Research on Collision Mechanism for a Ship Colliding With a Spar Platform

2007 ◽  
Author(s):  
Zhiqiang Hu ◽  
Weicheng Cui ◽  
Longfei Xiao ◽  
Jianmin Yang
Keyword(s):  
Numerical Simulation ◽  
Structural Damage ◽  
Simulation Method ◽  
Hydrodynamic Characteristics ◽  
Spar Platform ◽  
Mooring Lines ◽  
Hull Design ◽  
Truss Spar ◽  
Internal Mechanism ◽  
Double Hull

The collision mechanisms of spar platform haven’t caused so much attention as that of ships in the past, for the short of this kind of collision accidents reported. But this does not mean the impossibility of the collision accident in the future. The research on external mechanism and internal mechanism for a ship colliding with a spar platform is introduced in this paper. A model test is designed to study the external mechanism. The collision scenario is described as a ship colliding with a spar platform moored in 1500 meters water depth. The specifics of the spar’s motions and the tension forces of the mooring lines are gathered, to find the hydrodynamic characteristics in the collision scenario. It is found that the maximal displacements and the maximal pitch angles of the spar platform, and the maximal tension forces of mooring lines are all linearly proportional to the initial velocity of the striking ship basically. Mooring lines play elastic roles in the collision course. The internal mechanism of the ship colliding with the spar platform is achieved by numerical simulation method and the software used is MSC.DYTRAN. A Truss-Spar is taken as the object and a double hull structural design is adopted in the part of hard tank near water surface. The curves of collision characters and the structural damage are obtained. The crashworthiness of the double hull design is verified, through the numerical simulation results.

Collision Character Research for Semi-Submersible Through Model Test, Simplified Analytical and Numerical Simulation Method

2010 ◽  
Author(s):  
Zhiqiang Hu ◽  
Zhenhui Liu ◽  
Jo̸rgen Amdahl
Keyword(s):  
Numerical Simulation ◽  
Model Test ◽  
Simulation Method ◽  
Tension Force ◽  
Test Results ◽  
Buffer Effect ◽  
Mooring Lines ◽  
Column Structure ◽  
Collision Force ◽  
Energy Absorbing

The characters of the collision scenario when a semi-submersible is struck by a containership are studied in this paper, through the model test, simplified analytical method and numerical simulation. The model test is conducted in the Deepwater Offshore Basin in Shanghai Jiao Tong University. Two special devices are designed to fulfill the model test. One is Ship Launching Device, simplified as SLD, who can launch the striking ship with controllable velocity and in any horizontal direction. The other is Energy Absorbing Device, simplified as EAD, who can simulate the buffer effect of the column structure and collect the collision force as well. A numerical simulation is completed to get the approximate stiffness of the column structure, which is used to adjust the property of EAD. The motions of semi-submersible are obtained, and the collision force and the tension forces of mooring lines are also got. Collision scenario characters for semi-motion and tension force are summarized by the analysis of the model test results. The second collision phenomenon is observed. The collision force dominates the collision moment and the tension force of the mooring lines lags behind. A NTNU in-house program developed by analytical simplified method is also verified by the model test result. The comparison proves the feasibility of the program.

Three-Dimensional Numerical Simulation of the Flow around Two Side-by-Side Cylinders of Different Diameters

2014 ◽  
Vol 721 ◽  
pp. 199-202
Author(s):  
Zhen Xiao Bi ◽  
Zhi Han Zhu
Keyword(s):  
Numerical Simulation ◽  
Flow Direction ◽  
Three Dimensional ◽  
Cross Flow ◽  
Simulation Method ◽  
Scale Model ◽  
Hydrodynamic Characteristics ◽  
Eddy Simulation ◽  
Drag And Lift ◽  
Different Diameters

This paper presents the calculation of hydrodynamic characteristics of two side-by-side cylinders of different diameters in three dimensional incompressible uniform cross flow by using Large-eddy simulation method based on dynamical Smagorinsky-Lilly sub-grid scale model. Solution of the three dimensional N-S equations were obtained by the finite volume method. The numerical simulation focused on investigating the characteristic of the pressure distribution (drag and lift force), vorticity field and turbulence Re=. Results shows that, the asymmetry of the time –averaged velocity distribution in the flow direction behind the two cylinders is very obvious; the frequency of eddy shedding of the small cylinder is about twice of the large one. The turbulence of cylinders is more obvious.

Experimental Study on Wet Tow and Upending of a Truss Spar

2011 ◽  
Author(s):  
Lin Liu ◽  
Longfei Xiao ◽  
Zhiqiang Hu ◽  
Lijun Yang
Keyword(s):  
Experimental Study ◽  
Oil And Gas ◽  
Research Work ◽  
Hydrodynamic Characteristics ◽  
Test Results ◽  
Ocean Engineering ◽  
Spar Platform ◽  
Key Points ◽  
Truss Spar ◽  
Global Moment

In recent years, with the development of the deepwater oil and gas exploitation, the Spar platform has received more and more attention. A lot of research work has been done on the Spar platform, but experimental study on the process of wet tow and upending of Truss Spar is seldom conducted. Recently, a wet tow and upending model test of a Truss Spar was carried out in the State Key Laboratory of Ocean Engineering in Shanghai Jiao Tong University. The hydrodynamic characteristics and the global loads on the key points of the Truss Spar during the period of wet tow and upending are focused on. In the wet tow tests, the tow resistance, 6DOF motions, global loads and the relative wave elevations are measured and analyzed. During the upending simulation, the measuring parameters consist of the motions and the global moment at the connection points between the hard tank and the truss. The test program and test results are presented and discussed in this paper offering the value references for the wet tow and upending operation in reality of the Truss Spar.

scholarly journals Simulation of vertical tidal turbine based on OpenFOAM and influence of inlet turbulence

2019 ◽  
Vol 272 ◽  
pp. 01017
Author(s):  
Liu Yun-ya ◽  
Yu-chen Yang ◽  
Ya-wen Yang
Keyword(s):  
Numerical Simulation ◽  
Turbulence Model ◽  
Cfd Simulation ◽  
Vertical Axis ◽  
Simulation Method ◽  
Hydrodynamic Characteristics ◽  
Numerical Simulation Method ◽  
Tidal Turbine ◽  
Cfd Method ◽  
Control Equation

This paper first introduces the basic theory of CFD method, including basic control equations, finite volume method, control equation solving algorithm and turbulence model selection. Second, based on OpenFOAM, an open-source fluid mechanics software, a numerical simulation method of vertical axis tidal turbine was proposed by using k-ω SST turbulence model and PIMPLE algorithm. The hydrodynamic characteristics of the vertical axis turbine were studied, and the calculation results were compared with experiments. The higher consistency proves the feasibility of the numerical simulation method proposed in this paper. Finally, the influence of inlet turbulence on numerical simulation was explored, and a set of effective CFD simulation strategies was concluded, which provided a valuable reference for future CFD simulation and research on vertical axis tidal turbines.

scholarly journals A SLACK MOORING FOR A LARGE SHIP UNDER BEAM SEAS IN PORT

2018 ◽  
pp. 57
Author(s):  
Shigeki Sakakibara ◽  
Shunji Sunahara ◽  
Kaku Ito
Keyword(s):  
Numerical Simulation ◽  
Simulation Method ◽  
Mooring Line ◽  
Ship Motions ◽  
Physical Model Test ◽  
Mooring Lines ◽  
Beam Seas ◽  
Large Ship ◽  
Small Ship ◽  
Slack Mooring

As an empirical and traditional ship mooring method, a pretension mooring (a hard mooring) or slack mooring (without pretension in mooring line) is performed for large ship or small ship, respectively. However, the slack mooring is applied to a large ship under beam seas in port to avoid large roll and sway motions, and excessive loads in mooring lines and fenders. In this study, the mechanism and validity of the slack mooring for large ship is investigated by a physical model test and a numerical simulation method of the moored ship motions and mooring loads under beam seas.

A Fundamental Study on the Damage of Wash Up to the Quay of the Moored Vessel in Tsunamis Using the MPS Method Considered the Fender Influences

2018 ◽  
Author(s):  
Mitsuhiro Masuda ◽  
Kiyokazu Minami ◽  
Koichi Masuda
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Simulation Method ◽  
Implicit Method ◽  
Spring Model ◽  
Mooring Lines ◽  
Fundamental Study ◽  
Protection Measures ◽  
Mps Method ◽  
Moving Particle

In the case of vessels are moored at the quay, the drift and the wash up to the quay due to the broke of mooring lines is occurred by the tsunamis. In the previous study, the authors are examined to the applicability of the proposed tsunami protection measures as the install more mooring lines (IMML) and the floating tsunami protection wharf (FTPW). However, the Fender influences were not considered in previous authors studies. In this study, the fender influences are considered on the numerical simulation. The three-dimensional MPS (Moving Particle Semi-implicit) method is used as numerical simulation method. The linear compressing spring model is used as the fender model. The fender influences were investigated against the influences of tsunami protection measures using IMML and the damage status of vessel.

scholarly journals Hydrodynamic Characteristics of Different Undulatory Underwater Swimming Positions Based on Multi-Body Motion Numerical Simulation Method

2021 ◽  
Vol 18 (22) ◽  
pp. 12263
Author(s):  
Jin Yang ◽  
Tianzeng Li ◽  
Zhiya Chen ◽  
Chuan Zuo ◽  
Xiaodong Li
Keyword(s):  
Numerical Simulation ◽  
Water Depth ◽  
Water Surface ◽  
Swimming Performance ◽  
Simulation Method ◽  
Lateral Position ◽  
Body Motion ◽  
Hydrodynamic Characteristics ◽  
Joint Center ◽  
Multi Body

The study of hydrodynamic characteristics of swimming is the main way to optimize the swimming movement. The relationship between position, water depth, and swimming performance of undulatory underwater swimming are one of the main concerns of scholars. Therefore, the aim of this study is to analyze the swimming performance of three different undulatory underwater swimming positions under various swimming depths using a numerical simulation method based on multi-body motion. The simulation was conducted using 3D incompressible Navier–Stokes equations using the RNG k-ε turbulence closure equations, and in combination with the VOF method thus that we could include the water surface in our calculations. Different swimming depths based on the distance from the shoulder joint center to the initial water surface were considered. The velocity of the shoulder joint center was captured with a swimming motion monitoring system (KiSwim) and compared with the calculated results. The study found that there was a significant difference in the hydrodynamic characteristics of the three undulatory underwater swimming positions (i.e., the dorsal, lateral, and frontal positions) when swimming near the water surface, and the difference decreased as the swimming depth increased. There was a negative correlation (R(dorsal)= −0.928, R(frontal)= −0.937, R(lateral)= −0.930) between the swimming velocities of the three undulatory underwater swimming positions and the water depth (water depth= 0.2–0.7 m) and that the lateral position had the greatest average velocity. Therefore, it is recommended that swimmers travel at least 0.5 m below the water surface in any undulatory underwater swimming position in order to avoid excessive drag forces. As the swimmer approaches the water surface, the lateral position is worth considering, which has better velocity and hydrodynamic advantage than the other two undulatory underwater swimming positions.

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