CFD simulation of the vertical motion characteristics of the moonpool fluid for the truss spar

2014 ◽  
Vol 13 (1) ◽  
pp. 92-98 ◽  
Author(s):  
Bin Wang ◽  
Liqin Liu ◽  
Yougang Tang
Keyword(s):  
Cfd Simulation ◽  
Vertical Motion ◽  
Truss Spar ◽  
Motion Characteristics

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

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.

Motion Characteristics of Composite-Type Sea Cage under Pure Wave

2012 ◽  
Vol 490-495 ◽  
pp. 3405-3409
Author(s):  
Chun Liu Li ◽  
Yun Peng Zhao
Keyword(s):  
Experimental Data ◽  
Wave Height ◽  
Vertical Motion ◽  
Data Acquisition System ◽  
Horizontal Motion ◽  
Wave Condition ◽  
Composite Type ◽  
Motion Range ◽  
Motion Characteristics ◽  
Sea Cage

To study motion range changes with wave condition and motion relationship between cages, physical model experiments were carried out. The authors designed 2 models of composite-type sea cages. Experimental data obtained by the CCD data acquisition system. The experiment results showed that 1.in the same period, horizontal motion range,vertical motion range and inclination changes of float collar increase with wave height; 2.In the same wave height, horizontal motion range of the float collar increases with period; 3.The laws between vertical motion and period are not obvious 4.The laws between inclination changes and period are not obvious 5.Motion range of the first cage along the direction of waves is less than other cages.

scholarly journals A Study in Aerodynamic Optimization of UAV Helicopter Rotor- Blades Planform in Vertical Motion

AVIA ◽  
2021 ◽  
Vol 2 (1) ◽  
Author(s):  
M F Afthon ◽  
M A Moelyadi
Keyword(s):  
Cfd Simulation ◽  
Twist Angle ◽  
Vertical Motion ◽  
Vertical Movement ◽  
Rotor Blades ◽  
Aerodynamic Optimization ◽  
Blade Element Momentum Theory ◽  
Momentum Theory ◽  
Design Variables ◽  
Blade Element

According to the objectivity of UAV helicopter, endurance is a valuable performance. To increase the endurance, we need to decrease the helicopter required power. Within the research scope in vertical movement only, 5 parameters of blades planform design were considered as design variables. They are root chord of the blades, taper location, taper ratio, pitch angle, and tip twist angle. Optimization was done using own developed genetic algorithm codes with built-in blade element momentum theory (BEMT) as a performance calculator. It was chosen due to its ability to estimate rotor performance quickly. Several CFD simulation were done to reduce the error of blade element momentum theory calculation. Using constant adjustment methods, BEMT can predict thrust and power with a difference with respect to CFD of 3.8% and 8.2% respectively. The optimization result gives the optimum blades design with improving almost 11% in efficiency which came out from 9.4% reduction in power required which is good for helicopter performance.

Turbulence Measurements from Compliant Moorings. Part I: Motion Characterization

2017 ◽  
Vol 34 (6) ◽  
pp. 1235-1247 ◽  
Author(s):  
Samuel Harding ◽  
Levi Kilcher ◽  
Jim Thomson
Keyword(s):  
Vertical Direction ◽  
Vertical Motion ◽  
Inertial Subrange ◽  
Motion Sensors ◽  
Similar Frequency ◽  
Dynamic Motion ◽  
Flow Speeds ◽  
Motion Characterization ◽  
Motion Characteristics ◽  
Vessel Motion

AbstractHigh-fidelity measurements of turbulence in the ocean have long been challenging to collect, in particular in the middle of the water column. In response, a measurement technique has been developed to deploy an acoustic Doppler velocimeter (ADV) to midwater locations on a compliant mooring. A variety of instrumentation platforms have been deployed as part of this work with a range of dynamic motion characteristics. The platforms discussed herein include the streamlined StableMoor buoy (SMB), the Tidal Turbulence Mooring (TTM) system based on a conventional 0.9-m spherical buoy, and a 100-lb sounding weight suspended from the stern of a research vessel. The ADV head motion is computed from inertial motion sensors integrated into an ADV, and the spectra of these signals are investigated to quantify the motion of each platform. The SMB with a single ADV head mounted on the nose provided the most stable platform for the measurement of tidal turbulence in the inertial subrange for flow speeds exceeding 1.0 m s−1. The modification of the SMB with a transverse wing configuration for multiple ADVs showed a similar frequency response to the nose configuration in the horizontal plane but with large contamination in the vertical direction as a result of platform roll. While the ADV motion on the TTM was significant in the horizontal directions, the vertical motion of this configuration was the most stable of all configurations tested. The sounding weight measurements showed the greatest motion at the ADV head but are likely to be influenced by both prop-wash and vessel motion.

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

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.

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

2019 ◽  
Vol 2 (1) ◽  
pp. 28-33
Author(s):  
Ahmad Fitriadhy ◽  
Nur Adlina Aldin ◽  
Nurul Aqilah Mansor ◽  
Nur Aqilah Hanis Zalizan
Keyword(s):  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
Vertical Motion ◽  
Subsequent Increase ◽  
Pitch Motion ◽  
Insignificant Effect ◽  
Motion Characteristics ◽  
Heave Motion ◽  
Real Challenge ◽  
Naval Architect

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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