Heave and Pitch Motion Performances of a Ship Towing System Incorporated with Symmetrical Bridle Towline Model

An investigation on vertical motion characteristics of a ship towing system incorporated with symmetrical bridle towline configuration set a real challenge for the naval architect engineer. This paper presents a Computational Fluid Dynamic (CFD) approach to analyse heave and pitch motion performances in waves. Several towing parameters such as various towline length and towing’s velocity have been taken into account. Here, 1B (barge) is employed in the simulation; and designated as a towed ship. The results revealed that the subsequent increase of the towline lengths has been basically proportional with the increase of her heave motion; while inversely decrease in pitch motions. In addition, the effect of the extending towline length = 1.0 to 3.0 resulted in insignificant effect to the towline tension. However, the increase of the towing’s velocity from 0.509 m/s to 0.728 m/s has led to significantly increase her heave motion and the towline tension by 40.46% and 24%, respectively; meanwhile, the pitch motion barge has sufficiently decreased by 35.94%. This simulation has been beneficial for the towing operator to ensure a higher level of the safety navigation of ship towing system.

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CFD ANALYSIS ON VERTICAL MOTION OF A FULL-SCALE FLOATING JETTY

Journal of Sustainability Science and Management ◽

10.46754/jssm.2020.08.009 ◽

2020 ◽

Vol 15 (6) ◽

pp. 100-110

Author(s):

AHMAD FITRIADHY ◽

◽

AMIRA ADAM

Keyword(s):

Cfd Simulation ◽

Vertical Motion ◽

Cfd Analysis ◽

Subsequent Increase ◽

Pitch Motion ◽

Motion Responses ◽

Harsh Environmental Condition ◽

Computational Fluid Dynamics Cfd ◽

Response Amplitude Operators ◽

Motion Characteristics

A floating jetty often experiences several vertical motions i.e., heave and pitch motion responses due to harsh environmental condition. This inherently makes discomfort to everyone during berthing on a floating; and even it potentially leads to loss of life due to falling down into the sea. A preliminary analysis using Computational Fluid Dynamics (CFD) simulation is necessary to be conducted to ensure user’s safety. The CFD analysis focused on the interaction between wave motions and the floating jetty and its effects on the vertical motions. The vertical motions of floating jetty were quantified by the Response Amplitude Operators (RAO). Several effects due to variation of wavelength (λ/L) have been studied. The CFD results revealed that the lower wavelength (λ/L<2.25) resulted in the increase of the heave and pitch motion amplitudes proportionally. However, the subsequent increase of wavelength (2.25>λ/L) has given results to less heave and pitch motion amplitudes. In general, it is shown that the vertical motion characteristics of the floating jetty predominantly depend on wave properties.

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Heave and Pitch Motions of a Towed Ship in Waves Incorporated with an Asymmetrical Bridle Towline Model

EPI International Journal of Engineering ◽

10.25042/epi-ije.022019.07 ◽

2019 ◽

Vol 2 (1) ◽

pp. 34-40

Author(s):

Ahmad Fitriadhy ◽

Nurul Aqilah Mansor ◽

Nur Adlina Aldin

Keyword(s):

Cfd Simulation ◽

Fluid Dynamic ◽

Wave Condition ◽

Pitch Motion ◽

Calm Water ◽

Motion Characteristic ◽

Motion Characteristics ◽

Sufficient Reduction ◽

Sway Motion ◽

Motion Amplitude

Investigation of a ship towing system performance in waves incorporated with an asymmetrical towline configuration is necessarily to be studied to ensure a towing safety of navigation. To achieve the objective, this paper presents the ship towing motion performance in waves using Computational Fluid Dynamic (CFD) approach. Here, the heave and pitch motions of the towed ship so-called barge has been analysed, where several effects of the towing angle and towing speeds have been taken into account. In the calm water condition, the results revealed that the increase of tow angle was proportional with the sufficient reduction of the sway amplitude motion and inversely proportional to her yaw motion. The increase of the asymmetrical tow angle, however, has led to increase her sway motion amplitude in wave condition and conversely reduced the tow speed increased. In addition to the pitch motion characteristic, it subsequently increased by 12.1% as the tow angle raised from 25° to 35°; meanwhile the pitch motion of barge has by 10.2% as the tow speed increased from 0.655 m/s to 0.728 m/s. This CFD simulation is very useful as the preliminary prediction on the heave and pitch motion characteristics ensure a safety navigation of a towed ship in waves.

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A State of Art FPSO With Dry Tree System

Volume 1: Offshore Technology ◽

10.1115/omae2009-80229 ◽

2009 ◽

Author(s):

Chunqun Ji

Keyword(s):

Environmental Conditions ◽

Vertical Direction ◽

Vertical Motion ◽

Wide Range ◽

Floating System ◽

Motion Characteristics ◽

Heave Motion ◽

State Of Art

This paper provides a state of art dry tree floating system by using a moored column-buoy connected to a ship shaped vessel. The Buoy Moored Floating Production Storage and Offloading system (BMFPSO) uses a column-buoy instead of the turret in a conventional FPSO design. Similar to the turret, the column-buoy allows the vessel to weather vane about the column-buoy. In addition, the vessel can move in vertical direction relative to the column-buoy. Thus vertical motion of the column-buoy is de-coupled from the FPSO hull motion. The buoy will have relatively small heave motion allowing the use of proven top tensioned riser technology. The motion characteristics of the system make it operable in a wide range of environmental conditions.

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