Dynamic Analysis of a Tension Leg Platform Under Combined Wind and Wave Loads Within the Typhoon Area

2016 ◽  
Author(s):  
Bin Wang ◽  
Yougang Tang ◽  
Wei Li ◽  
Jiawei Zhai
Keyword(s):  
Dynamic Analysis ◽  
Wave Height ◽  
Empirical Formula ◽  
Tangential Velocity ◽  
Maximum Velocity ◽  
Production Operation ◽  
Wave Loads ◽  
Tension Leg Platform ◽  
Coupled Motion ◽  
Restoring Stiffness

The dynamic analysis of a Tension Leg Platform (TLP) is investigated by combining wind and wave loads within the typhoon area. By considering different typhoon parameters, such as the tangential velocity, the radius of maximum velocity, the translational direction and velocity, the model of typhoon is established. The wave height and period are obtained by the empirical formula related to the parameters of typhoon. The nonlinear restoring stiffness of TLP is derived with the set-down motion of platform and the coupled motion of the tension leg and platform. The results in this paper indicates that typhoon has a major impact on the safety of the platform in production operation, and it is also a threat to the strength of tension legs and risers.

Coupled Dynamic Analysis of a Tension Leg Platform Floating Offshore Wind Turbine

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Teng Wang ◽  
Hui Jin ◽  
Xiaoni Wu
Keyword(s):  
Dynamic Analysis ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Wind Loads ◽  
Offshore Wind Turbine ◽  
Wave Loads ◽  
Tension Leg Platform ◽  
Floating Offshore Wind Turbine ◽  
Turbulent Wind ◽  
Coupled Dynamic Analysis

The dynamic response of a tension leg platform (TLP) floating offshore wind turbine (FOWT) was analyzed with considering the aero-hydro characteristic of the whole floating wind turbine system including the wind turbine, TLP platform, and tethers. The “aero-hydro” coupled dynamic analysis was conducted in ansys-aqwa with a dynamic link library (DLL) calculating the aerodynamics loading at every steptime based on the blade element momentum theory. Results from the coupled dynamic analysis of TLP FOWT under the condition of turbulent wind and regular wave show that the wind loads influence mainly the low-frequency response of the TLP FOWT. The wind loads have a large impact on the offsets of the TLP away from the initial position while the wave loads influence mainly the fluctuation amplitude of the TLP FOWT. The average TLP pitch response under the wind load is significantly larger due to the large wind-induced heeling moment on the wind turbine. In addition, the tension of tethers at the upwind end is greater than that at the downwind end. The wind loads could reduce effectively the average tension of the tethers, and the tension of tethers is significantly affected by the pitch motion. Results from the coupled dynamic analysis of TLP FOWT under the condition of turbulent wind and irregular wave show that the surge and pitch of TLP result in an obvious increase of thrust of the turbine and the amplitude of torque fluctuation, more attention should be paid to the pitch and surge motion of TLP FOWT.

scholarly journals AGED ASPHALTIC DIKE REVETMENTS ON (SATURATED) SAND TESTED IN A LARGE DELTAFLUME

2018 ◽  
pp. 3
Author(s):  
Bernadette Wichman ◽  
Mark Klein Breteler ◽  
Arjan De Looff ◽  
Jan Hateboer
Keyword(s):  
The Netherlands ◽  
Wave Height ◽  
Significant Wave Height ◽  
Repeated Loading ◽  
Wave Loads ◽  
Saturated Sand ◽  
Significant Wave ◽  
Sand Body ◽  
Sea Dikes

In the Netherlands, 600 km of the sea dikes are protected by an asphaltic revetment which must resist considerable wave loads with a significant wave height of up to 4.5 m. The subsoil is normally sandy, and the asphalt layer can fail as a result of fatigue due to repeated loading under storm conditions (Wichman & Davise 2016). Fifty years old asphalt has been taken from the Dutch Lauwersmeer dike and placed on a sand body in the large Deltaflume at Deltares, where it is possible to generate large waves (up to 4 meters). It is still unsure how the asphalt will fail, while interacting with the sandy subsoil, depending on the position of the phreatic line, among other factors.

scholarly journals DINAMIKA KENDARAAN JALAN LURUS 3 PADA GEROBAK LISTRIK PENGANGKUT SAMPAH KAPASITAS 2 m3

POROS ◽  
2017 ◽  
Vol 12 (1) ◽  
pp. 18
Author(s):  
Edward Suhartono ◽  
G Soeharsono ◽  
Danardono Agus Sumarsono
Keyword(s):  
Dynamic Analysis ◽  
Maximum Velocity ◽  
Vehicle Dynamic ◽  
Garbage Disposal ◽  
Tractive Effort ◽  
Analytical Result ◽  
Cart Model ◽  
Human Powered ◽  
Maximum Inclination ◽  
Do So

Abstract: A residential dump transport to a temporary garbage disposal medium using a human-powered dump cart is not humane. An electrical-powered propulsion system can be one of the eco-friendly system which can be implemented to the cart, thus substitutes the human’s role to do so. This propulsion is analyzed by using vehicle dynamic analysis. Vehicle dynamic analysis which is conducted, discuss tractive effort which overcomes resistances during vehicle’s movement and accelerates the vehicle, and specification of drive train, used to drive it. Based on analytical result, it is obtained an electric dump cart model which can move at a 25 km/h maximum velocity, 20° maximum inclination while it is empty loaded, and 10° maximum inclination while it is fully loaded. 

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.

Slug Flow and Waves Induced Motions in Flexible Riser

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Arturo Ortega ◽  
Ausberto Rivera ◽  
Carl M. Larsen
Keyword(s):  
Dynamic Analysis ◽  
Slug Flow ◽  
Distributed Simulation ◽  
Coupled Analysis ◽  
Induced Response ◽  
Element Formulation ◽  
Wave Loads ◽  
Flexible Riser ◽  
Two Phase ◽  
Slender Structure

Flexible risers provide optimum solutions for deep water offshore fields. Reliable dynamic analysis of this kind of slender structure is crucial to ensure safety against long time fatigue failure. Beyond the effects from wave loads, the influence from transient internal slug flow on the slender structure dynamics should also be taken into account. In this study, two coupled in-house codes were used in order to identify and quantify the effects of an internal slug flow and wave loads on the flexible riser dynamics. One code carries out a global dynamic analysis of the slender structure displacements using a finite element formulation. The other program simulates the behavior of the internal slug flow using a finite volume method. The slug flow is influenced by the dynamic shape of the riser, while the time varying forces from internal slug flow plus external waves will influence the shape. Hence, a fully coupled analysis is needed in order to solve the coupled problem. By means of the distributed simulation, these two programs run synchronously and exchange information during the time integration process. A test case using hydrodynamic forces according to the linear Airy wave theory coupled with an internal unstable slug flow was analyzed and the results shown amplification of the dynamic response due to the interaction between the two load types, effects on the effective tension caused by the internal two-phase flow, and influence on the internal slug flow caused by the wave-induced response.

scholarly journals Propulsion Performance Analysis of Wave-powered Boats

2020 ◽  
Vol 10 (2) ◽  
pp. 121-129
Author(s):  
Zong-Yu Chang ◽  
Chao Deng ◽  
Jia-Kun Zhang ◽  
Zhan-Xia Feng ◽  
Zhong-Qiang Zheng
Keyword(s):  
Wave Height ◽  
State Level ◽  
Sea State ◽  
Torsion Spring ◽  
Propulsion Performance ◽  
Long Duration ◽  
Level 1 ◽  
Heave Motion ◽  
The Relationship ◽  
Restoring Stiffness

With the development of oceanographic research and marine environment protection, mobile marine platforms are applied for ocean observation for a long journey. Wave-powered boats are capable of applying wave motion to propel itself and make a long-duration survey. This paper presents the dynamics of the wave-powered boat under the excitation of the heave motion and pitch motion. Taking the wave-powered boat with double fins as an example, the heave and pitch motions of the boat are obtained by ANSYS-AQWA firstly. Then the relationship between propulsion performance and three factors, including  wave height, wave period, and restoring stiffness of torsion spring, was analyzed through multibody dynamics software ADAMS. With the increase of sea state from level 1 to level 4 the average propulsion speed increased from 0.4m/s to 1.4m/s. Under the same wave height and period, with the increase of restoring stiffness of torsion spring from 0.0125N·m/deg to 0.3N·m /deg, the propulsion speed of the wave-powered boat increases first and then decreases, and there exists an optimum stiffness. Through the calculation it is found that when the restoring stiffness of torsional spring is increased from 0.025N·m /deg to 0.2N·m /deg with the sea state level 1 to 4, the wave powered boat has better propulsion performance.

scholarly journals STUDY ON THE FAST MISSILE CRAFT OF 60 M ON THE SEASTATE CONDITION OF THE WEST AND EASTERN INDONESIAN WATER

2017 ◽  
Vol 11 (3) ◽  
pp. 239-250
Author(s):  
Soegeng Hardjono
Keyword(s):  
South China Sea ◽  
Statistical Methods ◽  
Wave Height ◽  
South China ◽  
Empirical Formula ◽  
The South China Sea ◽  
Extreme Wave ◽  
The West ◽  
Maximum Wave Height ◽  
The North

Recently, Indonesian Navy is developing warship fleet by constructing Fast Missile Craft (KCR) 60M. The performance of KCR 60M  depends on the wave height of Indonesian waters. It needs to perform research on the maximum wave height for the ship length of KCR 60M and the minimum ship length of KCR 60M to cope with the highest extrem waves by statistical methods and empirical formula. The analysis result shows that KCR 60M can operate at a maximum wave height of 4,73m. Since the wave height of Indonesian water is less than 4,73m, then KCR 60M can operate throughout the year, except in Desember and January in the North areas of Indonesia near the South China Sea border due to the moonsun Asia. However, the existency of the extrem wave height >4,3m cause KCR 60M unable to operate whether in the North or South Equators as well as Inter-island waters. KCR 60M also unable to operate in the whole Naval Main Base (Lantamal) from Lantamal II (Padang) up to Lantamal XIV (Sorong). Based on the average extreme wave height of 5,1m, it can be determined that KCR 60M capable of operating has a minimum ship length of about 70m.

scholarly journals MISALIGNMENT AND LAG TIME OF WIND AND WAVE OCCURRENCE BASED ON 10 YEARS MEASUREMENTS IN THE NORTH SEA NEAR THE GERMAN COAST

2018 ◽  
pp. 13
Author(s):  
Arndt Hildebrandt ◽  
Remo Cossu
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
North Sea ◽  
Offshore Wind ◽  
Wave Loads ◽  
Wind Speeds ◽  
The North ◽  
The North Sea ◽  
The Impact ◽  
The Waves

There are several intentions to analyze the correlation of wind and wave data, especially in the North Sea. Fatigue damage is intensified by wind and wave loads acting from different directions, due to the misaligned aerodynamic damping of the rotor regarding the wave loads from lateral directions. Furthermore, construction time and costs are mainly driven by the operational times of the working vessels, which strongly depend on the wind and wave occurrence and correlation. Turbulent wind can rapidly change its direction and intensity, while the inert water waves react slowly in relation to the wind profile. Tuerk (2008) investigates the impact of wind and turbulence on offshore wind turbines by analyzing data of four years. The study shows that the wave height is increasing with higher wind speeds but when the wind speed drops the reaction of the waves is postponed. The dependence of the wave height on the wind speed is varying because of the atmospheric stability and different wind directions. Fischer et al. (2011) estimated absolute values of misalignment between wind and waves located in the Dutch North Sea. The study presents decreasing misalignment for increasing wind speeds, ranging up to 90 degrees for wind speeds below 12 m/s and up to 30 degrees for wind speeds above 20 m/s. Bredmose et al. (2013) present a method of offshore wind and wave simulation by using metocean data. The study describes characteristics of the wind and wave climate for the North and Baltic Sea as well as the directional distribution of wind and waves. Güner et al. (2013) cover the development of a statistical wave model for the Karaburun coastal zone located at the southwest coast of the Black Sea with the help of wind and wave measurements and showed that the height of the waves is directly correlating with the duration of the wind for the last four hours.

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