Experimental Study on Wave-Induced Structural Responses of Semisubmersibles

1985 ◽  
Vol 107 (4) ◽  
pp. 461-466 ◽  
Author(s):  
T. Yoneya
Keyword(s):  
Experimental Study ◽  
Close Agreement ◽  
Experimental Studies ◽  
Scale Model ◽  
Test Model ◽  
Regular Waves ◽  
Structural Dynamic ◽  
Structural Dynamic Model ◽  
Structural Responses ◽  
Wave Induced

This paper describes experimental studies on the motion, mooring tension and structural responses of a typical semisubmersible in regular waves. A 1/50-scale structural dynamic model of two-pontoon type was made of acryl and the tank tests were carefully carried out. The measured platforms motions of the model were compared with calculations and close agreement was obtained. As to the structural responses the measured values of the test model agree approximately with the calculated results of a full-scale model. The close experimental results of structural responses presented here are expected to be valuable for the design of similar types of semisubmersibles.

Experimental Study on the Influence of Hull Spacing on Hard-Chine Catamaran Motions

2001 ◽  
Vol 45 (03) ◽  
pp. 216-227
Author(s):  
R. Centeno ◽  
K. S. Varyani ◽  
C. Guedes Soares
Keyword(s):  
Experimental Study ◽  
Cross Flow ◽  
Experimental Program ◽  
Two Dimensional ◽  
Regular Waves ◽  
Viscous Forces ◽  
Motion Responses ◽  
Resonance Frequencies ◽  
Flow Drag ◽  
Wave Induced

An experimental program was performed with hard-chine catamaran models in regular waves. The distance between the demi-hulls of the models was changed to assess its effects on the wave-induced motions. The results allowed the study of some aspects related to catamaran motions, like the interference between the hulls and resonance frequencies. The experimental results are compared with calculations performed with a recently developed code based on a two-dimensional potential flow theory in which viscous forces are included through a cross-flow drag approach. The effect of the hull distance in the heave and pitch motion responses and the importance of the viscous forces in such hull configurations are shown.

Dynamic Behavior of Submarine Pipelines Under Laying Operation

1982 ◽  
Vol 104 (4) ◽  
pp. 313-318 ◽  
Author(s):  
N. Suzuki ◽  
N. Jingu
Keyword(s):  
Experimental Study ◽  
Dynamic Behavior ◽  
Water Depth ◽  
Forced Oscillation ◽  
Bending Moment ◽  
Scale Model ◽  
Regular Waves ◽  
Wave Response ◽  
Dynamic Bending

Theoretical and experimental study on dynamic behavior of submarine pipelines under laying operation with articulated stingers is described in this paper. Wave response tests in regular waves and forced oscillation tests in still water were conducted using the 1/20 scale model of 406.4 mm o.d. (16 in. o.d.) pipeline laid in 150 m (500 ft) water depth. The results show that: 1) the maximum dynamic bending moment of pipeline MDmax occur at a stinger roller, 2) dynamic bending moment of pipelines MD at shorter periods are larger than those at longer periods, 3) the values of MD in an over-bend region depend highly upon stinger motion, 4) those of MD in a sag-bend region are less than MD max in an over-bend region, 5) the values of MD/HMY increase as the stinger volume increases and that 6) stinger motion at shorter periods are different from those at longer periods.

scholarly journals DEVELOPMENT OF PHYSICAL MODEL VEHICLE WITH REMOTIONAL CONTROL FOR EXPERIMENTAL STUDIES OF VEHICLE PROPERTIES

2020 ◽  
Vol 1 (46) ◽  
pp. 341-352
Author(s):  
Timkov O ◽  
◽  
Yashchenko D ◽  
Keyword(s):  
Mathematical Model ◽  
Experimental Study ◽  
Remote Control ◽  
Physical Model ◽  
Large Scale ◽  
Experimental Studies ◽  
Scale Model ◽  
Recording Equipment ◽  
Control Equipment ◽  
The Future

The article is devoted to the development of the physical model of the vehicle, the equipment of the measuring, recording and remote control equipment for the experimental study of the properties vehicles. The construction of the physical model and the used electronic modules is described in detail, references are given to the application libraries and the code of the first part of the program for remote control. In the future, it is planned to develop a mathematical model of the movement of a passenger vehicle and to check its adequacy in conducting experimental studies on maneuverability on a physical model. The aim of the article is developed the physical model of the vehicle, equipped with measuring, recording and remote control equipment, for the experimental study of the properties of vehicle. Materials and research methods: development and designing (experimental research of properties of vehicles on the physical model); remote control; wheeled controlled module. The self-propelled large-scale model of the vehicle, reproducing a passenger car of the category M1, with a controlled wheelbase and a rear drive axle, has been developed. The model is equipped with the necessary measuring and recording equipment and remote control equipment. The software of the model allows you to implement both control manual and the given algorithm. In the future, it is planned to develop a mathematical model of the vehicle motion and to check its adequacy on the developed physical model. The obtained results will allow to improve not only the mathematical model, but also the experimental physical model and proceed further to the study of the properties of hybrid road trains with an active trailer link. KEY WORDS: VEHICLE, PHYSICAL MODEL, EXPERIMENT, STUDY, MODULE, MEMORY CARD, ACCELEROMETER, PROGRAM.

scholarly journals Hydrodynamic Performance of a Hybrid System Combining a Fixed Breakwater and a Wave Energy Converter: An Experimental Study

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5740
Author(s):  
Wei Peng ◽  
Yingnan Zhang ◽  
Xueer Yang ◽  
Jisheng Zhang ◽  
Rui He ◽  
...  
Keyword(s):  
Experimental Study ◽  
Hybrid System ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Scale Model ◽  
Wave Power ◽  
Energy Converter ◽  
Power Extraction ◽  
Wave Induced

In this paper, a hybrid system integrating a fixed breakwater and an oscillating buoy type wave energy converter (WEC) is introduced. The energy converter is designed to extract the wave power by making use of the wave-induced heave motions of the three floating pontoons in front of the fixed breakwater. A preliminary experimental study is carried out to discuss the hydrodynamic performance of the hybrid system under the action of regular waves. A scale model was built in the laboratory at Hohai University, and the dissipative force from racks and gearboxes and the Ampere force from dynamos were employed as the power take-off (PTO) damping source. During the experiments, variations in numbers of key parameters, including the wave elevation, free response or damped motion of the floating pontoons, and the voltage output of the dynamos were simultaneously measured. Results indicate that the wave overtopping and breaking occurring on the upper surfaces of floating pontoons have a significant influence on the hydrodynamic performance of the system. For moderate and longer waves, the developed system proves to be effective in attenuating the incident energy, with less than 30% of the energy reflected back to the paddle. More importantly, the hydrodynamic efficiency of energy conversion for the present device can achieve approximately 19.6% at the lowest wave steepness in the model tests, implying that although the WEC model harnesses more energy in more energetic seas, the device may be more efficient for wave power extraction in a less energetic sea-state.

Experimental Study of Wave Induced Loads and Motions on FLNG in Head and Oblique Sea Waves

2016 ◽  
Author(s):  
Yuting Jin ◽  
Shuhong Chai ◽  
Jonathan Duffy ◽  
Christopher Chin ◽  
Neil Bose
Keyword(s):  
Experimental Study ◽  
Natural Gas ◽  
Numerical Solutions ◽  
Transfer Functions ◽  
Time History ◽  
Hydrodynamic Performance ◽  
Scale Model ◽  
Sea Waves ◽  
Hydrodynamic Behaviour ◽  
Wave Induced

In the past decade, an innovative concept, the floating liquefied natural gas (FLNG) system has been developed as a more effective solution over conventional pipelines for exploiting offshore natural gas resources. Understanding the hydrodynamic behaviour of such a mega structure in a real seaway is essential for determining its performance as well as evaluating the operabilities of on-board facilities and safe offloading. In this paper, experimental study on the hydrodynamic performance of a generic FLNG hull form has been presented. The 1:100 scale model was tested in the Australian Maritime College model test basin for head sea and oblique sea conditions at zero forward speed. The wave induced loads and motions were measured by load cells and linear variable differential transducers (LVDTs) respectively. Experimental uncertainties on each of the measured variables were studied by taking partial differentiations on the uncertainty sources. The time history measurements were decomposed by Fourier series for obtaining frequency domain force/moment and motion transfer functions. The results were compared with numerical solutions from potential flow and Reynolds-Averaged Navier-Stokes (RANS) solvers. A good correlation between the experimental and numerical results has been demonstrated.

Experimental study of the effect of wind above irregular waves on the wave-induced load statistics

2021 ◽  
pp. 103940
Author(s):  
Julie Caroee Kristoffersen ◽  
Henrik Bredmose ◽  
Christos Thomas Georgakis ◽  
Hubert Branger ◽  
Christopher Luneau
Keyword(s):  
Experimental Study ◽  
Irregular Waves ◽  
Wave Induced

Study on vertical motion reduction of a trimaran based on collaborative controlled appendages

2020 ◽  
Vol 17 (6) ◽  
pp. 172988142097677
Author(s):  
Zhilin Liu ◽  
Linhe Zheng ◽  
Guosheng Li ◽  
Shouzheng Yuan ◽  
Songbai Yang
Keyword(s):  
Experimental Study ◽  
Vertical Motion ◽  
Model Tests ◽  
Wave Period ◽  
Regular Waves ◽  
Towing Tank ◽  
Vertical Stability ◽  
Stabilization Control ◽  
Stability Performance

In recent years, the trimaran as a novel ship has been greatly developed. The subsequent large vertical motion needs to be studied and resolved. In this article, an experimental study for a trimaran vertical stabilization control is carried out. Three modes including the bare trimaran (the trimaran without appendages, the trimaran with fixed appendages, and the trimaran with controlled appendages) are performed through model tests in a towing tank. The model tests are performed in regular waves. The range of wave period is 2.0–4.0 s, and the speed of the carriage is 2.93 and 6.51 m/s. The results of the three modes show the fixed appendages and the actively controlled appendages are all effective for the vertical motion reduction of the trimaran. Moreover, the controlled appendages are more effective for the vertical stability performance of the trimaran.

Model Test and Numerical Analysis of an Offshore Bottom Fixed Pentapod Wind Turbine Under Seismic Loads

2016 ◽  
Author(s):  
Wenhua Wang ◽  
Zhen Gao ◽  
Xin Li ◽  
Torgeir Moan ◽  
Bin Wang
Keyword(s):  
Wind Turbine ◽  
Wind Wave ◽  
Seismic Analysis ◽  
Wind Farms ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Test Model ◽  
Structural Dynamic ◽  
Load Conditions

In the last decade the wind energy industry has developed rapidly in China, especially offshore. For a water depth less than 20m, monopile and multi-pile substructures (tripod, pentapod) are applied widely in offshore wind farms. Some wind farms in China are located in high seismicity regions, thus, the earthquake load may become the dominant load for offshore wind turbines. This paper deals with the seismic behavior of an offshore wind turbine (OWT) consisting of the NREL 5MW baseline wind turbine, a pentapod substructure and a pile foundation of a real offshore wind turbine in China. A test model of the OWT is designed based on the hydro-elastic similarity. Test cases of different load combinations are performed with the environmental conditions generated by the Joint Earthquake, Wave and Current Simulation System and the Simple Wind Field Generation System at Dalian University of Technology, China, in order to investigate the structural dynamic responses under different load conditions. In the tests, a circular disk is used to model the rotor-nacelle system, and a force gauge is fixed at the center of the disk to measure the wind forces during the tests. A series of accelerometers are arranged along the model tower and the pentapod piles, and strain gauges glued on the substructure members are intended to measure the structural dynamic responses. A finite element model of the complete wind turbine is also established in order to compare the theoretical results with the test data. The hydro-elastic similarity is validated based on the comparison of the measured dynamic characteristics and the results of the prototype modal analysis. The numerical results agree well with the experimental data. Based on the comparisons of the results, the effect of the wind and sea loads on the structural responses subjected to seismic is demonstrated, especially the influence on the global response of the structure. It is seen that the effect of the combined seismic, wind, wave and current load conditions can not be simply superimposed. Hence the interaction effect in the seismic analysis should be considered when the wind, wave and current loads have a non-negligible effect.

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