Application of Energy Saving Bow Shape in Actual Seas to JBC

2021 ◽  
Author(s):  
Akiko Sakurada ◽  
Masaru Tsujimoto ◽  
Saori Yokota
Keyword(s):  
Energy Saving ◽  
Side Wall ◽  
Video Camera ◽  
Wave Form ◽  
Bulk Carrier ◽  
Head Waves ◽  
Wave Heights ◽  
Added Resistance In Waves ◽  
Energy Efficiency Design Index ◽  
Actual Seas

Abstract Energy Efficiency Design Index (EEDI) entered Phase 2 in 2020. In this situation, ship performance in actual seas is more important than ever. As an energy saving bow shape in actual seas, the authors are developing a bow shape named “COVE (Concave shape optimized in waves)”. The aim of COVE is to improve performance in waves without deteriorating performance in a calm sea by transformation above the static swell up at the target speed. Since the bow shape is concave above the static swell up, COVE reduces waves reflected forward because the most concave line has a fine triangular shape instead of the blunt shape of the original. In this paper, COVE is applied to a Capesize bulk carrier, the JBC (Japan Bulk Carrier). The parameters of COVE are examined and the shape is optimized for the JBC. The effect of COVE is validated by tank tests in terms of wave lengths, wave angles, wave heights and ship speeds. The results clarified the fact that COVE reduces added resistance in waves by approximately 30 % in head waves compared with the original shape. Validity was verified by the radiating wave shape and the side wall wave form recorded by a video camera in the tests.

Numerical Research on FPSOs With Green Water Occurrence

2009 ◽  
Vol 53 (01) ◽  
pp. 7-18
Author(s):  
Renchuan Zhu ◽  
Guoping Miao ◽  
Zhaowei Lin
Keyword(s):  
Three Dimensional ◽  
Green Water ◽  
Floating Body ◽  
Incoming Wave ◽  
Model Case ◽  
Floating Structures ◽  
Design And Optimization ◽  
Head Waves ◽  
Wave Heights ◽  
The Impact

Green water loads on sailing ships or floating structures occur when an incoming wave significantly exceeds freeboard and water runs onto the deck. In this paper, numerical programs developed based on the platform of the commercial software Fluent were used to numerically model green water occurrence on floating structures exposed to waves. The phenomena of the fixed floating production, storage, and offloading unit (FPSO) model and oscillating vessels in head waves have been simulated and analyzed. For the oscillating floating body case, a combination idea is presented in which the motions of the FPSO are calculated by the potential theory in advance and computional fluid dynamics (CFD) tools are used to investigate the details of green water. A technique of dynamic mesh is introduced in a numerical wave tank to simulate the green water occurrence on the oscillating vessels in waves. Numerical results agree well with the corresponding experimental results regarding the wave heights on deck and green water impact loads; the two-dimensional fixed FPSO model case conducted by Greco (2001), and the three-dimensional oscillating vessel cases by Buchner (2002), respectively. The research presented here indicates that the present numerical scheme and method can be used to actually simulate the phenomenon of green water on deck, and to predict and analyze the impact forces on floating structures due to green water. This can be of great significance in further guiding ship design and optimization, especially in the strength design of ship bows.

Ship Operational and Safety Aspects of Ballast Water Exchange at Sea

1994 ◽  
Vol 31 (04) ◽  
pp. 315-326
Author(s):  
John B. Woodward ◽  
Michael G. Parsons ◽  
Armin W. Troesch
Keyword(s):  
Bending Moment ◽  
Bending Moments ◽  
University Of Michigan ◽  
Bulk Carrier ◽  
Rough Water ◽  
Design Values ◽  
Wave Heights ◽  
Ballast Tanks ◽  
The University ◽  
Wave Induced

A dry bulk carrier, a tanker, and a containership—taken as typical of ships trading to U.S. ports—are analyzed for possible hazards caused by emptying and refilling ballast tanks at sea. Using hydrostatic data furnished by the shipowners, hull bending moments and stabilities are investigated to find the tank-emptying operations that produce the greatest changes in those parameters. As should be expected, bending moment changes do not exceed allowable stillwater values. Changes in GM are insignificant. The worst hydrostatic cases serve as a guide to conditions that should be analyzed in rough water. The University of Michigan SHIPMO program shows that in waves of 10-ft significant height wave-induced bending moments and shears are far below the design values published by the American Bureau of Shipping. On the other hand, in waves of 20-ft significant height, the maximum wave heights that occur occasionally can cause moments or shears that exceed design values. For the 20-ft case, both linear and nonlinear versions of SHIPMO are used.

scholarly journals Исследования особенностей снижения продольной качки и дополнительного сопротивления судна с крыльевыми устройствами

2020 ◽  
Author(s):  
Z.M. Htet
Keyword(s):  
Energy Saving ◽  
Orbital Motion ◽  
Calculated Data ◽  
Ship Motions ◽  
Added Resistance ◽  
Regular Waves ◽  
Kinematic Parameters ◽  
Coupled Equations ◽  
Added Resistance In Waves ◽  
Oscillating Foil

В данной статье на основе предложенного расчета качки судна с энергосберегающими крыльевыми устройствами производится оценка мореходности и ходкости такого судна и возможности целенаправленного уменьшения амплитуд качки и снижения дополнительного сопротивления на волнении. Продольная качка судна заданного типа, обводов и размерений при наличии крыльевых элементов на заданном регулярном волнении рассчитывается с привлечением совместных уравнений вертикально-килевой качки с учетом демпфирования и инерции крыльевых устройств. При этом используется теория Теодорсена колеблющегося профиля и разложение нестационарных коэффициентов подъемной силы и момента по кинематическим параметрам при комбинировании вертикальных и угловых колебаний, и, в общем случае, в условиях воздействия орбитального движения жидкости. Для оценки дополнительного сопротивления используется теория Герритсмы и Бекельмана. В ходе расчетов демонстрируется влияние на дополнительное сопротивление удлинения и площади энергосберегающих крыльев, а также возможности снижения дополнительного сопротивления при совместном использовании носового и кормового крыльев по сравнению со случаем использования только одного (носового или кормового) крыла. Полученные расчетные данные позволяют получить представление о механизме влияния энергосберегающих крыльев на умерение амплитуд качки и снижение дополнительного сопротивления на волнении.In this article on the basis of the method for calculation of longitudinal motions of a ship with energy-saving wing devices proposed there is made an estimation of seaworthiness and seagoing capacity of such a ship and also of a possibility of directed decrease of ship motions amplitudes and added resistance in waves. The longitudinal motions of a ship of a given type, configuration and dimensions, in presence of wing elements, and in given regular waves is calculated with use of coupled equations of heave and pitch motions with account of damping and inertia of wing devices. Used therewith is Theodorsen theory of oscillating foil and expansion of lift and moment coefficients with respect to kinematic parameters for combined heave-and-pitch oscillations and, in general case, subject to action of orbital motion of fluid particles. To estimate added resistance the Beuklman-Gerritsma theory is used. Demonstrated in the course of calculations is the influence of aspect ratio and area of energy-saving wing upon the added resistance as well as upon its decrease when combining use of both bow and stern wings as compared to the case of using just one (bow or stern) wing. Obtained calculated data allow to understand the mechanism of the influence of energy-saving wings upon decrease of the amplitude of ship motions and the added resistance in waves.

scholarly journals Development of the New Energy Saving Device for the Reduction of Fuel of 176k Bulk Carrier

2015 ◽  
Vol 52 (6) ◽  
pp. 419-427 ◽  
Author(s):  
Hyun-Jin Song ◽  
Moon-Chan Kim ◽  
Won-Joon Lee ◽  
Kyoung-Wan Lee ◽  
Ji-Hee Kim
Keyword(s):  
Energy Saving ◽  
Bulk Carrier ◽  
New Energy

scholarly journals DESIGN OF A POWERFUL AND PORTABLE MULTIDIRECTIONAL WAVEMA

2017 ◽  
pp. 29
Author(s):  
Andrew Malcolm Cornett ◽  
Peter Laurich ◽  
Enrique Gardeta ◽  
Daniel Pelletier
Keyword(s):  
National Research Council ◽  
Side Wall ◽  
Wave Basin ◽  
Wave Generator ◽  
Wave Heights ◽  
Regenerative Power ◽  
Active Wave ◽  
Multidirectional Wave ◽  
And Control ◽  
New Machine

A new multidirectional wave generator with 72 independent paddles has been designed, fabricated and commissioned at the National Research Council labs in Ottawa, Canada. The wet-back piston-mode machine is installed in a new 50 m long by 30 m wide rectangular wave basin, where water depths can be varied over the range from 0 m up to 1.3 m. The new machine is believed to be unique in the world in that it combines the power and stroke required to generate multidirectional spectral wave conditions with significant wave heights exceeding 0.4 m together with the modularity and ease of portability required to move the machine quickly and safely to new positions. The new machine can also be sub-divided to form several shorter machines if desired. The new wave generator features lightweight, composite materials, energy efficient regenerative power supplies, state-of-the-art software and control systems, including capabilities for active wave absorption (reflection compensation), second-order wave generation for improved generation of nonlinear sub- and super-harmonics, side-wall reflection, and more. The design of this new directional wavemaker is described and several of the more innovative features are highlighted in this paper.

Detailed Study on the Behavior of Ships in Very Short Waves

2020 ◽  
Author(s):  
Saori Yokota ◽  
Mariko Kuroda ◽  
Ryohei Fukasawa ◽  
Hiroki Ohba ◽  
Masaru Tsujimoto
Keyword(s):  
Sensitivity Analysis ◽  
Fuel Consumption ◽  
Added Resistance ◽  
Regular Waves ◽  
Short Waves ◽  
Added Resistance In Waves ◽  
Tank Test ◽  
Ship Performance ◽  
Ship Operation ◽  
Actual Seas

Abstract Considering the sea conditions in which a large ship encountered in operation, the ship’s behavior in very short waves is important. However, the evaluation of the ship performance in very short waves was not enough validated by tank tests. Because it is difficult to generate waves with enough accuracy due to the performance of the wave generator. In this paper, it is shown that tank tests of added resistance in the regular waves including the very short waves are conducted in the Actual Sea Model Basin at National Maritime Research Institute, MPAT for DTC container ship and accurate results are obtained. The test results are compared with the benchmarks published by SHOPERA (Energy Efficient Safe SHip OPERAtion). In addition, three curves of the added resistance in the regular waves based on the results of the tank test are compared and the sensitivity analysis of energy efficiency is discussed. In the sensitivity analysis, the performance simulator for ships in actual seas (VESTA) is used, and a comparison is carried out for the fuel consumption calculated from the frequency response of each added resistance in waves. As a result, it is found that the tendency in added resistance in very short waves affects the fuel consumption and the decrease of ship speed.

An overset RaNS prediction and validation of full scale stern wake for 1,600TEU container ship and 63,000 DWT bulk carrier with an energy saving device

2020 ◽  
Vol 105 ◽  
pp. 102417
Author(s):  
Nobuaki Sakamoto ◽  
Hiroshi Kobayashi ◽  
Kunihide Ohashi ◽  
Yasutaka Kawanami ◽  
Björn Windén ◽  
...  
Keyword(s):  
Energy Saving ◽  
Full Scale ◽  
Container Ship ◽  
Bulk Carrier

Evaluation of hydromorphological conditions of Grand Popo Beach using two unique video cameras

2021 ◽  
pp. 1-36
Author(s):  
KoueKam K. Arnaud ◽  
Frédéric Bonou ◽  
Zacharie Sohou ◽  
Donatus B. Angnuureng ◽  
Rafael Almar
Keyword(s):  
Video Camera ◽  
Spatial And Temporal Patterns ◽  
Peak Period ◽  
Video Cameras ◽  
Significant Wave ◽  
Wave Heights ◽  
Wave Energy Flux ◽  
Significant Wave Heights ◽  
Erosion And Accretion ◽  
The Impact

Beaches are characterized by complex spatial and temporal patterns of erosion and accretion subjected to significant wave and tide influence. The objective of this study is to estimate the evolution of hydromorphodynamic conditions on the shoreline of Grand Popo Beach observed from two adjacent video camera setups. We have analyzed the impact of the variability of hydrodynamic parameters on the beach evolution and evaluated the variabilities of the hydrodynamic and morphologic parameters from the two cameras. Despite the nonhomogeneity within the cameras’ intrinsic properties, the various results obtained from the two systems indicate that wave conditions (peak period and significant height) from the cameras have the same variations, whereas the shoreline variations of camera A are not the same as those of camera B. It is generally during the summer that the Grand Popo Beach is exposed to an agitated environment with strong observed values of significant wave heights and wave energy flux, undoubtedly resulting in significant sediment transport along the beach leading a shoreline retreat. The results indicate that in 3.5 years the shoreline of Grand Popo Beach has retreated by 10 m.

scholarly journals On the Estimation of the Surface Elevation of Regular and Irregular Waves Using the Velocity Field of Bubbles

2020 ◽  
Vol 8 (2) ◽  
pp. 88 ◽  
Author(s):  
Diana Vargas ◽  
Ravindra Jayaratne ◽  
Edgar Mendoza ◽  
Rodolfo Silva
Keyword(s):  
Time Series ◽  
Free Surface ◽  
High Speed ◽  
Low Cost ◽  
Video Camera ◽  
Surface Elevation ◽  
Irregular Waves ◽  
Air Bubbles ◽  
Digital Video Camera ◽  
Wave Heights

This paper describes a new set of experiments focused on estimating time series of the free surface elevation of water (FSEW) from velocities recorded by submerged air bubbles under regular and irregular waves using a low-cost non-intrusive technique. The main purpose is to compute wave heights and periods using time series of velocities recorded at any depth. The velocities were taken from the tracking of a bubble curtain with only one high-speed digital video camera and a bubble generator. These experiments eliminate the need of intrusive instruments while the methodology can also be applied if the free surface is not visible or even if only part of the depth can be recorded. The estimation of the FSEW was successful for regular waves and reasonably accurate for irregular waves. Moreover, the algorithm to reconstruct the FSEW showed better results for larger wave amplitudes.

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