Determination of Parameters Describing the Risk Areas of Ships Chaotic Rolling on the Example of LNG Carrier and OSV Vessel

Guze, S.; Wawrzyński, Wojciech; Wilczyński, Przemysław

doi:10.3390/jmse8020091

Cited by 8 publications

(4 citation statements)

References 25 publications

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“…On the other hand for the high loading conditions [2, 3, 4, 8 and 9] (Figure 11b-d,h,i) the damping coefficient show an inflection point nearly at the roll angle amplitude 10 • followed by an increase. It should be noted that the change in dampening at higher filling levels [2,3,4,8], is solely due to the increase in liquid cargo and thus liquid cargo motion, since the volume displacement is only changed in condition 9.…”

Section: Effect Of Liquid Cargomentioning

confidence: 99%

“…Roll motion is the most dangerous motion amongst the six degrees of freedom because it can lead to capsizing [1,2], causes crew discomfort, and thus reduce the vessel's efficiency [3]. Roll motion is especially critical for offshore floating vessels such as Floating Production Storage and Offloading (FPSO) units because they are expected to operate at a location for extended duration and as such cannot avoid severe weather conditions.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Determination of Non-Linear Roll Damping of an FPSO Pure Roll Coupled with Liquid Sloshing in Two-Row Tanks

Igbadumhe

Sallam

Fürth

et al. 2020

JMSE

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Wave excited roll motion poses danger for moored offshore vessels such as Floating Production Storage and Offloading (FPSO) because they cannot divert to avoid bad weather. Furthermore, slack cargo tanks are almost always present in FPSOs by design. These pose an increased risk of roll instability due to the presence of free surfaces. The most common method of determining roll damping is roll decay tests, yet very few test have been performed with liquid cargo, and most liquid cargo experiments use tanks that span the entire width of the vessel; which is seldom the case for full scale FPSO vessels during normal operations. This paper presents a series of roll decay test carried out on a FPSO model with two two-row-prismatic tanks with different filling levels. To directly investigate the coupling between the liquid sloshing and the vessel motion, without modifying the damping, tests were performed at a constant draft. The equivalent linear roll damping coefficients consisting of linear, quadratic and cubic damping terms are analyzed for each loading condition using four established methods, the Quasi-linear method, Froude Energy method, Averaging method and the Perturbation method. The results show that the cubic damping term is paramount for FPSOs and at low filling levels, were the FPSO is more damped. Recommendations regarding the applicability of the methods, their accuracy and computational effort is given and the effect of the liquid motion on the vessel motion is discussed.

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Section: Effect Of Liquid Cargomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Determination of Non-Linear Roll Damping of an FPSO Pure Roll Coupled with Liquid Sloshing in Two-Row Tanks

Igbadumhe

Sallam

Fürth

et al. 2020

JMSE

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“…In order to facilitate storage and long-distance transportation like petroleum, natural gas is usually liquefied to form liquefied natural gas (LNG) at atmospheric pressure at −162 • C after removing water, carbon dioxide and heavy hydrocarbons using adsorption and separation. Its volume is 1/600 of the gaseous state; its density is 600 times that of the standard state, and its weight is only 45% compared with the same volume of water [3,4]. LNG not only improves the efficiency of natural gas storage and transportation but also can recover natural gas resources in remote areas and make reasonable use to reduce resource waste.…”

Section: Introductionmentioning

confidence: 99%

Evolution Process of Liquefied Natural Gas from Stratification to Rollover in Tanks of Coastal Engineering with the Influence of Baffle Structure

Wang

Han

Liu

et al. 2021

JMSE

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During the storage process, liquefied natural gas (LNG) may undergo severe evaporation, stratification, and rollover in large storage tanks due to heat leakage, aging, or charging, causing major safety risks. Therefore, this article theoretically analyzes the causes and inducing factors of the LNG stratification and rollover phenomenon in the storage tank of coastal engineering. The computational fluid dynamics was used to establish a numerical model for the heat and mass transfer of LNG multicomponent materials in the imaginary layered interface of the storage tank, and the evolution process of LNG from spontaneous stratification to rollover was simulated. The accuracy of the mathematical model is verified by comparing numerical results with experimental data from open literature. The effects of the density difference between upper and lower layers, layering parameters, heat leakage parameters, and the baffles structure on the rollover process were studied. The effects of the interfacial surface variations are not included in this study. The results show that different baffle structures will form different boundary velocity fields, which will only affect the severity of the rollover, not the occurrence time. The larger the layering density difference, the earlier the rollover occurs. Under current conditions, the baffle structure that has the best suppression of rollover and the minimum boundary velocity is at 0.5 m above the stratified interface with the installation of the baffle at 5 degrees.

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“…A number of particularly severe incidents involving container ships and roll motions of up to 40 • intensified the research efforts in this particular field [3,4], but smaller roll angles will also have a significant influence on vessel usability and their detailed design [5,6]. A wide range of numerical models are suppose to predict the roll motion correctly [7][8][9][10] along with experimental investigations which provide case-specific validation data [11,12]. Zhou et al [13] and Zhou [14] showed good agreement between experimental investigations and a hybrid model, which connects a 3D-numerical calculation of the roll damping coefficient and in a second step the solution of the 3 Degree of Freedom (DoF) motion of the ship.…”

Section: Introductionmentioning

confidence: 99%

Roll Motion of a Water Filled Floating Cylinder—Additional Experimental Verification

Gabl

Davey

Ingram

2020

Water

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Understanding the behaviour of water filled bodies is important from an applied engineering perspective when understanding the sea-keeping performance of certain floating platforms and vessels. Even by assuming that the deformation is negligible small in relation to the motion of the structure, these fluid-structure-fluid interactions are challenging to model, both physically and numerically, and there is a notable lack of reference data sets and studies to support the validation of this work. Most of the existing information is highly specific to certain hulls forms, or is limited to small motions. A previous study addressed this by modelling a floating cylinder (giving a more generic case) with roll and pitch motions in excess of 20°. The presented experiment expands on that work to further investigate the previously observed switch between pitch and roll in the cylinder under wave action as induced by the sloshing of the internal water volume. An additional experimental investigation, focused on a single draft, was conducted to test open research questions from the previous study. Here we show that the roll response of the water filled cylinder is repeatable, independent of the tank position and wave amplitude, provided the observation time is long enough to capture the fully developed motion response of the floating object. The mooring system used comprised four soft lines connected on two points on the cylinder. This arrangement resulted in slightly different restoring forces in different wave directions. A relative change of the wave direction by 90° led to a larger wave frequency band in which the roll motion occurred. These cases were, again, also conducted with the solid ballast. Both sets of data provide an interesting validation case for future work on water ballast inside a floating object.

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Determination of Parameters Describing the Risk Areas of Ships Chaotic Rolling on the Example of LNG Carrier and OSV Vessel

Cited by 8 publications

References 25 publications

Experimental Determination of Non-Linear Roll Damping of an FPSO Pure Roll Coupled with Liquid Sloshing in Two-Row Tanks

Experimental Determination of Non-Linear Roll Damping of an FPSO Pure Roll Coupled with Liquid Sloshing in Two-Row Tanks

Evolution Process of Liquefied Natural Gas from Stratification to Rollover in Tanks of Coastal Engineering with the Influence of Baffle Structure

Roll Motion of a Water Filled Floating Cylinder—Additional Experimental Verification

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