Ferreira, Cristiano Zacarias (Federal University of ABC) | Conte, Gerson Yuri Cagnani (Federal University of ABC) | Ribeiro, Thiago Morais Ceratti (Federal University of ABC) | Avila, Juan Pablo Julca (Federal University of ABC)
This work presents the conceptual design and reports the hydrodynamic parameters obtained by system identification of a Hybrid Remotely Operated Vehicle (HROV), the word hybrid is because the vehicle has mode two of operation: free-flying and crawler. The parameter identification is considered in a decoupled mode, equations for movements in yaw, heave and surge were identified. The HROV is being developed at Federal University of ABC in Brazil to measure ship hull thickness by using ultrasonic transducers. The parameter identification of the vehicle was performed using the embedded sensors and thrusters as alternative cost-effective and less time-consuming than using PMM’s (Planar Motion Mechanisms). The experimental tests were carried out using the automatic control system of the vehicle and conducted to minimize the water surface tank wall effects on the flow, the results found on this work permit the use, in future works, for advanced control purposes and for comparison with other techniques of parameter identification.
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.
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.
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.
Wastewater discharge into coastal areas, which is usually in the form of turbulent jets, may cause serious environmental problems in the coastal zone. In the near field, the discharged jet is not only driven by its initial momentum, but is also affected by the surrounding coastal dynamic forces, such as tidal currents and waves. In this study, a generic large eddy simulation (LES) model is developed to simulate the jet near-field behaviours in various coastal environments, including cross-flow currents, waves, coexisting waves and cross-flow currents. It is shown that all the modelling results are consistent well with the experimental data, indicating the model is a useful tool to predict the jet initial movements in various coastal environments.
Ku, Namkug (Dong-eui University) | Ha, Sol (Seoul National University) | Hwang, Ho-Jin (Korea Research Institute of Ships and Ocean Engineering) | Lee, Kyu-Yeul (Seoul National University) | Roh, Myoung-Il (Seoul National University)
This paper proposed a scenario manager capable of creating and editing shipbuilding production processes for multibody dynamics-based simulation. The proposed scenario manager was composed of three components: Actor, Scenario Executor, and Integrator. Actor represents a minimum unit of action in multibody dynamics kernel and it can be connected with specific component of dynamics kernel such as body, joint, wire, and so on. A shipbuilding production process can be made by combining these actors sequentially and in parallel. Including these combination of actors, Action List contains information for executing actors. Scenario Executor has this action list, and executes actors according to the execution order in the action list. Since the process of shipbuilding production is a kind of event-based sequence, all components of the scenario manager were configured using DEVS (discrete event system specification) formalism. To verify the effectiveness of the proposed scenario generator, it was applied to various shipbuilding production simulation such as lifting and erection of a block, heavy load lifting operation using multi-crane, and launching operation of an icebreaker using two floating cranes.
Ye, Xiaorong (Norwegian University of Science and Technology) | Gao, Zhen (Norwegian University of Science and Technology) | Moan, Torgeir (Norwegian University of Science and Technology) | Zhang, Liang (Harbin Engineering University)
Spar platform accommodating to intermediate and deep water is a reliable offshore structure that can support large floating offshore wind turbines (FOWT). In this paper, the hydrodynamic performance of FOWT is investigated by using experimental and numerical methods. The experiments are carried out for two models of 1:80 scales, one cylindrical spar and the other with heave plate at the bottom, respectively. In addition, at rated and extreme sea state, the wind force on the spar is modeled by a pulley-weight system attached to the spar top. The hydrodynamic force and motion response for both models are computed using combination of potential theory and Morison formulation. The viscous force on heave plate is approximated by choosing reasonable drag coefficient in the Morison formulation. The numerical and tests results are presented for the regular and irregular waves cases. Hydrodynamic prediction of the cylindrical spar is validated by the tests. But the difference of the cylindrical spar with heave plate exists between numerical prediction and the tests due to the behavior of the heave plate.
In this paper the partial differential equations of transverse vortex-induced vibration of a single pile considering pile and soil interaction are established, in which the pile is simplified as Euler-Bernoulli beam and can be divide into two segments of pile. The upper segment of pile is excited by fluid forces and the lower segment of pile interacts with the seabed which can be simplified as a viscoelastic medium. By means of the methods of stiffness transmission, the equations can be solved analytically on the basis of Laplace transformation. By virtue of MATLAB to solve the equation, the properties of vortex-induced vibration of marine pile are illustrated.
Liu, Baolin (Chinese Academy of Sciences) | Li, Jian (Chinese Academy of Sciences) | Peng, Yan (Chinese Academy of Sciences) | Zhao, Lingzhi (Chinese Academy of Sciences) | Li, Ran (Chinese Academy of Sciences) | Xia, Qi (Chinese Academy of Sciences) | Sha, Ciwen (Chinese Academy of Sciences)
The performance characteristics of a 2kw LMMHD generator with U47 as working liquid for wave energy conversion were investigated experimentally in this paper. The results show that in a simulated wave condition with a period of 2s and a stroke of 300mm, the LMMHD generator experiment device generates AC electricity and the output voltage, current and power change sinusoidally with time; the maximum output power of 1.1kW was measured with a load resistance of 45µΩ: and magnetic flux density of 0.9T. The experiment results of the open-circuit satisfy well with those from calculations.
Based on body nonlinear theory, the hydrodynamic problems of a three-dimensional body undergoing large amplitude motions are studied in the time domain. In the present method, the exact body boundary condition is satisfied on the instantaneous wetted surface while the free surface boundary condition is linearized. The initial-boundary value problem is formulated using a time-domain Green function. A “Time-frequency Transform Method” is proposed to calculate the convolution involving time-domain Green function. Numerical computations are first carried out for a submerged sphere undergoing forced motions. The results are compared with the published solutions, which validate the numerical model. Further computations are performed for a mooring JIP Spar in bichromatic waves. The body nonlinear effects on the results are discussed by comparison with linear time-domain solutions.