Conceptual Design and Model Tests for a Mid-Water Floating Hyperloop Tunnel

2020 ◽  
Author(s):  
L. J. Kemp ◽  
W. J. Otto ◽  
O. J. Waals
Keyword(s):  
Conceptual Design ◽  
High Speed ◽  
Optical Measurement ◽  
Model Tests ◽  
Scale Model ◽  
Mooring Line ◽  
Mooring System ◽  
Tunnel Length ◽  
Greenhouse Gasses ◽  
Global Emission

Abstract Aviation has a significant impact on the global emission of greenhouse gasses. On the Northern Atlantic route alone there are over 2,500 crossings daily. This illustrates the high demand for connecting people. It is expected that this demand will only increase in the future, which will increase the emissions due to aviation even further. An alternative way for connecting people can be the hyperloop, which obtains comparable speeds while using a fraction of the energy. For intercontinental connections a tunnel would be necessary. In this study, a conceptual design of a mid-water floating hyperloop tunnel is made and tested on model scale at MARIN. In the present paper the results are discussed of model tests on a mid-water floating tunnel in Atlantic storm conditions at various wave directions and tunnel depths. The conceptual design of the tunnel is based on (nearly) available technology. One kilometer tunnel segments with a diameter of 11 m are connected to construct a tunnel length of > 5,000 km. Model basin tests are performed on scale 1:110, where a scale model of 140 m length is tested. The tunnel is designed as a neutral buoyant tunnel to reduce complexity and costs for the mooring system. The motions, deformations and mooring line tensions for the tunnel segments are measured by force transducers, accelerometers and an optical measurement system. Due to flexibility of the slender tunnel segments in combination with a soft mooring system, the tunnel tends to following the incoming waves for certain tunnel depths and wave directions. Only small motions and deformations are allowed for a hyperloop capsule to travel on high speed. The conceptual tests show first results on tunnel depth, structural and geometrical design of an hyperloop tunnel and mooring system.

Coupled Mooring Analysis and Large Scale Model Tests on a Deepwater Calm Buoy in Mild Wave Conditions

2002 ◽  
Author(s):  
T. H. J. Bunnik ◽  
G. de Boer ◽  
J. L. Cozijn ◽  
J. van der Cammen ◽  
E. van Haaften ◽  
...  
Keyword(s):  
Model Tests ◽  
Irregular Waves ◽  
Scale Model ◽  
Mooring Line ◽  
Wave Forces ◽  
Mooring System ◽  
Mooring Lines ◽  
Pitch Moment ◽  
Numerical Tool ◽  
Decay Tests

This paper describes a series of model tests aimed at gaining insight in the tension variations in the export risers and mooring lines of a CALM buoy. The test result were therefore not only analysed carefully, but were also used as input and to validate a numerical tool that computes the coupled motions of the buoy and its mooring system. The tests were carried out at a model scale of 1 to 20. Captive tests in regular and irregular waves were carried out to investigate non-linearities in the wave forces on the buoy for example from the presence of the skirt. Decay tests were carried out to determine the damping of the buoy’s motions and to obtain the natural periods. Finally, tests in irregular waves were carried out. The dynamics of the mooring system and the resulting damping have a significant effect on the buoy’s motions. A numerical tool has been developed that combines the wave-frequency buoy motions with the dynamical behaviour of the mooring system. The motions of the buoy are computed with a linearised equation of motion. The non-linear motions of the mooring system are computed simultaneously and interact with the buoy’s motions. In this paper, a comparison is shown between the measurements and the simulations. Firstly, the wave forces obtained with a linear diffraction computation with a simplified skirt are compared with the measured wave forces. Secondly, the numerical modelling of the mooring system is checked by comparing line tensions when the buoy moves with the motion as measured in an irregular wave test. Thirdly, the decay tests are simulated to investigate the correctness of the applied viscous damping values. Finally, simulations of a test in irregular waves are shown to validate the entire integrated concept. The results show that: 1. The wave-exciting surge and heave forces can be predicted well with linear diffraction theory. However, differences between the measured and computed pitch moment are found, caused by a simplified modelling of the skirt and the shortcomings of the diffraction model. 2. To predict the tension variations in the mooring lines and risers (and estimate fatigue) it is essential that mooring line dynamics are taken into account. 3. The heave motions of the buoy are predicted well. 4. The surge motions of the buoy are predicted reasonably well. 5. The pitch motions are wrongly predicted.

Contribution of the Mooring System to the Low-Frequency Motions of a Semisubmersible in Combined Wave and Current

2009 ◽  
Author(s):  
Amany M. A. Hassan ◽  
Martin J. Downie ◽  
Atilla Incecik ◽  
R. Baarholm ◽  
P. A. Berthelsen ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Damping Ratio ◽  
Low Frequency ◽  
Scale Model ◽  
Mooring Line ◽  
Mooring System ◽  
Current Field ◽  
Mooring Lines ◽  
Mean Values ◽  
Low Frequency Motion

This paper presents the results of an experiment carried out on a semi-submersible model to measure the steady drift force and low frequency surge motions. In the experiments, the influence of mooring systems was also investigated in different combinations of current and sea state. The measurements were carried out with a 1/50 scale model which was moored using horizontal springs and catenary mooring lines. A comparative study of the mean values of steady drift motions and the standard deviation of the low frequency motion amplitudes is presented. In addition, the effect of current on the damping ratio is discussed. It is found that for both horizontal and catenary moorings, the presence of a current increases the damping ratio of the system. For the catenary mooring system, as expected, the presence of mooring lines and their interaction with waves and current increases the damping compared to the damping of the horizontal mooring system. The measured mean values of the surge motions in a wave–current field are compared to the superposed values of those obtained from waves and current separately. For the horizontal mooring, it is found that there is good agreement in moderate sea states, while in higher sea states the measured motion responses are larger. In the wave-current field, the standard deviation of the surge motion amplitudes is found to be less than that obtained in waves alone. This can be explained by the increased magnitude of the damping ratio. Only in the cases of high sea states with the horizontal mooring system, was it found that the standard deviation of the surge motions is slightly larger than those obtained for waves and current separately. This may be explained by the absence of catenary mooring line damping.

Coupled Mooring Analysis for a Deep Water CALM Buoy

2004 ◽  
Author(s):  
J. L. Cozijn ◽  
T. H. J. Bunnik
Keyword(s):  
Model Tests ◽  
Mooring Line ◽  
Mooring System ◽  
Test Results ◽  
Mooring Lines ◽  
Restoring Force ◽  
Small Water ◽  
Force Components ◽  
Force Characteristics ◽  
Line Loads

The effect of the mooring loads on floator motions can be significant for small water plane are floaters like CALM buoys. Not only does the mooring system contribute to the static restoring force components, but the dynamic behaviour of the mooring lines also affects the inertia and damping of the moored CALM buoy. The results from model tests with a moored CALM buoy were compared with the results from two series of time-domain computer simulations. First, fully dynamic coupled simulations were carried out, in which the interaction between the floater motions and the dynamic mooring line loads was modelled for all 6 modes of motion. Second, quasi-static simulations were carried out, in which only the (non-linear) static restoring force characteristics of the mooring system were taken into account. The comparison of results from the simulations and the model tests clearly indicates that the fully dynamic coupled simulations show a much better correspondence with the model test results than the quasi-static simulations. It is concluded that for the simulation of the behavior of a moored CALM buoy in waves a fully dynamic coupled mooring analysis is essential.

Experimental and Numerical Study on Large Truncation of Deepwater Mooring Line

2009 ◽  
Author(s):  
Yihua Su ◽  
Jianmin Yang ◽  
Longfei Xiao ◽  
Gang Chen
Keyword(s):  
Dynamic Response ◽  
Water Depth ◽  
Numerical Study ◽  
Unit Length ◽  
Low Frequency ◽  
Model Tests ◽  
Mooring Line ◽  
Mooring System ◽  
Mooring Lines ◽  
Wave Basin

Modeling the deepwater mooring system in present available basin using standard Froude scaling at an acceptable scale presents new challenges. A prospective method is to truncate the full-depth mooring lines and find an equivalent truncated mooring system that can reproduce both static and dynamic response of the full-depth mooring system, but large truncation arise if the water depth where the deepwater platform located is very deep or the available water depth of the basin is shallow. A Cell-Truss Spar operated in 1500m water depth is calibrated in a wave basin with 4m water depth. Large truncation arises even though a small model scale 1:100 is chosen. A series of truncated mooring lines are designed and investigated through numerical simulations, single line model tests and coupled wave basin model tests. It is found that dynamic response of the truncated mooring line can be enlarged by using larger diameter and mass per unit length in air. Although the truncated mooring line with clump presents a “taut” shape, its dynamic characteristics is dominated by the geometry stiffness and it underestimates dynamic response of the full-depth mooring line, even induces high-frequency dynamic response. There are still two obstacles in realizing dynamic similarity for the largely truncated mooring system: lower mean value of the top tension of upstream mooring lines, and smaller low-frequency mooring-induced damping.

Hybrid Verification of a Deepwater FPSO Using Truncated Model Tests and Numerical Simulations

2021 ◽  
Author(s):  
Xiangbo Liu ◽  
Ching Theng Liong ◽  
Nitesh Kumar ◽  
Kie Hian Chua ◽  
Allan Ross Magee ◽  
...  
Keyword(s):  
Numerical Model ◽  
Numerical Modelling ◽  
Water Depth ◽  
Return Period ◽  
Line Length ◽  
Model Tests ◽  
Mooring Line ◽  
Mooring System ◽  
Test Results ◽  
Set Up

Abstract This paper presents verification of a deep water FPSO with a semi-taut mooring system using model tests and numerical modelling commonly referred to as the hybrid method. The vessel under investigation is a FPSO of 310m in length and 47m in beam with an internal turret mooring system of 12 lines in 2000m water depth. Two configurations of the mooring systems i.e. inline and bisecting are investigated for sea-states up to 1000yr return period. A full depth mooring system has been developed for the FPSO and model tests will be carried out to verify the model. Due to limitations to the size of the model basins, the model tests will be carried out for a truncated mooring setup. Non-linear horizontal stiffness of a single mooring line and the complete mooring system with truncation is compared to that of the existing full depth mooring system. Discrepancies in the vertical forces due to truncation of line length will be discussed in the paper. A numerical model of the truncated set-up will be calibrated using model test results.

Analysis of the Tunnel Immersion for the Busan-Geoje Fixed Link Project Through Scale Model Tests and Computer Simulations

2009 ◽  
Author(s):  
Hans Cozijn ◽  
Jin Wook Heo
Keyword(s):  
Simulation Model ◽  
Computer Simulations ◽  
Time Domain ◽  
Extreme Values ◽  
Sensitivity Study ◽  
Model Tests ◽  
Direct Access ◽  
Scale Model ◽  
Mooring System ◽  
Sea Bed

In Korea a four lane motorway is constructed between the city of Busan and the island Geoje, reducing traveling times from 1 hour by ferry to just 10 minutes by car. The so-called Busan-Geoje Fixed Link consists of 2 cable-stayed girder bridges and a tunnel, crossing the bay of Jinhae. The submerged tunnel is built by transporting each of its 18 elements below 2 pontoons from a construction dock to their final positions and lowering them on the sea bed. The project is unique, because the tunnel elements are installed in a bay with direct access towards open sea. For this reason, the effects of incoming swells and wind seas were investigated in detail, so that the operational limits of the tunnel element immersion could be accurately determined. This was achieved by using an approach of combined hydrodynamic scale model tests and time-domain computer simulations. First, scale model tests were carried out in MARIN’s Shallow Water Basin. A detailed test set-up was constructed, including the trench in which the tunnel elements are placed, as is shown in the photograph. Models of a tunnel element, two pontoons, the mooring system, contraction lines and suspension wires were constructed at a scale of 1:50. The motions of the pontoons and the submerged tunnel element, as well as the tensions in the lines, were measured in a range of different wave conditions. Different stages of the tunnel immersion were investigated. Second, a simulation model of the pontoons and tunnel element was constructed in MARIN’s time-domain simulation tool aNySIM. The large number of mooring lines, contraction lines and suspension wires resulted in a relatively complex numerical model. The simulation model was calibrated such that the results from the model tests could be accurately reproduced. Subsequently, a sensitivity study was carried out, investigating the parameters most critical to the operation and the mooring system of the pontoons was further optimized. Finally, the operational limits of the tunnel immersion were evaluated by carrying out more than 6,500 time-domain simulations, investigating a large number of different combinations of wind sea and swell. The simulation results included motions, velocities and accelerations, as well as line tensions. The extreme values were used to perform a combined evaluation of more than 10 structural and operational criteria. The photograph below (copyright Peter de Haas, Royal Haskoning) shows the immersion of the first of 18 tunnel elements in the bay of Jinhae, in February 2008.

Experimental Investigation of Mooring Line Loading Using Large and Small-Scale Models

2000 ◽  
Vol 123 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Neil Kitney ◽  
David T. Brown
Keyword(s):  
Experimental Investigation ◽  
Large Scale ◽  
Model Tests ◽  
Scale Model ◽  
Mooring Line ◽  
Small Scale ◽  
The European Union ◽  
Single Chain ◽  
Mooring Lines ◽  
Highly Nonlinear

For catenary mooring lines, the relationship between excursion of the point of suspension and the length of suspended line is highly nonlinear. If the point of suspension is then set in motion, the velocity of the line resulting from a change in catenary profile induces additional nonlinear hydrodynamic loading components. The sensitivity of the mooring line to initial and oscillatory conditions results in a complicated tension history at the point of suspension, with line tensions possibly greatly exceeding those predicted by static analyses. This paper presents results from an experimental investigation into the response of a large (1:16) and small (1:70) scale single-chain catenary model mooring line when subject to a comprehensive, and equivalent, range of excitation parameters. Tests were performed at purpose-built test facilities. Small-scale model tests were carried out at University College London (UCL). Large-scale model mooring line tests were completed at the Ship Dynamics Laboratory, Canal de Experiencias Hidrodinamicas de El Pardo (CEHIPAR), Madrid, Spain. Funding for the model tests performed in Spain was provided through the European Union Access to Large Scale Facilities—Training and Mobilisation of Researchers Program.

scholarly journals Transient Responses Evaluation of FPSO with Different Failure Scenarios of Mooring Lines

2021 ◽  
Vol 9 (2) ◽  
pp. 103
Author(s):  
Dongsheng Qiao ◽  
Binbin Li ◽  
Jun Yan ◽  
Yu Qin ◽  
Haizhi Liang ◽  
...  
Keyword(s):  
Service Condition ◽  
Mooring Line ◽  
Mooring System ◽  
Transient Effects ◽  
Floating Platform ◽  
Transient Responses ◽  
Mooring Lines ◽  
Performance Deterioration ◽  
Steady State Responses ◽  
Influence Process

During the long-term service condition, the mooring line of the deep-water floating platform may fail due to various reasons, such as overloading caused by an accidental condition or performance deterioration. Therefore, the safety performance under the transient responses process should be evaluated in advance, during the design phase. A series of time-domain numerical simulations for evaluating the performance changes of a Floating Production Storage and Offloading (FPSO) with different broken modes of mooring lines was carried out. The broken conditions include the single mooring line or two mooring lines failure under ipsilateral, opposite, and adjacent sides. The resulting transient and following steady-state responses of the vessel and the mooring line tensions were analyzed, and the corresponding influence mechanism was investigated. The accidental failure of a single or two mooring lines changes the watch circle of the vessel and the tension redistribution of the remaining mooring lines. The results indicated that the failure of mooring lines mainly influences the responses of sway, surge, and yaw, and the change rule is closely related to the stiffness and symmetry of the mooring system. The simulation results could give a profound understanding of the transient-effects influence process of mooring line failure, and the suggestions are given to account for the transient effects in the design of the mooring system.

scholarly journals EXTREME WAVE PRESSURES AND LOADS ON A PILE-SUPPORTED WHARF DECK - INFLUENCES OF AIR GAP AND WAVE DIRECTION

2018 ◽  
pp. 5
Author(s):  
Andrew Cornett
Keyword(s):  
Offshore Structures ◽  
Model Tests ◽  
Scale Model ◽  
Extreme Waves ◽  
Wave Direction ◽  
Coastal Structures ◽  
Extreme Wave ◽  
Wave Impact ◽  
The Past ◽  
Water Depths

Many deck-on-pile structures are located in shallow water depths at elevations low enough to be inundated by large waves during intense storms or tsunami. Many researchers have studied wave-in-deck loads over the past decade using a variety of theoretical, experimental, and numerical methods. Wave-in-deck loads on various pile supported coastal structures such as jetties, piers, wharves and bridges have been studied by Tirindelli et al. (2003), Cuomo et al. (2007, 2009), Murali et al. (2009), and Meng et al. (2010). All these authors analyzed data from scale model tests to investigate the pressures and loads on beam and deck elements subject to wave impact under various conditions. Wavein- deck loads on fixed offshore structures have been studied by Murray et al. (1997), Finnigan et al. (1997), Bea et al. (1999, 2001), Baarholm et al. (2004, 2009), and Raaij et al. (2007). These authors have studied both simplified and realistic deck structures using a mixture of theoretical analysis and model tests. Other researchers, including Kendon et al. (2010), Schellin et al. (2009), Lande et al. (2011) and Wemmenhove et al. (2011) have demonstrated that various CFD methods can be used to simulate the interaction of extreme waves with both simple and more realistic deck structures, and predict wave-in-deck pressures and loads.

Large scale model tests on Royal Schelde SES

1989 ◽  
Author(s):  
R. DE GAAIJ ◽  
E. VAN RIETBERGEN ◽  
M. SLEGERS
Keyword(s):  
Large Scale ◽  
Model Tests ◽  
Scale Model ◽  
Large Scale Model
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