scholarly journals Ocean Engineering Basin at NMRI - Basis of and Model Test for Safety Evaluation

2014 ◽  
Vol 49 (3) ◽  
pp. 344-349
Author(s):  
Kazuhiro Yukawa
Keyword(s):  
Model Test ◽  
Safety Evaluation ◽  
Ocean Engineering

Identifying VIV Vibration Modes by Use of the Empirical Orthogonal Functions Technique

2002 ◽  
Author(s):  
Gudmund Kleiven
Keyword(s):  
Model Test ◽  
Vibration Mode ◽  
Multivariate Data ◽  
Empirical Orthogonal Functions ◽  
Mode Shapes ◽  
Data Sets ◽  
Vibration Modes ◽  
Ocean Engineering ◽  
Orthogonal Functions ◽  
Related Technique

The Empirical Orthogonal Functions (EOF) technique has widely being used by oceanographers and meteorologists, while the Singular Value Decomposition (SVD being a related technique is frequently used in the statistics community. Another related technique called Principal Component Analysis (PCA) is observed being used for instance in pattern recognition. The predominant applications of these techniques are data compression of multivariate data sets which also facilitates subsequent statistical analysis of such data sets. Within Ocean Engineering the EOF technique is not yet widely in use, although there are several areas where multivariate data sets occur and where the EOF technique could represent a supplementary analysis technique. Examples are oceanographic data, in particular current data. Furthermore data sets of model- or full-scale data of loads and responses of slender bodies, such as pipelines and risers are relevant examples. One attractive property of the EOF technique is that it does not require any a priori information on the physical system by which the data is generated. In the present paper a description of the EOF technique is given. Thereafter an example on use of the EOF technique is presented. The example is analysis of response data from a model test of a pipeline in a long free span exposed to current. The model test program was carried out in order to identify the occurrence of multi-mode vibrations and vibration mode amplitudes. In the present example the EOF technique demonstrates the capability of identifying predominant vibration modes of inline as well as cross-flow vibrations. Vibration mode shapes together with mode amplitudes and frequencies are also estimated. Although the present example is not sufficient for concluding on the applicability of the EOF technique on a general basis, the results of the present example demonstrate some of the potential of the technique.

The Investigation of Non-Linear Effect for a Circular Cylinder Shaped FPSO

2011 ◽  
Author(s):  
Sam-Kwon Hong ◽  
Rae-Hyoung Yuck ◽  
Beom-Seon Jang ◽  
Hi-Seok Kang ◽  
Se-Eun Kim ◽  
...  
Keyword(s):  
Circular Cylinder ◽  
Model Test ◽  
Ocean Waves ◽  
Ocean Engineering ◽  
Natural Period ◽  
Pitch Motion ◽  
Steel Catenary Riser ◽  
Engineering Research ◽  
Motion Performance ◽  
Plane Area

Nowadays, a circular cylinder shaped FPSO appears as a new type FPSO because it does not need the expensive turret system. A circular cylinder shaped FPSO has an excellent motion performance because pitch and roll natural periods are longer compared to traditional FPSO and heave natural period is also longer due to its small water plane area. Samsung heavy industries has developed a circular cylinder shaped FPSO called as S-Line. The feature of S-line has a shape cutting a groove around draft to reduce the water plane area. Through reducing water plane area, the heave natural frequency moves to lower frequency which is far from ocean waves. According to the results of a linear calculation by WAMIT, S-Line showed reduced vertical motion of heave, roll and pitch compared to conventional FPSO. But, S-Line showed unsuspected large pitch response in 1st model test which was carried out with horizontal mooring system by spring in SSMB (Samsung Ship Model Basin). It is conjectured that this large pitch response is caused by 2nd nonlinearity of the wave and/or parametric pitch phenomena. To verify the mooring load and improve the 2nd order pitch motion, model tests were carried out in SSMB and offshore basin of MOERI (Maritime & Ocean Engineering Research Institute) with two kinds of bilge box. This paper describes the nonlinear effect of 2nd order for pitch motion of a circular cylinder shaped FPSO based on model test and numerical simulation. As a result, S-Line developed by Samsung was also verified being able to use SCR (Steel Catenary Riser) due to its improved heave motion performance.

Experimental Study on Wave Loads of Flooded Ship

2007 ◽  
Author(s):  
B. W. Kim ◽  
D. C. Hong ◽  
S. Y. Hong ◽  
J. H. Kyoung ◽  
S. K. Cho ◽  
...  
Keyword(s):  
Model Test ◽  
Ship Motions ◽  
Test Model ◽  
Bending Moments ◽  
Wave Loads ◽  
Test Results ◽  
Ocean Engineering ◽  
Shear Forces ◽  
Engineering Research ◽  
Ship Model

This paper investigates wave loads of a flooded ship by model test. Model tests are performed in ocean engineering basin of MOERI (Maritime and Ocean Engineering Research Institute). Ship motions are measured by RODYM6D. Wave loads such as shear forces, bending moments and torsion moments are measured by ATI load cell mounted on segmented parts of the ship model. A 300 m-long barge ship with two flooded compartments is considered in model test. Responses of intact and flooded cases are compared. The test results are also compared with numerical analyses using boundary element method.

The Research of Moonpool Size Effect on the Hydrodynamic Performance of FDPSO

2011 ◽  
Author(s):  
Yuefeng Wei ◽  
Jianmin Yang ◽  
Gang Chen ◽  
Zhiqiang Hu
Keyword(s):  
Numerical Analysis ◽  
Size Effect ◽  
White Noise ◽  
Natural Frequency ◽  
Model Test ◽  
Hydrodynamic Performance ◽  
Ocean Engineering ◽  
Floating Platform ◽  
Paper Making ◽  
Reliable Model

FDPSO is a multifunction floating platform, which has the combined function of drilling, production, storage and offloading oil. The moonpool is necessary for drilling operation and the moonpool size effect will play a role on the hydrodynamic performance of FDPSO. A study of the moonpool size effect on such performance of FDPSO hull is presented in this paper, making use of numerical analysis and model tests techniques. The code WADAM is used for the hydrodynamic performance analysis. A model test aiming to validate the accuracy of the numerical analysis results was conducted in the Ocean Engineering basin in the State Key Laboratory of Ocean Engineering in the Shanghai Jiao Tong University. The model test included decaying test and white noise test. The decaying tests are performed in still water for heave, roll and pitch. White noise tests were carried out to obtain the RAO of FDPSO, with the wave incoming direction of 180° and 135°. The numerical results show a good agreement with the model test results, indicating a reliable model. The “piston” motion of the water inside the moonpool is significant, affecting the hydrodynamic performance of the FDPSO. The effect of moonpool size on the hydrodynamic performance of the FDPSO is analyzed through a numerical method. The relationship between the piston natural frequency of the water column inside the moonpool and its diameter and draft, are studied. An empirical formula of the “piston” natural frequency is proposed, and its validity is assessed.

Numerical and Model Test Investigation on the Motion Characteristic of FDPSO and the Sheltered Riser Vessel

2010 ◽  
Author(s):  
Yuefeng Wei ◽  
Zhiqiang Hu ◽  
Gang Chen ◽  
Jianmin Yang
Keyword(s):  
West Africa ◽  
Model Test ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Shielding Effect ◽  
Ocean Engineering ◽  
Floating Platform ◽  
Test Investigation ◽  
Moon Pool

FDPSO is a multifunction floating platform, capable of drilling, production, storage and offloading. Sheltered Riser Vessel (SRV) serves as an independent buoyant hull to provide riser tensions, which is situated in the moon pool of FDPSO. Due to the shielding effect of moon pool, the motion of SRV is very small, so as to meet the requirement of drilling. In order to validate the basic FDPSO and SRV concepts, a model test was conducted in the basin of Ocean Engineering in the State Key Lab of Ocean Engineering in Shanghai Jiao Tong University. The storm tests were carried out in wave extremes of West Africa and white noise wave environments. Potential theory was adopted to calculate the motion performance of FDPSO system. Frequency domain analysis of the motion response amplitude operator (RAO) and time domain analysis in the extreme sea condition are both conducted. The comparison between the numerical simulation and model test results shows that the results of RAO and statistical value of response time series in the extreme sea condition are coincident. It is indicate that the method is credible and the concepts of FDPSO and SRV are likely to be feasible in West Africa.

scholarly journals Numerical Research on Global Ice Loads of Maneuvering Captive Motion in Level Ice

2021 ◽  
Vol 9 (12) ◽  
pp. 1404
Author(s):  
Shenyu Xuan ◽  
Chengsheng Zhan ◽  
Zuyuan Liu ◽  
Qiaosheng Zhao ◽  
Wei Guo
Keyword(s):  
Model Test ◽  
Model Tests ◽  
Numerical Results ◽  
Test Results ◽  
Ocean Engineering ◽  
Drift Angle ◽  
Ice Loads ◽  
Level Ice ◽  
Turning Radius ◽  
Maneuvering Motion

In level ice, the maneuvering motion of icebreakers has a major influence on the global ice loads of the hull. This study researched the influences of the drift angle and turning radius on the ice loads of the icebreaker Xue Long through a partial numerical method based on the linear superposition theory of ice loads. First, with reference to the Araon model tests performed by the Korea Research Institute of Ships and Ocean Engineering (KRISO), numerical simulations of Araon’s direct motion were carried out at different speeds, and the average deviation between numerical results and model test results was about 13.8%. Meanwhile, the icebreaking process and modes were analyzed and discussed, compared with a model test and a full-scale ship trial. Next, the maneuvering captive motions of oblique and constant radius were simulated to study the characteristics of ice loads under different drift angles and turning radii. Compared with the maneuvering motion model tests in the ice tank of Tianjin University and the Institute for Ocean Technology of the National Research Council of Canada (NRC/IOT), the numerical results had good agreement with the model test results in terms of the variation trend of ice loads and ice–hull interaction, and the influences of drift angle and turning radius on ice resistance and transverse force, which have a certain reference value for sailing performance research and the design of the hull form of icebreaker ships, are discussed.

Dynamic Model Rupture Tests of Concrete Dams on Shaking Table

2012 ◽  
Vol 446-449 ◽  
pp. 2650-2655 ◽  
Author(s):  
Ming Ming Wang ◽  
Qiang Xu ◽  
Jian Yun Chen ◽  
Shao Lan Lv
Keyword(s):  
Dynamic Model ◽  
Model Test ◽  
Effective Means ◽  
Safety Evaluation ◽  
Model Material ◽  
Shaking Table ◽  
Observation Data ◽  
Ground Acceleration ◽  
Seismic Safety ◽  
University Of Technology

The seismic safety evaluation of dam is always concerned by designers and researchers. Due to the limited field prototype observation data, the dynamic model failure tests become more effective means than numerical analysis to investigate nonlinear dynamic response and failure mechanisms of concrete dam. A large number of the tests had been performed in Dalian university of technology in china. This paper makes a detailed description on the dynamic model test on shaking table. The similitude rules are discussed, the model material is introduced, the procedure is described for the dynamic model test. Based on the PGA(peak ground acceleration) inducing the first tension crack at the model dam body, the response of prototype dam under strong earthquake can be assessed by the test.

scholarly journals Comparison between Model Test and Three CFD Studies for a Benchmark Container Ship

2021 ◽  
Vol 9 (1) ◽  
pp. 62
Author(s):  
Ana-Maria Chiroșcă ◽  
Liliana Rusu
Keyword(s):  
Free Surface ◽  
Comparative Analysis ◽  
Viscous Flow ◽  
Model Test ◽  
Experimental Tests ◽  
Numerical Approach ◽  
Transport Systems ◽  
Container Ship ◽  
Test Results ◽  
Ocean Engineering

An alternative to experiments is the use of numerical model tests, where the performances of ships can be evaluated entirely by computer simulations. In this paper, the free surface viscous flow around a bare hull model is simulated with three Computational Fluid Dynamics (CFD) software packages (FINE Marine, ANSYS CFD and SHIPFLOW) and compared to the results obtained during the experimental tests. The bare hull model studied is the Duisburg Test Case (DTC), developed at the Institute of Ship Technology, Ocean Engineering and Transport Systems (ISMT) for benchmarking and validation of the numerical methods. Hull geometry and model test results of resistance, conducted in the experimental facility at SVA Postdam, Nietzschmann, in 2010, are publicly available. A comparative analysis of the numerical approach and experimental results is performed, related to the numerical simulation of the free surface viscous flow around a typical container ship. Further, a comparative analysis between the results provided by NUMECA, ANSYS and SHIPFLOW is performed. Regarding the solution obtained, a satisfactory agreement between the towing test results and the computation results can be noticed. The minimum mean error was obtained through the SHIPFLOW case, 2.011%, which proved the best solution for the case studied.

Numerical Modeling Practice and Verification of the Wind Load Estimation for FPSO and Semi-Submersible

2019 ◽  
Author(s):  
SeongMo Yeon ◽  
Hyunchul Jang ◽  
Jang Whan Kim ◽  
JooSung Kim ◽  
Bo Woo Nam ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Model Test ◽  
Wind Profile ◽  
Domain Size ◽  
Wind Load ◽  
Computational Domain ◽  
Ocean Engineering ◽  
Blind Test ◽  
Floating Structures ◽  
Modeling Practice

Abstract This paper summarizes a joint effort, TESK JDP, initiated by TechnipFMC, ExxonMobil Upstream Research Company (EMURC), Samsung Heavy Industries (SHI) and Korea Research Institute of Ships & Ocean Engineering (KRISO) in order to develop reliable modeling practices for the application of Computational Fluid Dynamics (CFD) to the design of the offshore floating structures. The modeling practice for the wind load on offshore floating structures, which was one of the topics in this JDP, was studied and verified against model test results. The wind load on the offshore floating structures mostly depends on the shape of the wind profile rather than the design wind speed. Much weight is put on the generation and retainment of the wind profile within the computational domain. The modeling practice for generating the wind profile referred to as sustainable atmospheric boundary layer (ABL) or horizontally homogeneous turbulent boundary layer (HHTBL) as well as domain size, mesh strategy, turbulence model are used to perform wind load simulations for a semi-submersible and FPSO respectively as a blind test between JDP members. In order to minimize uncertainties from geometric similarity, special care was taken during the simulation and model test for the FPSO due to the complicated top side modules. Given the modeling practice, the results are compared between JDP members and show consistent tendency. Also, a good agreement was observed for the hydrodynamic coefficients of the wind load for both the FPSO and semi-submersible.

1:52 Scale Testing of the First US Commercial Scale Floating Wind Turbine, VolturnUS: Testing Overview and the Evolution of Scale Model Testing Methods

2017 ◽  
Author(s):  
Matthew J. Fowler ◽  
Andrew J. Goupee ◽  
Christopher Allen ◽  
Anthony Viselli ◽  
Habib Dagher
Keyword(s):  
Model Test ◽  
Wind Wave ◽  
Model Testing ◽  
Model Tests ◽  
Scale Model ◽  
Test Facility ◽  
Ocean Engineering ◽  
Floating Platform ◽  
Design Validation ◽  
Floating Offshore Wind Turbines

Over the past 6 years, the University of Maine (UMaine) has been an active contributor in research and scale-model testing of floating offshore wind turbines (FOWTs). This paper serves to share the evolution of UMaine’s scale-model testing pedigree by exploring the various test campaigns at a high level, culminating with the design validation of the VolturnUS floating platform. These model test campaigns have each provided key insights into the behavior of FOWT platforms as well as improving the ability to perform model tests of FOWTs. In 2011, the UMaine-led DeepCwind Consortium carried out 1/50-scale model tests of a generic tension leg platform (TLP), a semi-submersible (semi), and a spar-buoy (spar) floating platform at the Maritime Research Institute Netherlands (MARIN) test facility. The designs were Froude-scaled and supported a scaled version of the 5-MW National Renewable Energy Laboratory (NREL) offshore research turbine. Data from these tests has been used extensively for numerical simulation validation efforts using NREL’s computer-aided engineering software FAST and laid the foundation for UMaine’s design efforts on VolturnUS. In 2013, UMaine conducted another test campaign at MARIN using the original semi-submersible from 2011 with an improved turbine as well as a 1:50-scale model of the VolturnUS concrete semi-submersible design. The improved DeepCwind semi-submersible data is currently being utilized in the validation of a large number of other analysis codes as part of the International Energy Agency’s OC5 project. In 2015, UMaine opened its own Wind/Wave test facility, the Alfond Wind/Wave Ocean Engineering Laboratory (W2). Utilizing this new facility, UMaine tested the 1:50-scale model DeepCwind semi-submersible, repeating the tests from MARIN, to validate the experimental equipment and procedures as well as demonstrate the capability of the W2. In 2016 UMaine carried out testing of a 1:52-scale model of the 100% design of the VolturnUS with a 6-MW topside as a final design validation to support the US Department of Energy-supported, full-scale Aqua Ventus demonstration project scheduled to be connected to the grid in 2019. A newly designed 6-MW scale model turbine was used in this test and the performance-matched turbine design methodology is described. Selected results from the test campaign and preliminary numerical comparisons are discussed as well as key lessons learned from the model test campaigns are presented.

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