Experimental investigation on dynamic responses of FLNG connection system during side-by-side offloading operation

Zhao, Dongya; Hu, Zhiqiang; Chen, Gang

doi:10.1016/j.oceaneng.2017.03.034

Cited by 27 publications

(7 citation statements)

References 19 publications

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“…Bigger tanks are more susceptible to damage from pressure peaks caused by the internal sloshing [30,31]. Xu et al [32] and Zhao et al [33] investigated the side-by-side operation of two vessels through experiments at a scale of 1:60. A numerical simulation of such a combination is presented by Zhao et al [34].…”

Section: Introductionmentioning

confidence: 99%

Comparison of a Floating Cylinder with Solid and Water Ballast

Gabl

Davey

Nixon

et al. 2019

Water

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Modelling and understanding the motion of water filled floating objects is important for a wide range of applications including the behaviour of ships and floating platforms. Previous studies either investigated only small movements or applied a very specific (ship) geometry. The presented experiments are conducted using the simplified geometry of an open topped hollow cylinder ballasted to different displacements. Regular waves are used to excite the floating structure, which exhibits rotation angles of over 20 degrees and a heave motion double that of the wave amplitude. Four different drafts are investigated, each with two different ballast options: with (water) and without (solid) a free surface. The comparison shows a small difference in the body’s three translational motions as well as the rotation around the normal axis to the water surface. Significant differences are observed in the rotation about the wave direction comparable to parametric rolling as seen in ships. The three bigger drafts with free surface switch the dominant global rotation direction from pitch to roll, which can clearly be attributed to the sloshing of the internal water. The presented study provides a new dataset and comparison of varying ballast types on device motions, which may be used for future validation experiments.

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Section: Introductionmentioning

confidence: 99%

Comparison of a Floating Cylinder with Solid and Water Ballast

Gabl

Davey

Nixon

et al. 2019

Water

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“…Ships containing liquefied natural gas are another comparable application. However, in many cases, these experimental investigations incorporate very complex geometry which is case specific and/or superimposed with complex research questions, e.g., the interaction between two ships [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Experimental Data of a Floating Cylinder in a Wave Tank: Comparison Solid and Water Ballast

Gabl

Davey

Nixon

et al. 2019

Data

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The experimental set-up allows for the comparison of two different ballast options of a floating cylinder in a wave tank. Four different internal water drafts are tested as well as an equivalent solid ballast option. The model is excited by regular waves, which are characterised with five wave gauges in front of the floating cylinder and two behind. Additionally, the time series of the six-degree freedom response of the floating structure is made available. Regular waves with an initial amplitude of 0.05 m and frequencies over the range 0.3 to 1.1 Hz are investigated. This results in a wide range of different responses of the floating structure as well as very big rotations of up to 20 degrees. This dataset allows for identification of the influence caused by the sloshing of the interior water volume and can be used to validate numerical models of fluid–structure–fluid interaction.

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“…The LNG produced is then taken off the FLNG by a shuttle LNG Carrier connected in a side-by-side configuration. Before going into the offloading operation, the LNG Carrier needs to arrive on-site near the FLNG, manoeuvre and position itself alongside the FLNG, either with the assistance of tugs or through a dynamic positioning system [1][2][3][4]. For positioning of the LNG Carrier next to the FLNG under the time-varying environmental disturbance, this can be formulated as a control problem with operation limits and the side shell of FLNG can be as position constraints, which the system needs to meet collisions avoidance and the smooth and safe operations.…”

Section: Introductionmentioning

confidence: 99%

Dynamic control for LNG carrier with output constraints

Liang

Zhang

et al. 2022

IET Control Theory & Appl

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This paper addresses constrained robust control for dynamic positioning of the Liquefied Natural Gas (LNG) Carrier in side-by-side offloading operations subject to input time delay. During the LNG offloading operation, the relative motions of the multibody system are connected by the LNG offloading arm. To ensure the operation safety, robust control with asymmetric Barrier Lyapunov Function is proposed considering predefined output constraints under the unknown dynamics and external disturbances. In offshore engineering, due to the mechanical effects, the thrusters of the LNG carrier in the presence of time-delay should be investigated to guide the design practice. The predictor-based method is employed to deal with the time delay induced by the control inputs. It is proven that the proposed scheme can guarantee semi-global uniform ultimate boundedness. The performance and feasibility of the proposed control are further verified by simulation studies.

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Experimental investigation on dynamic responses of FLNG connection system during side-by-side offloading operation

Cited by 27 publications

References 19 publications

Comparison of a Floating Cylinder with Solid and Water Ballast

Comparison of a Floating Cylinder with Solid and Water Ballast

Experimental Data of a Floating Cylinder in a Wave Tank: Comparison Solid and Water Ballast

Dynamic control for LNG carrier with output constraints

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