Offshore skids play a vital role in transportation of heavy pumps, engines, and blender units used during fracturing treatments at the well-site. For universal acceptance and usage of these skids worldwide, the offshore design should meet various applicable codes and regulations, such as Bureau Veritas, Lloyds, ABS, or Det Norske Veritas (DNV) design standards. This paper presents a review of the design, development, and implementation of an offshore skid per DNV regulations. A finite element approach of design was adopted to meet DNV requirements. Design implementation efforts, such as manufacturing, inspection, and prototype testing under different loading and lifting conditions are discussed. The output should help obtain DNV certification and guide global field operators during operation.
Sediment type of muddy intertidal flats was an important surface parameter and understanding of its distribution is capable of benefiting environmental protection as well as engineering management. Remote sensing has been widely used for mapping intertidal surfaces. However, the spectral signal of sediment is easily concealed by water. In order to weaken its impact, a linear spectral mixture model was employed to retrieve moisture content. Then, moisture was introduced into a regression equation to map sediment types. It is shown that this method has a good potential to map sediment types.
In this study, the full coupled effect between a lifted object and vessel motions is considered in both time and frequency domains for a typical construction vessel, Lewek Constellation (LCO). Two numerical models with and without effect of the lifted weight are simulated using the Ultramarine-MOSES software, and the numerical results from these models are compared to evaluate the dynamic effect of the lifted object on the vessel motions. Parametric studies are also investigated, considering different headings, significant wave heights, lifted weights and lifting positions. Dynamic amplification factors (DAF) obtained from sling forces of the rigging system are compared with the recommended values in the DNV practice code. This study gives a better understanding of the coupled lifted object – vessel motion system and may be useful for marginal lifting cases.
Jin, Jiyuan (Korea Research Institute of Ships and Ocean Engineering) | Hong, Keyyong (Korea Research Institute of Ships and Ocean Engineering) | Hyun, Beom-soo (Korea Maritime and Ocean University) | Lee, Geonggi (Korea Maritime and Ocean University) | Liu, Zhen (Ocean University of China)
Impulse turbine is widely used device as an energy converter in OWC type wave plant especially in Korea because of the wide operating range. Because the driven torque of blade is extracted form wave energy which is not an infinity force like fossil energy source, study on the unsteady characteristics of turbine such as self-starting performance are important to predict the performance of pilot plant in real sea conditions. The transient calculation method for performance prediction of OWC impulse turbine is proposed in the present paper using commercial CFD code Fluent, which is supposed to provide more valuable unsteady information during self-starting and rotating of the turbine. The rotation of turbine is derived from the angular acceleration, which are obtained from torques integration on rotor blades. The frictions and electricity generator loading are regarded as the counteractive force contributing to the above torque calculations. The experimental study is carried out using wave simulator test rig which can simulate a sinusoidal flow in test section. The RPM of turbine, torque of blade and pressure different induced by turbine are measured to study unsteady characteristics under variable flow and resistance loading conditions.
The paper presents the description of an experimental method for strength criteria of concrete. The concrete is considered as a threecomponent structure that allows one to use the integrated characteristics of fracture toughness for concrete in terms of specific energy. This energy is sufficient to form the new surfaces resulting from fracture through an outlay of energy for mechanical rupture of the internal ties in concrete. Concrete samples with two cracks were studied in two directions.
Maneuverability is one of the most important overall performances of underwater vehicle. Good maneuverability is very important for ensuring the safety of underwater vehicle’s navigation and improving the underwater vehicle’s work effectiveness. The conventional approach of evaluating maneuverability is to calculate the performance indexes respectively from the vertical motions and the horizontal motions. The only typical space motion of underwater vehicle, spatial helical motion, can’t reflect the maneuverability comprehensively. This paper aims to design an innovative space motion for underwater vehicle.
The paper will start with analyzing the coupling effect of vertical motions and horizontal motions. Based on the existing typical six degree of freedom motion of aircraft, a space motion that can describe the character of general space motion will be devised by simulation method, at the same time, ensuring the safety of the navigation. This research provides a new space motion for the evaluation of maneuverability and maneuvering test, so as to extract the new space motion’s indexes that can clearly describe the maneuverability of the underwater vehicle. It complements the existing evaluation system of maneuverability for underwater vehicle.
It was demonstrated, in a study presented at ISOPE 2013 (Cao, et al 2013), that treating the liquid in a fully-filled tank as a rigid body when calculating the moment on the tank by the liquid can result in significant error. CFD simulations were performed to study the effects of the liquid movement for 2-D tanks with square and circular cross sections. Based on the results of the study, a simple method was proposed for including the effect of the liquid movement in a fully-filled tank in the calculation of the motions of the ship (or vessel) in regular wave. This paper extends the previous study to tanks with rectangular cross sections. The present study confirms the findings in the previous study for the tanks with square or circular cross sections. In addition, the effect of the length-height ratio of the rectangular cross section is investigated. A preliminary investigation indicates that it is possible to extend the simple method to the prediction of the ship motions in random seas using the frequency-domain approach.
Cho, Tae-Min (Samsung Heavy Industires Co., Ltd.) | Park, Joo-Shin (Samsung Heavy Industires Co., Ltd.) | Ha, Yeong-Su (Samsung Heavy Industires Co., Ltd.) | Kim, Bong-Jae (Samsung Heavy Industires Co., Ltd.) | Jang, Ki-Bok (Samsung Heavy Industires Co., Ltd.)
In this study, global in-place analysis of WTIV (Wind Turbine Installation Vessel) leg for Korean west-south offshore wind zone is performed through finite element analysis. Firstly, environmental conditions and seabed characteristics of Korea west-south offshore wind zone is collected and investigated through both direct measurements and literature surveys. Based on these data, design specifications are established and the overall basic design is performed. Dynamic characteristics of the WTIV for Korean west-south offshore wind zone are considered in the global in-place analysis of leg and the stability against overturning moment is also analyzed. The structural integrity of the WTIV leg is verified through the code checks and the adequate safety margin is observed. The results of this study can be expected as practical and useful data for the design of the WTIV for Korean west-south offshore wind zone.
Abdussamie, Nagi (NCMEH, Australian Maritime College (AMC), University of Tasmania (UTAS)) | Amin, Walid (NCMEH, Australian Maritime College (AMC), University of Tasmania (UTAS)) | Ojeda, Roberto (NCMEH, Australian Maritime College (AMC), University of Tasmania (UTAS)) | Thomas, Giles (NCMEH, Australian Maritime College (AMC), University of Tasmania (UTAS)) | Tasmania, Launceston (_) | Drobyshevski, Yuriy (INTECSEA Pty Ltd.)
The risk assessment of wave-in-deck loading on fixed platform decks requires accurate prediction of both global and local loading. In this paper, the vertical loading generated on the bottom plate of a rigidly mounted box-shaped structure due to unidirectional regular waves is computed by means of two approaches. The first is a component-based approach based on Kaplan’s method and the second is a computational fluid dynamics (CFD) approach based on the volume of fluid (VOF) method implemented in the commercial CFD code FLUENT. Different parameters including wave steepness and air gap are tested. The obtained results are validated against tank experiments. The study revealed that when the wave-in-deck events are measured globally and locally the load magnitude, its duration as well as its distribution is better evaluated and the uncertainty involved with these impulsive loads can be reduced. It was found that in many cases Kaplan’s method underestimates the magnitude of the force in the upward direction. CFD force predictions were found to be in better agreement with the measured forces.
Shibue, Tadashi (Kinki University) | Kajiya, Takeshi (Kinki University) | Shiba, Ryohei (Kinki University) | Hayami, Takashi (Kinki University) | Sawai, Toru (Kinki University) | Ohmasa, Mitsushi (Kinki University) | Hirokawa, Noriyasu (Kinki University) | Kato, Kazuyuki (Kinki University)
Fender has been used for the protection of ship hull from impact forces caused at the berthing to a quay, by its shock absorbing effects. It is also useful to avoid damages to the passengers and crew, and to protect the quay. In this study, the effects of cross sectional shape of a fender on its buffering capability are examined based on the drop weight tests and the numerical simulation with FEM. This is useful for the development of a fender with high performance buffering capability.