Keyword(s):  
Modal Analysis ◽  
Coupling Effect ◽  
Suppressive Effect ◽  
Wave Period ◽  
Offshore Wind ◽  
Tension Leg Platform ◽  
Mooring Lines ◽  
Motion Response ◽  
Operational Conditions ◽  
Motion Characteristics

A new type of offshore wind tension leg platform (TLP) connected with a series of buoys (Serbuoys-TLP) is proposed. With the consideration of coupling effect, derivations on the stiffness of the Serbuoys-TLP mooring lines are given. The complicated coupling motion characteristics of the TLP with buoys system are investigated by means of experiments and numerical analysis. The suppressive efficiency on the surge under some condition is nearly 68%, when the wave period is the common wave period of the East China Sea (6 s). Namely, the suppressive effect of series buoys on surge motion response of TLP is analyzed. Through several aspects of suppressive effect on the surge including wave properties, submerge volume and position of buoys are investigated. The modal analysis method is also adopted to interpret the coupled motion response. In the end, the responses of TLP and Serbuoys-TLP are simulated under actual sea conditions with the consideration of wind, wave and current. Based on the parametric study using the modal analysis combined with hydrodynamic analysis, the conclusion can be drawn that the surge of TLP can be effectively suppressed by the addition of a series of buoys in the Serbuoys-TLP.

scholarly journals Study of Floating Wind Turbine with Modified Tension Leg Platform Placed in Regular Waves

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 703 ◽  
Author(s):  
Juhun Song ◽  
Hee-Chang Lim
Keyword(s):  
Wind Turbine ◽  
Real Data ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Wave Loads ◽  
Tension Leg Platform ◽  
Mooring Lines ◽  
Floating Wind Turbine ◽  
Wave Conditions

In this study, the typical ocean environment was simulated with the aim to investigate the dynamic response under various environmental conditions of a Tension Leg Platform (TLP) type floating offshore wind turbine system. By applying Froude scaling, a scale model with a scale of 1:200 was designed and model experiments were carried out in a lab-scale wave flume that generated regular periodic waves by means of a piston-type wave generator while a wave absorber dissipated wave energy on the other side of the channel. The model was designed and manufactured based on the standard prototype of the National Renewable Energy Laboratory (NREL) 5 MW offshore wind turbine. In the first half of the study, the motion and structural responses for operational wave conditions of the North Sea near Scotland were considered to investigate the performance of a traditional TLP floating wind turbine compared with that of a newly designed TLP with added mooring lines. The new mooring lines were attached with the objective of increasing the horizontal stiffness of the system and thereby reducing the dominant motion of the TLP platform (i.e., the surge motion). The results of surge translational motions were obtained both in the frequency domain, using the response amplitude operator (RAO), and in the time domain, using the omega arithmetic method for the relative velocity. The results obtained show that our suggested concept improves the stability of the platform and reduces the overall motion of the system in all degrees-of-freedom. Moreover, the modified design was verified to enable operation in extreme wave conditions based on real data for a 100-year return period of the Northern Sea of California. The loads applied by the waves on the structure were also measured experimentally using modified Morison equation—the formula most frequently used to estimate wave-induced forces on offshore floating structures. The corresponding results obtained show that the wave loads applied on the new design TLP had less amplitude than the initial model and confirmed the significant contribution of the mooring lines in improving the performance of the system.

Motion Behaviour of a New Offshore LNG Transfer System at Harsh Operational Conditions

2009 ◽  
Author(s):  
Gu¨nther F. Clauss ◽  
Florian Sprenger ◽  
Daniel Testa ◽  
Sven Hoog ◽  
Roland Huhn
Keyword(s):  
Natural Gas ◽  
Transfer System ◽  
Mooring Lines ◽  
Operational Conditions ◽  
The North ◽  
Processing Plants ◽  
Limiting Parameters ◽  
Motion Characteristics ◽  
High Level ◽  
Operational Range

Today, the demand of natural gas from offshore fields is on a high level and still increasing. Floating turret moored terminals receive gas directly from the field via risers and liquefaction is achieved by on-board processing plants. The LNG (liquefied natural gas) is transferred to periodically operating shuttle carriers for onshore supply. This paper presents an innovative offshore LNG transfer system, based on newly developed flexible cryogenic pipes of 16″ inner diameter, which allow fast loading/offloading procedures in tandem configuration (see Fig. 1), even in harsh environmental conditions. The motion characteristics of the proposed concept are investigated in detail by the potential theory programmes WAMIT and ANSYS AQWA, respectively, with the focus on the dynamic behaviour of the multi-body system in waves. Each vessel is generating its own radiation and diffraction wave field affecting the motions of the adjacent vessels and vice versa. Results from calculations in the frequency and time domain are compared and show good agreement. Tolerable relative motions between terminal and carrier are limited by maximum torsion and bending of the flexible transfer pipe. Based on given limiting parameters, the operational range of the system and the annual expected downtime is exemplarily calculated for a location in the north sea. Finally, second-order forces — induced by drift motions — on the mooring lines between carrier and terminal are presented as time series for a three-hour sea state.

Research on Time-Domain Dynamic Response of Tension Leg Platform in Regular Wave

2014 ◽  
Vol 670-671 ◽  
pp. 801-804
Author(s):  
Wei Min Liu
Keyword(s):  
Dynamic Response ◽  
Wave Height ◽  
Incident Wave ◽  
Time Domain ◽  
Wave Period ◽  
Regular Wave ◽  
Tension Leg Platform ◽  
Response Characteristics ◽  
Motion Characteristics ◽  
The Time Domain

Move performance in six-degree-of-freedom is one of the important indexes of hydro-dynamic property of tension leg platform (TLP). This paper discusses the time domain dynamic response characteristics of a tension leg platform in the regular wave. The paper focuses on the effects of the incident wave angles (15 °, 22.5 ° and 45 °), the wave height (6m, 8m and 10m) and the wave period (10s, 12s and 14s) on the movement of tension leg platform, the top tension of the tension leg. The results show that: because of the different sensitivity of the tension leg platform to the incident wave angle, the wave height and the wave period, the motion characteristics is different.

Performance Research on Tension Leg Platform of Floating Offshore Wind Turbine

2013 ◽  
Vol 724-725 ◽  
pp. 645-648
Author(s):  
Yue Wen Gao ◽  
Chun Li ◽  
Xin Cheng
Keyword(s):  
Wind Turbine ◽  
Time Domain ◽  
Reference Value ◽  
Wave Force ◽  
Offshore Wind ◽  
Maximum Response ◽  
Offshore Wind Turbine ◽  
Tension Leg Platform ◽  
Motion Response ◽  
Motion Responses

Platform structure is the basic guarantee for safety operation of offshore wind turbine. Based on the boundary element method and combined with multi-body dynamics, analyzing motion response and wave force mechanism to the platform structure, and obtained the dynamic response and the wave force change of the platform structures in time domain, last analyzes the motion response and wave force change of tension leg platform in surge, sway and heave also roll, pitch and yaw direction. The results show that the maximum response of sway and the minimum response of surge have the same direction, it is the same with the maximum response of pitch and the minimum response of roll ; Motion responses of heave and yaw change not as acutely as other four directions ; In time-domain variation range, motion response of surge, heave and pitch change acutely, while motion responses of sway, roll and yaw change slightly. Wave force focus mostly in heave and pitch direction. The results is high reference value on offshore tension leg platform structural design and optimization.

Motion Characteristics of TLP Type Offshore Wind Turbine in Waves and Wind

2010 ◽  
Author(s):  
Yasunori Nihei ◽  
Hiroyuki Fujioka
Keyword(s):  
Wind Turbine ◽  
Reduction Rate ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wind Effect ◽  
Generation System ◽  
Mooring Lines ◽  
Wind Energy Generation ◽  
Motion Characteristics ◽  
Generation Power

In this research, we propose a new offshore wind energy generation system that uses a Tension Leg Platform (TLP) and performed the experimental test of the TLP type wind turbine both in waves and in wind. The authors used a 1/100 scale wind turbine. Not only the motion characteristics, but also the loads of the tension legs and the bending moments of the tower were revealed in this paper. From the research, the following conclusions were mainly obtained. 1) In the case of waves-wind coexisting condition, the wind effect stabilizes the pitch motion compared with in only waves. 2) The wind effect is decreasing the vibration of the mooring lines in waves and wind coexisting field. Especially, the springing (2nd order or 3rd order force) is also decreasing in this field. 3) It can be estimated that the amount of reduction rate of electricity generation power is up to about 6% from the results of the heel angle.

Motion Response Analysis of FPSO’s CALM Buoy Offloading System

2015 ◽  
Author(s):  
Liping Sun ◽  
Xu Zhang ◽  
Youwei Kang ◽  
Shuhong Chai
Keyword(s):  
Oil And Gas ◽  
Numerical Models ◽  
Response Analysis ◽  
Floating Bodies ◽  
Mooring Lines ◽  
Motion Response ◽  
Operation Conditions ◽  
Practical Engineering ◽  
Offshore Oil And Gas ◽  
Motion Characteristics

Catenary anchor legs mooring (CALM) buoy offloading system is widely used in offshore oil and gas exploitation engineering. Proper prediction of the motion response of CALM systems is very important to the fatigue analysis of offloading pipelines and the design of mooring lines. Numerical models of a CALM system in survival and operation conditions will be established in this paper, and motion characteristics of the buoy and its sensibility to environmental factors, as well as performance of slender bodies are derived. More importantly, the shuttle tanker’s stability in plane and the risk of its collision with other floating bodies are focused on in this paper. All of the conclusions will provide recommendation for designing in practical engineering.

scholarly journals Seakeeping Tests of a FOWT in Wind and Waves: An Analysis of Dynamic Coupling Effects and Their Impact on the Predictions of Pitch Motion Response

2021 ◽  
Vol 9 (2) ◽  
pp. 179
Author(s):  
Giovanni Amaral ◽  
Pedro Mello ◽  
Lucas do Carmo ◽  
Izabela Alberto ◽  
Edgard Malta ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Dynamic Coupling ◽  
Coupling Effects ◽  
Mooring Lines ◽  
Scaled Model ◽  
Wave Basin ◽  
Domain Models ◽  
Catenary System

The present work highlights some of the dynamic couplings observed in a series of tests performed in a wave basin with a scaled-model of a Floating Offshore Wind Turbine (FOWT) with semi-submersible substructure. The model was moored by means of a conventional chain catenary system and an actively controlled fan was used for emulating the thrust loads during the tests. A set of wave tests was performed for concomitant effects of not aligned wave and wind. The experimental measurements illustrate the main coupling effects involved and how they affect the FOWT motions in waves, especially when the floater presents a non-negligible tilt angle. In addition, a frequency domain numerical analysis was performed in order to evaluate its ability to capture these effects properly. The influence of different modes of fan response, floater trim angles (changeable with ballast compensation) and variations in the mooring stiffness with the offsets were investigated in the analysis. Results attest that significant changes in the FOWT responses may indeed arise from coupling effects, thus indicating that caution must be taken when simplifying the hydrodynamic frequency-domain models often used as a basis for the simulation of FOWTs in waves and in optimization procedures for the design of the floater and mooring lines.

scholarly journals Effect of Roughness of Mussels on Cylinder Forces from a Realistic Shape Modelling

2021 ◽  
Vol 9 (6) ◽  
pp. 598
Author(s):  
Antoine Marty ◽  
Franck Schoefs ◽  
Thomas Soulard ◽  
Christian Berhault ◽  
Jean-Valery Facq ◽  
...  
Keyword(s):  
Marine Species ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Mooring Lines ◽  
Shape Modelling ◽  
Offshore Wind Turbines ◽  
Specific Effects ◽  
Hydrodynamic Loading ◽  
Floating Offshore Wind Turbines ◽  
Realistic Shape

After a few weeks, underwater components of offshore structures are colonized by marine species and after few years this marine growth can be significant. It has been shown that it affects the hydrodynamic loading of cylinder components such as legs and braces for jackets, risers and mooring lines for floating units. Over a decade, the development of Floating Offshore Wind Turbines highlighted specific effects due to the smaller size of their components. The effect of the roughness of hard marine growth on cylinders with smaller diameter increased and the shape should be representative of a real pattern. This paper first describes the two realistic shapes of a mature colonization by mussels and then presents the tests of these roughnesses in a hydrodynamic tank where three conditions are analyzed: current, wave and current with wave. Results are compared to the literature with a similar roughness and other shapes. The results highlight the fact that, for these realistic roughnesses, the behavior of the rough cylinders is mainly governed by the flow and not by their motions.

scholarly journals Impact of Typhoons on Floating Offshore Wind Turbines: A Case Study of Typhoon Mangkhut

2021 ◽  
Vol 9 (5) ◽  
pp. 543
Author(s):  
Jiawen Li ◽  
Jingyu Bian ◽  
Yuxiang Ma ◽  
Yichen Jiang
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Safety Evaluation ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Motion Response ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Coupling Motion

A typhoon is a restrictive factor in the development of floating wind power in China. However, the influences of multistage typhoon wind and waves on offshore wind turbines have not yet been studied. Based on Typhoon Mangkhut, in this study, the characteristics of the motion response and structural loads of an offshore wind turbine are investigated during the travel process. For this purpose, a framework is established and verified for investigating the typhoon-induced effects of offshore wind turbines, including a multistage typhoon wave field and a coupled dynamic model of offshore wind turbines. On this basis, the motion response and structural loads of different stages are calculated and analyzed systematically. The results show that the maximum response does not exactly correspond to the maximum wave or wind stage. Considering only the maximum wave height or wind speed may underestimate the motion response during the traveling process of the typhoon, which has problems in guiding the anti-typhoon design of offshore wind turbines. In addition, the coupling motion between the floating foundation and turbine should be considered in the safety evaluation of the floating offshore wind turbine under typhoon conditions.

Coupled Dynamic Analysis for Multi-Unit Floating Offshore Wind Turbine in Maximum Operational and Survival Conditions

2015 ◽  
Author(s):  
H. K. Jang ◽  
H. C. Kim ◽  
M. H. Kim ◽  
K. H. Kim
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Time Domain ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Random Waves ◽  
Mooring Lines ◽  
Floating Offshore Wind Turbine ◽  
Coupled Dynamic Analysis ◽  
Floating Offshore Wind Turbines

Numerical tools for a single floating offshore wind turbine (FOWT) have been developed by a number of researchers, while the investigation of multi-unit floating offshore wind turbines (MUFOWT) has rarely been performed. Recently, a numerical simulator was developed by TAMU to analyze the coupled dynamics of MUFOWT including multi-rotor-floater-mooring coupled effects. In the present study, the behavior of MUFOWT in time domain is described through the comparison of two load cases in maximum operational and survival conditions. A semi-submersible floater with four 2MW wind turbines, moored by eight mooring lines is selected as an example. The combination of irregular random waves, steady currents and dynamic turbulent winds are applied as environmental loads. As a result, the global motion and kinetic responses of the system are assessed in time domain. Kane’s dynamic theory is employed to formulate the global coupled dynamic equation of the whole system. The coupling terms are carefully considered to address the interactions among multiple turbines. This newly developed tool will be helpful in the future to evaluate the performance of MUFOWT under diverse environmental scenarios. In the present study, the aerodynamic interactions among multiple turbines including wake/array effect are not considered due to the complexity and uncertainty.

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