Design Aspects of Green Water Loading on FPSOs

2003 ◽  
Author(s):  
Bas Buchner ◽  
Joaqui´n Lopez-Cortijo Garcia
Keyword(s):  
Evaluation Method ◽  
Offshore Structures ◽  
Green Water ◽  
Evaluation Procedure ◽  
Design Evaluation ◽  
Water Impact ◽  
Advantages And Disadvantages ◽  
Water Problem ◽  
Semi Empirical ◽  
Empirical Design

Green water is a significant problem for floating ship-type offshore structures, which needs to be assessed in the early design of the structure. First the present paper summarises a new semi-empirical design evaluation procedure that can assist in this design process. Then the practical design considerations related to the green water problem are discussed. There are different ways to solve the green water problem for a particular structure at a specific location: • Design the vessel and structures on the deck against the predicted green water impact load levels. • Optimise the bow shape (underwater shape and above water bow flare). • Increase the freeboard height such that green water is prevented completely. • Increase the freeboard height such that the green water loads are reduced to acceptable levels and design for these load levels. • Optimise the structures on the deck to minimise the green water impact loads. • Use protecting breakwaters in front of critical structures on the deck. All these options have their advantages and disadvantages. The semi-empirical design evaluation method and the different design options are discussed in a case study, focussing on a new DP FPSO concept.

Use of Wet Dam-Break to Study Green Water Problem

2017 ◽  
Author(s):  
Jassiel V. Hernández-Fontes ◽  
Marcelo A. Vitola ◽  
Monica C. Silva ◽  
Paulo de Tarso T. Esperança ◽  
Sergio H. Sphaier
Keyword(s):  
High Speed ◽  
Good Practice ◽  
Offshore Structures ◽  
Dam Break ◽  
Irregular Waves ◽  
Green Water ◽  
Incoming Wave ◽  
Water Problem ◽  
Different Types ◽  
Fixed Structure

Green water occurs when an incoming wave exceeds the freeboard and propagates on the deck of naval/offshore structures, such as FPSO’s and platforms. The water on deck can affect the integrity of facilities and equipments installed on it, compromise the safety of the crew and affect the dynamic stability of the structure. Traditionally, regular or irregular waves generated by different types of wave-makers have been used to reproduce green water events. This is a good practice to study consecutive events. However, to study isolated events, an alternative could be the use of the wet dam-break approach to generate the incoming flow. The purpose of this paper is to investigate experimentally the use of the wet dam-break approach to generate isolated green water events. Tests were carried out in a rectangular tank with a fixed structure. Different freeboard conditions were tested for one aspect ratio of the wet dam-break (h0/h1 = 0.6). High speed cameras were used to investigate the initial phases of green water. Results demonstrated the ability of this approach to represent different types of green water events.

State-of-the-Art of Green Water on FPSO in Harsh Environment

2011 ◽  
Vol 464 ◽  
pp. 465-468
Author(s):  
Tao Ni ◽  
Yun Wang ◽  
Bing Nan Li ◽  
Shen Tao Tang ◽  
Yong Kang Zhang
Keyword(s):  
State Of The Art ◽  
Single Point ◽  
Offshore Structures ◽  
Green Water ◽  
Harsh Environment ◽  
Mooring System ◽  
Wave Runup ◽  
Auxiliary Equipment ◽  
Forming Mechanism ◽  
Water Problem

The phenomena of green water are the maximum vertical extent of wave uprush over freeboard on the deck with the result of damage to the deck, bow and auxiliary equipment. The FPSO with Single-point mooring system or disconnectable mooring system always operates in the severe deepwater or ultra-deepwater environment such as Gulf of Mexico or Southeast Asia, which should be allowed to weathervane. Therefore, FPSO is always exposed to wave runup and overtopping. Nowadays green water problem has become one of the most important factors to endanger offshore structures, such as FPSO, TLPs and SPARS. This paper gives a comprehensive review of the state-of-the-art in green water, including the forming mechanism, numerical simulation and model test of wave runup. Finally the prospect of simulating green water is discussed.

On the Generation of Isolated Green Water Events Using Wet Dam-Break

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Jassiel V. Hernández-Fontes ◽  
Marcelo A. Vitola ◽  
Monica C. Silva ◽  
Paulo de Tarso T. Esperança ◽  
Sergio H. Sphaier
Keyword(s):  
High Speed ◽  
Offshore Structures ◽  
Dam Break ◽  
Water Levels ◽  
Green Water ◽  
Incoming Wave ◽  
Aspect Ratios ◽  
Water Problem ◽  
Different Types ◽  
Wave Trains

Green water occurs when an incoming wave exceeds the freeboard and propagates onto the deck of naval/offshore structures, such as floating production storage and offloading units and platforms. This water can affect the integrity of facilities and equipment that are installed on the deck, compromise the safety of the crew, and affect the dynamic stability of the structure. Traditionally, wave trains have been used to study the green water problem, which is a good approach to analyzing consecutive green water events. However, to carry out systematic studies that allow local details to be identified for different types of green water, an alternative method is to study isolated events generated by a single incoming wave. The purpose of this paper was to experimentally investigate the generation of different types of isolated green water events using the wet dam-break (DB) approach as an alternative to generating the incoming wave. Tests were carried out in a rectangular tank with a fixed internal structure. Different freeboard conditions were tested for two aspect ratios of the wet DB (h0/h1=0.40 and 0.6). Conventional wave probes were used to measure the water levels in the tank, and a high-speed camera was set to capture details of the generated green water events. The results demonstrated the ability of this approach to represent different types of green water, similar to those obtained with unbroken regular waves in barge-shaped fixed structures, including DB, plunging-dam-break (PDB) and hammer-fist (HF).

Bewertung lichter Wälder im Kanton Zürich und der Nutzen für das Projektmanagement | Evaluation of open forest in Canton Zurich and its significance for project management

2006 ◽  
Vol 157 (8) ◽  
pp. 303-309
Author(s):  
René Bertiller ◽  
Andreas Keel ◽  
Hans-Peter Stutz
Keyword(s):  
Project Management ◽  
Animal Species ◽  
Evaluation Method ◽  
Advantages And Disadvantages ◽  
Open Forest ◽  
Open Forests ◽  
Initial Results ◽  
The Way

In 2004, the canton of Zurich possessed 376 hectares of uninterrupted open forest. Such stretches of forest provide essential habitats for animal species that favour both light and heat. Standardised surveys, and available data relative to existing flora and fauna has greatly facilitated the evaluation of the forest's vegetation and inhabitants. This contribution presents both the methods used, and the initial results. The advantages and disadvantages of the so called LiWa-indicator are discussed,and the way this evaluation method can be used to manage the plan of action entitled «Open forests in Canton Zurich»is illustrated.

Computation of the Bow Deck Design Pressure against the Green Water Impact

2019 ◽  
Vol 56 (4) ◽  
pp. 343-351
Author(s):  
Yong Jig Kim ◽  
Ki-Seok Shin ◽  
Seung-Chul Lee ◽  
Youngrok Ha ◽  
Sa Young Hong
Keyword(s):  
Green Water ◽  
Water Impact ◽  
Design Pressure

scholarly journals A Multi-Objective Particle Swarm Optimization for Trajectory Planning of Fruit Picking Manipulator

Agronomy ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2286
Author(s):  
Xiaoman Cao ◽  
Hansheng Yan ◽  
Zhengyan Huang ◽  
Si Ai ◽  
Yongjun Xu ◽  
...  
Keyword(s):  
Particle Swarm Optimization ◽  
Energy Consumption ◽  
Evaluation Method ◽  
Technical Problem ◽  
Particle Swarm ◽  
Optimal Solution ◽  
Swarm Optimization ◽  
Multi Objective ◽  
Advantages And Disadvantages ◽  
Optimal Evaluation

Stable, efficient and lossless fruit picking has always been a difficult problem, perplexing the development of fruit automatic picking technology. In order to effectively solve this technical problem, this paper establishes a multi-objective trajectory model of the manipulator and proposes an improved multi-objective particle swarm optimization algorithm (represented as GMOPSO). The algorithm combines the methods of mutation operator, annealing factor and feedback mechanism to improve the diversity of the population on the basis of meeting the stable motion, avoiding the local optimal solution and accelerating the convergence speed. By adopting the average optimal evaluation method, the robot arm motion trajectory has been testified to constructively fulfill the picking standards of stability, efficiency and lossless. The performance of the algorithm is verified by ZDT1~ZDT3 benchmark functions, and its competitive advantages and disadvantages with other multi-objective evolutionary algorithms are further elaborated. In this paper, the algorithm is simulated and verified by practical experiments with the optimization objectives of time, energy consumption and pulsation. The simulation results show that the solution set of the algorithm is close to the real Pareto frontier. The optimal solution obtained by the average optimal evaluation method is as follows: the time is 34.20 s, the energy consumption is 61.89 °/S2 and the pulsation is 72.18 °/S3. The actual test results show that the trajectory can effectively complete fruit picking, the average picking time is 25.5 s, and the success rate is 96.67%. The experimental results show that the trajectory of the manipulator obtained by GMOPSO algorithm can make the manipulator run smoothly and facilitates efficient, stable and nondestructive picking.

scholarly journals Study on Home Chairs Design Evaluation for Low-and Middle-income Groups Based on User Experience

2020 ◽  
Vol 8 (01) ◽  
pp. 307-313
Author(s):  
Xianshu Leng ◽  
Hong Zhang ◽  
Ding Feng
Keyword(s):  
User Experience ◽  
Evaluation Method ◽  
Emotional Experience ◽  
Sensory Experience ◽  
Living Environment ◽  
Design Evaluation ◽  
Middle Income ◽  
Income Groups ◽  
Economic Experience ◽  
Low And Middle Income

Pay attention to the home living environment of low-and middle-income groups, study the user-centered design evaluation method to guide the design of home chairs suitable for low-and middle-income groups. Introducing Analytic Hierarchy Process（AHP）into home chairs’ design evaluation, it establishes a different layer and different elements structure model based on sensory experience, behavioral experience, emotional experience and economic experience from the point of user experience. Scoring each element, it calculates and determines the weight value of every element, and forms an evaluation method of home chairs for low-and middle-income Groups. Using the method to evaluate the design schemes of 3 home chairs, it obtains the optimal scheme. Then, surveying the market sales data to verify the accuracy of the result. The evaluation method consists of four major elements: sensory experience(B1), 27%; behavior experience(B2), 41%; emotional experience(B3), 10%; economic experience(B4), 22%. The method can effectively solve the complex comparison of multiple elements in design evaluation and provide a comprehensive method combining qualitative and quantitative methods for product design, and provides reference for products design and evaluation of the same type

Toward Limit State Design of Ships and Offshore Structures Under Impact Pressure Actions: A State-of-the-Art Review

2006 ◽  
Vol 43 (03) ◽  
pp. 135-145
Author(s):  
Jeom Kee Paik
Keyword(s):  
Limit State ◽  
Structural Response ◽  
Time History ◽  
Rate Sensitivity ◽  
Offshore Structures ◽  
Impact Pressure ◽  
Green Water ◽  
Limit State Design ◽  
Structural Capacity ◽  
Pressure Time

In design of ships and ship-shaped offshore units, issues related to impact pressure actions arising from sloshing, slamming, green water, or explosion are of particular concern. The structural response under impact pressure actions is quite different from that under static or quasistatic actions. It has been recognized that the limit state approach is a more rational basis for structural design and safety assessment where both "demand" (loads) and "capacity" (strength) must be accurately defined. For impact pressure action cases, the demand is associated with hydrodynamics areas, taking into account the characteristics of impact pressure-time history, and the structural capacity is associated with structural mechanics areas, considering geometric and material nonlinearities together with strain rate sensitivity. This paper reviews recent advances and trends toward future limit state design of ships and offshore structures under impact pressure actions.

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