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A study of the natural ventilation of offshore modules using CFD modelling and on-site measurements
AuthorsJ Saunders
Date published2001
AbstractNatural ventilation can help to maintain safe working conditions on offshore modules by diluting and dispersing gas and vapours. However by its nature its effectiveness is variable and strongly dependent on weather conditions. To understand and quantify the extent of the problem on naturally ventilated modules an approach combining both experimental measurements which were carried out on three platforms and CFD (computational fluid dynamics) applied to one platform is presented. This is followed by some discussion on a comparison of the ventilation in different areas within a module.
AuthorsJ Saunders
Date published2001
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Analysis of horizontal forces acting on vertical walls of perforated breakwater
AuthorsE H Tabet-Aoul ; J-M Rousset ; M Belorgey
Date published1999
AbstractThere is little literature on analysing force development acting on perforated caisson and presenting liable tools for determining design parameters. Based on 2D model tests and field measurement an attempt is made to show the importance of phase difference in appearance of peak horizontal forces on the different faces of the caisson as well as the way in which total force on the whole structure is formed. First a look is taken at a 2D model study of horizontal forces. This is followed by consideration of Dieppe Field measurement.
AuthorsE H Tabet-Aoul ; J-M Rousset ; M Belorgey
Date published1999
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Effect of water deluge on gas dispersion
AuthorsJan Roar Bakke ; Olav Roald Hansen ; Hans-Christen Salvesen et al.
Date published2003
AbstractThe effect of water deluge on gas dispersion is addressed. Experimental research on the effect of deluge on gas dispersion is described. After this CFD simulations of selected tests using FLACS are presented. Then CFD predictions are compared to gas detector recordings from an actual offshore incident. Finally it is concluded that deluge may have a significant effect on gas dispersion as seen through medium-scale experiments as well as through full-scale real leak situations. It is suggested that risk studies for installations for which use of deluge is a likely procedure in gas leak situations should include the modelling of the effect of deluge on dispersion.
AuthorsJan Roar Bakke ; Olav Roald Hansen ; Hans-Christen Salvesen et al.
Date published2003
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Numerical Study of the Hydroelastic Effect on the Impact Loads Due to Bottom Slamming on Ship Structure
AuthorsA Bereznitski ; B Boon ; V Postnov
Date published2000
AbstractA new more exact approach for the problem of impact interaction of a ship structure (ship's frame) with compressible water domain which allows taking into account the structure flexibility is presented. The influence of the ship structure flexibility on hydrodynamic impact loads is studied. In result it is possible to specify better the external loads on the ship structures.
AuthorsA Bereznitski ; B Boon ; V Postnov
Date published2000
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On the risk of structural failure on Norwegian offshore installations
AuthorsArne Kvitrud ; Gerhard Ersdal ; Roger L Leonhardsen
Date published2001
AbstractThe purpose of this paper is to review the worldwide historical structural failure data in the 1990s on offshore structures and compare this with the present risk analyses of Norwegian offshore structures. The paper describes an overview of registered accidents to offshore structures based on the databases WOAD and CODAM. The accident data is given for fixed platforms jack-ups and for floating platforms. Estimates of risk level in annual frequencies and PLL values are given for each platform type.
AuthorsArne Kvitrud ; Gerhard Ersdal ; Roger L Leonhardsen
Date published2001
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The influence of slamming and whipping on the fatigue life of a high-speed catamaran
AuthorsGiles Thomas ; Michael Davis ; Damien Holloway et al.
Date published2005
AbstractThis paper reports on an investigation into the influence of slamming and whipping on the fatigue life of a large high-speed catamaran. Full-scale measurements of slam events were conducted on a 98m Incat catamaran to investigate its slamming behaviour in a variety of sea conditions. The full scale results were then used to determine the influence of the presence of slam events on fatigue life. In addition the effects of significant wave height slam occurrence rates slam peak stresses and whipping behaviour on fatigue life were examined.
AuthorsGiles Thomas ; Michael Davis ; Damien Holloway et al.
Date published2005
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Power prediction for high-speed catamarans from analysis of geosim tests and from numerical results
AuthorsD Bruzzone ; P Cassella ; C Coppola et al.
Date published1999
AbstractExperimental and numerical research is presented which was carried out on a high-speed symmetric catamaran operating in the Gulf of Naples. The experimental research was jointly carried out on three egoisms. It was carried out to obtain indications on scale effects on the resistance components on the influence of the towing line position on the resistance model tests on the most suitable ship-model correlation and on the power prediction scale effect. A theoretical wave pattern analysis was also carried out by means of the application of a numerical panel methodology based on Rankine sources. The results from the numerical wave pattern were compared with the corresponding experimental results obtained by the longitudinal cut method (Sharma 1966). The comparison was carried out in terms of wave resistance wave pattern and free wave spectra. The results of this research may give indications about the power prediction for high-speed catamarans by model tests and by numerical wave pattern analysis.
AuthorsD Bruzzone ; P Cassella ; C Coppola et al.
Date published1999
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Wind loads acting on very large floating structures
AuthorsF Kitamura ; H Sato ; K Shimada et al.
PublisherAmerican Society of Mechanical Engineers - ASME
AbstractA practical method to estimate wind loads on very large floating structures (VLFS) of mat-like shape are proposed based on results of wind tunnel tests. Differences between VLFS and conventional size structures are outlined. Three models are presented: a two dimensional model to investigate characteristics of frictional drag on large deck area considering wind speed profile near the sea surface; a three dimensional model to investigate wind direction influence on total drag as well as pressure distribution on side walls of the structure; and partial models for the structure corners of both convex and concave types to investigate pressure distribution on the side walls around the corners. The method for estimating wind loads is useful in determination of required number and capacity of mooring units.
AuthorsDate publishedF Kitamura ; H Sato ; K Shimada et al.
1997
PublisherAmerican Society of Mechanical Engineers - ASME
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A study on structural design of huge barge structures based on collapsing behaviour and reliability analysis
AuthorsShinji Katsura ; Hiroo Okada ; Koji Masaoka et al.
Date published2003
AbstractThis paper deals with the limit state and reliability analysis of huge barge structures (HBS) which are supposed floating refuse storage and incineration plant based on collapsing behaviour analysis in irregular waves as a part of studies on structural reliability-based design methods. First a limit state and reliability analysis method is shortly presented for the buckling and ultimate collapse strength of deck bulkhead and bottom panels of HBS. Next a simplified method is briefly introduced for collapsing behaviour and reliability analysis of HBS under extreme sea loads by using a developed system combined with a finite element method and plastic node method using hexahedral element models. Moreover a simplified estimation method is shortly introduced for the probabilistic load model considering the hydro-elastic response of the structure in irregular waves. Finally the applicability of the methods is investigated through numerical examples for a 1000m-class HBS under a trial design for some irregular sea-state conditions. Characteristics of the short-term responses and reliability levels are numerically shown.
AuthorsShinji Katsura ; Hiroo Okada ; Koji Masaoka et al.
Date published2003
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About the welding effects on thin stiffened panel assemblies in shipbuilding
AuthorsT T Chau ; F Jancart ; G Bechepay
Date published2001
AbstractThe welding effects on thin stiffened panel assemblies in shipbuilding are examined. The distortion problem is considered. Two thermo-mechanical simulations are carried out on two 3D models of thin stiffened plate panels of a deck and of a bulkhead using a conventional FEM code and the IRCN numerical method. Results show the buckling state reached by the entire bulkhead panel under the effects of V-butt weldings executed on board during the assembly operations. Other applications of the method on thin stiffened plate panels are presented showing the influence of the welding sequence on the residual stresses and initial deflections of such thin plates usually used in shipbuilding.
AuthorsT T Chau ; F Jancart ; G Bechepay
Date published2001
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Effect of corrosion model uncertainty on inspection and repair planning for ship structures
AuthorsLi Dianqing ; Zhang Shengkun ; Tang Wenyong
Date published2004
AbstractA theoretical framework of risk based optimal inspection and repair planning is proposed for the ship structures subjected to corrosion deterioration. The planning problem is formulated as an optimization problem where the expected lifetime costs are minimized with a constraint on the minimum acceptable reliability index. The safety margins are established for the inspection the repair and the failure events for ship structures. moreover the formulae are derived to calculate the failure probability and the repair probability. Based on them two corrosion models namely Paik's model and Guedes Soares' model are adopted to analyze the effect of model uncertainty on the optimal inspection and repair planning for ship structures. The results show that a balance can be achieved betwen the risk cost and total expected inspection and repair costs by using the risk based optimal inspection and repair method which is very effective in selecting the optimal inspection and repair strategy. In addition the uncertainty of corrosion model has a significant influence on the optimal number and the time of inspections and repairs. However it has insignificant influence on the total expected costs and total probability of failure
AuthorsLi Dianqing ; Zhang Shengkun ; Tang Wenyong
Date published2004
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Effects of combination motions on hydrodynamic forces induced on bodies in the sea
AuthorsJ M R Graham ; Y D Zhao ; C Y Zhou et al.
Date published1994
AbstractTwo types of flow around long bodies with a range of cross-sections are examined. The first considers oscillatory flows with two components at right angles to one another with a range of frequency and amplitude ratios. Experimental measurements have been carried out on two pontoon sections undergoing forced motion in two directions in a wave tank. The second is a planar oscillatory flow around a circular cross-section with cycles of varying period and amplitude. This is to examine history effects which occur for fixed cylinders in random waves or risers moving through in-line waves. Both flow types are studied using numerical simulation of the Navier-Stokes equations. Generally very similar effects on the force coefficients result from the computations and the experiments.
AuthorsJ M R Graham ; Y D Zhao ; C Y Zhou et al.
Date published1994
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Experimental and numerical studies on MV Derbyshire
AuthorsDracos Vassalos ; Luis Guarin ; Andrzej Jasionowski
Shelf Location213c
AbstractA systematic experimental and numerical investigation is presented which was carried out to provide evidence to be used in judgement of a number of hypothesis put forward by various parties on the loss of MV Derbyshire. This work was conducted in parallel to an experimental research programme on the safety of bulk carriers in extreme seas. Many of the issues dealt with during the investigation were relatively unknown. Sea keeping model tests were undertaken in extreme sea states in which green seas impact loads on the hatch covers and coamings were characterised. Analytical and numerical studies integrating the results of sea keeping and structural analysis were focused on the assessment of various sinking scenarios. Virtual reality technology was used to present and illustrate the findings. The objectives assumptions and methods adopted during the investigation are summarised and the finding s are presented with emphasis on those issues identified as relevant for drawing recommendations for bulk carriers design and for systematising forensic investigations in maritime accidents.
AuthorsDate publishedDracos Vassalos ; Luis Guarin ; Andrzej Jasionowski
2002
Shelf Location213c
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From sea to space a perspective on the effect of subsea remote intervention techniques on space station design
AuthorsG Hughes ; M Gittleman
Date published1997
AbstractThe decision by Oceaneering International to try to apply the lessons learned through thirty years of successful subsea operations to space particularly to the space station program has led to the creation of Oceaneering Space Systems (OSS). The increasing reliance on a teleoperated worksystem (ROVs and remote tooling) mirrors the assembly and maintenance operations planned for the International Space Station (ISS) program. The equipment and operational philosophy behind remote intervention in both subsea and space are compared. The impact of technology transfer on both industries is looked into.
AuthorsG Hughes ; M Gittleman
Date published1997
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Ice loads on a model podded propeller blade in milling conditions
AuthorsJungyong Wang ; Ayhan Akinturk ; Stephen J Jones et al.
Date published2005
AbstractPropeller-ice interaction experiments were conducted in the ice tank at the National Research Council of Canada's Institute for Ocean Technology. A podded propeller was used in "Puller" mode and loads on an instrumented blade were measured. During the propeller-ice interaction hydrodynamic loads and ice milling loads were acting on the propeller blade. This paper focuses on the ice milling loads both in water and in air. The non-dimensional ice milling loads including inseparable hydrodynamic loads on the blade are presented against advance ratio with varied depths of cut. The results help to reduce the gap of knowledge for interaction between ice and propeller and give information about significant variables acting on the propeller blade during interaction.
AuthorsJungyong Wang ; Ayhan Akinturk ; Stephen J Jones et al.
Date published2005
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Impurity effects on pore formation at Al2O3-alloy interfaces
AuthorsP Y Hou
Date published2003
AbstractThe adhesion of Al2O3 scales on commercial grade alloys that do not contain a reactive element is usually poor due to the presence of 10-50 wppm of sulphur impurity and-or of pores that formed at the scale-alloy interface. The effect of impurities on pore nucleation and growth is evaluated. Sulphur in the alloy as well as possible surface contaminates are considered. Sulphur is usually believed to segregate to the interface to weaken the interfacial bonding and to stabilise interfacial pores. By using field emission scanning Auger microscopy the distribution of sulphur on pores and on oxide-imprinted areas at Al2O3-FeAl interfaces is precisely determined. Interfacial pore growth as a function of oxidation time was obtained from SEM (scanning electron microscopy) and AFM (atomic force microscopy) analyses. The effects of sulphur segregation surface impurity and reactive elements on pore nucleation and growth are discussed.
AuthorsP Y Hou
Date published2003
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Maritime traffic effects on biodiversity in the Mediterranean Sea : Volume 2 - legal mechanism to address maritime impacts on Mediterranean biodiversity
Authorseditors: Nilufer Oral ; Francois Simard
Shelf Location232d
AbstractTo examines the impact of shipping on marine biodiversity in the Mediterranean Sea, a workshop was convened in Istanbul in September 2007. One of the most important outcomes of the workshop was the preparation of four background papers outlining the legal framework and the measures available within this framework. These papers have been collected together in this volume. Chapters include an overview of opportunities under the law of the sea to improve marine environmental conservation affected by maritime traffic; a review of global experience with particularly sensitive sea areas (PSSAs); the application of international measures for the protection of the marine environment from the impacts of shipping; and maritime traffic, marine biodiversity and the Green Paper on a future Maritime Policy for the EU.
AuthorsPublishereditors: Nilufer Oral ; Francois Simard
International Union for Conservation of Nature and Natural Resources
ISBN number9782831710808
Shelf LocationDate published232d
2008
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Report on the use of PLUTOcen-F on 'Lilac' owned by Shin-Nihonkai Ferry
AuthorsH Shimizu
Date published2000
AbstractThe fuel improver PLUTOcen-F is used on a subject vessel and its performance is reported. The active compound incorporated in PLUTOcen products is the ironorganic compound ferrocene. It is reported that fuel combustion improves and soot is reduced as well as the physical structure of soot being changed to a dryer softer structure. The effect of its use is to minimise wear on piston rings and cylinder line and to reduce consumption of system oil and to keep clean the nozzle ring the blade of T-C the combustion chamber of M-E boiler and EGE.
AuthorsH Shimizu
Date published2000
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Sampling variance of species identification in fisheries-acoustic surveys based on automated procedures associating acoustic images and trawl hauls
AuthorsPierre Petitgas ; Jacques Masse ; Pierre Beillois et al.
Date published2002
AbstractIn this paper the sampling variance of species identification is developed and automated procedures are used allowing energy allocation to be carried out by a non-expert. The procedures are based on the fact that at the sampling stage trawl hauls are linked with particular acoustic images. The procedures have two steps: the classification step corresponds to species identification and the aggregation step to energy allocation. Classification is performed on the identified images. Aggregation is performed on non-identified images and results in post-stratifying the data. The estimation is then derived automatically and is conditioned by the post-stratification. Two approaches are followed one based on the echo-trace characteristics making full use of the echogram (acoustic-image classification) and the other on the spatial continuity of the species composition between trawl hauls (trawl-haul classification). These methods are described and compared.
AuthorsPierre Petitgas ; Jacques Masse ; Pierre Beillois et al.
Date published2002
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Some environmental considerations and their influence on the design and operation of ships
AuthorsJohn S Carlton
PublisherIMarE (Sydney)
AbstractFollowing a brief review of the significance of the marine contribution to air pollution on both a local and global scale the paper then considers the influence that emission controls are likely to have on ship design and operation in the future. Legislation is likely to be introduced on an international scale to limit the oxides of nitrogen and sulphur consequently these emissions are considered first in the paper. In the case of NOx emissions both primary and secondary methods are reviewed and the various implications of the direct and indirect methods of verification of compliance with emission regulations are discussed. Following this the implications of fuel sulphur levels in terms of their influence on SOx production abatement technologies and their implications for particulate emissions are considered. The paper then discusses the influence of ship design machinery selection and operational modes on emission species in general; paying attention to the CO CO2 and HC species as well as those previously considered. Finally the implications of introducing abatement technology onboard ships in terms of manning and ship operation are examined.
AuthorsDate publishedJohn S Carlton
1995
PublisherIMarE (Sydney)