ISP Volume 67, issue 1 of 2020, is an issue that contains five articles on the application of hydrogen in the maritime world. Summaries, as well as the full articles can be found on https://content.iospress.com/journals/international-shipbuilding-progress/67/1.

Designing the zero emission vessels of the future: Technologic, economic and environmental aspects

Authors:  B. Mestemaker, H. van den Heuvel and B. Gonçalves Castro

Abstract

One of the major challenges facing the maritime sector today is the transition to zero emission carbon-neutral vessels. In particular, work vessels such as dredging vessels are required to operate worldwide and under heavy conditions. These vessels have a high power density, limited on-board space, require often a large autonomy, and therefore will need very energy dense fuels. This article presents an environmental and economic assessment of four cutter suction dredger drive system design alternatives with the life cycle performance assessment tool. This tool includes the most important environmental factors as well as the net present value. The effect of emission costs and fuel price developments may be taken into account with scenarios, and this article illustrates that they have a large effect on the economic viability of future zero emission vessels. A combination of clean fuels, new prime mover technologies, efficient design and effective system integration has the potential to achieve zero emissions while maintaining the vessels’ functionality. However, technology alone cannot solve the complex challenge of energy transition in the maritime sector. In order to make zero emission designs economically viable, a system wide integration is needed, meaning cooperation in the value chain and effective policies. 

High energy storage of gaseous marine fuels: An innovative concept and its application to a hydrogen powered ferry

Authors:  R. Taccani, S. Malabotti, C. Dall’ Armi and D. Micheli

Abstract

The upcoming stricter limitations on both pollutant and greenhouse gases emissions represent a challenge for the shipping sector. The entire ship design process requires an approach to innovation, with a particular focus on both the fuel choice and the power generation system. Among the possible alternatives, natural gas and hydrogen based propulsion systems seem to be promising in the medium and long term. Nonetheless, natural gas and hydrogen storage still represents a problem in terms of cargo volume reduction. This paper focuses on the storage issue, considering compressed gases, and presents an innovative solution, which has been developed in the European project GASVESSEL® that allows to store gaseous fuels with an energy density higher than conventional intermediate pressure containment systems. After a general overview of natural gas and hydrogen as fuels for shipping, a case study of a small Roll-on/Roll-off passenger ferry retrofit is proposed. The analysis points out that the filling process is critical to maximize the stored hydrogen mass and that it is critical to measure the temperature of the cylinder walls in order not to exceed the material limits. Nevertheless, for specific application such as the one considered in the paper, the introduction of gaseous hydrogen as fuel, can be considered for implementing zero local emission propulsion system in the medium term.

Maritime fuel cell applications: A tool for conceptual decision making

Authors:  B. Diesveld and E. de Maeyer

Abstract

The environmental impact of ships needs to be reduced by using more sustainable and cleaner solutions for power generation on board to meet the increasing amount of regulations. Fuel cells are seen as one of the most promising solutions to address this challenge. There are various fuel cell technologies which can be combined with different fuel types, resulting in a large number of options. In order to find the best prospect, a review of the fuel and fuel cell technologies is performed to get an understanding of the possibilities and applicability of fuel cells on superyachts. Various systems were compared on the following characteristics: density, storage type, maturity, safety, and emissions. Based on these characteristics a decision-making tool was developed to assist in the decision-making process considering of many variables. Using this tool, it has become clear that a fuel cell solution should be specifically selected for any different type of application. The required applications or required usage of a fuel cell could lead to the selection of a completely different type of technology.

Zero carbon propulsion in shipping – scenarios for the development of hydrogen and wind technologies with the MATISSE-SHIP model

Authors:  J. Köhler

Abstract

This paper introduces the MATISSE-SHIP model for illustrative long term scenarios of technical change in shipping. It applies current theory for sustainable innovation – ‘transition theory’ – and uses an agent-based modelling (ABM) approach that explicitly represents a range of decision makers with different decision criteria. It models investment decisions for new ships, concentrating on the choice of power train and generates time paths of shares of a range of propulsion technologies. Two scenarios were generated to illustrate pathways under which hydrogen achieves a major market in shipping by 2050: 1) If current SOx /NOx legislation does not lead to the large scale adoption of LNG and there is an expectation of strengthened climate change policy in the medium term, wind/H2 combined power systems take off, as they can demonstrate cost savings with GHG emissions reductions. The need for high power applications may lead to the uptake of biofuels as they can provide significant reductions in GHG emissions, while not requiring new bunker infrastructure or changes in operating patterns. 2) If, in addition to these developments, there is acceptance of changes in operations towards lower speeds in container shipping and biofuels remain limited in their adoption (e.g. due to limited supply and high fuel costs), combined wind/H2 propulsion systems could be the main alternative to 2050. High power installations are then covered by fossil fuels to 2050, with Power to Gas/Liquid technologies being developed in the longer term.

Energy and cost analysis of a hydrogen driven high speed passenger ferry

Authors:  F.G. Aarskog, J. Danebergs, T. Strømgren, Ø. Ulleberg

Abstract

Norway is facing the challenge of reducing transport emissions. High speed crafts (HSC) are the means of transport with highest emissions. Currently there is little literature or experience of using hydrogen systems for HSC. Objective: Evaluate the economic feasibility of fuel cell (FC) powered HSC vs diesel and biodiesel today, and in a future scenario, based on real world operation profile. Method: Historical AIS position data from the route combined with the speed-power characteristics of a concept vessel was used to identify the energy and power demand. From the resulting data a suitable FC system was defined, and an economic comparison made based on annual costs including annualized investment and operational costs. Results: HSC with a FC-system has an annual cost of 12.6 MNOK. It is 28% and 12% more expensive than diesel and biodiesel alternative, respectively. A sensitivity analysis with respect to 7 key design parameters indicates that highest impact is made by hull energy efficiency, FC system cost and hydrogen fuel cost. In a future scenario (2025–2030) with moderate technology improvements and cost development, the HSC with FC-systems can become competitive with diesel and cheaper than biodiesel. Conclusions: HSC with FC-systems may reach cost parity with conventional diesel in the period 2025–2030.

ISP Volume 66, issue 4 of 2019, contains four articles. Two of these treat the application of RANS-VoF (Volume of Fluid) modelling. It has been applied to model  air lubrication of ship hulls, and to investigate the effect of air pockets on the development of hydrodynamic impact pressures by green water. The two other articles are on sloshing loads on a LNG cargo containment system, and on a control strategy for combined DP station keeping and active roll reduction, respectively. Summaries, as well as the full articles (all open access)  can be found on https://content.iospress.com/journals/international-shipbuilding-progress/66/4.

Exploring the limits of RANS-VoF modelling for air cavity flows

Authors:  G. Rotte, M. Kerkvliet and T. van Terwisga

Abstract

Air lubrication techniques have the potential to significantly reduce frictional drag, benefiting sustainable employability of ships. This article aims to explore the limitations and capabilities of RANS-VoF (Volume of Fluid) modelling to numerically model air cavity flows like typically would exist below a ship’s hull. Simulations were performed including numerical uncertainty verification and compared to experimental data for an external air cavity. The simulated velocity profiles at different stream-wise locations in the boundary layer around the cavity compare well to the experimental profiles. However, a mismatch was found in the determination of the required air flow rate for the cavity, which is hypothesized to be mainly caused by the incorrect turbulence modelling around the interface and the advection of a smeared air-water interface in the reattachment zone. This is a direct consequence of the used VoF method. The exact mechanism for air discharge at the cavity closure is still not clear.

A reduced order model for structural response of the Mark III LNG cargo containment system

Authors:  R.W. Bos, J.H. den Besten and M.L. Kaminsky

Abstract

Highly varying sloshing loads are a superposition of load components resulting from a sequence of different physical phenomena. However, not all features of spatial and temporal variations of sloshing loads and associated phenomena are equally important when failure of the structure is considered. Therefore, the prediction of sloshing loads should be focused on those load components which lead to failure. These components can be found by employing a structural model, which should be fast computationally considering the huge number of possible sloshing loads. This paper presents a reduced order model based on the beam-foundation model which is derived for the Mark-III cargo containment system. The model is validated against a detailed finite element model and it conservatively predicts the stresses at failure locations. The calculation time using the model is approximately two orders shorter in comparison to a finite element model computation, which allows the model to be applied for finding governing load components and associated physical phenomena.

A compressible two-phase flow model for pressure oscillations in air entrapments following green water impact events on ships

Authors:  M. van der Eijk and P.R. Wellens

Abstract

A significant part of all structural damage to conventional ships is caused by complex free-surface events like slamming, breaking waves, and green water. During these events air can be entrapped by water. The focus of this article is on the resulting air pockets affecting the evolution of the hydrodynamic impact pressure that loads the ship’s structure. In this study the COMFLOW method has been applied, which is an efficient method based on the Navier–Stokes equations with a Volume-of-Fluid approach for the free surface. It has been extended with a Continuum Surface Force (CSF) model for surface tension. The implementation was verified with benchmark cases and validated by means of a dam-break experiment, a characteristic model for green water impact events. Surface tension was found not to have an influence on entrapped air pocket dynamics of air pockets with a radius larger than 0.08 [m]. For wave impacts it was found that the effect of compression waves in the air pocket dominates the dynamics and leads to pressure oscillations that are of the same order of magnitude as the pressure caused by the initial impact on the base of the wall. The code is available at: https://github.com/martin-eijk/2phase.git

A control strategy for combined DP station keeping and active roll reduction

Authors:  R.G. de Jong, T.G. Vos, R. Beindorff and P.R. Wellens

Abstract

Dynamic positioning (DP) systems are used for station keeping during offshore operations. The safety and operability of several offshore operations can be increased when the roll motion is actively controlled, especially in beam seas. A novel control strategy for combined roll motion control and station keeping is proposed, using only the installed DP thrusters. The control strategy is applied to an offshore construction vessel and the performance is demonstrated by time domain simulations. The DP footprint is compared to a conventional dynamic positioning control model. The proposed control model enables active roll reduction while the station keeping performance remains unaffected. The code has been made open source and is available on https://github.com/pwellens/3dp.git

ISP Volume 66, issue 3 of 2019, contains articles on slamming loads on wave piercing catamarans, on the relation between seabed stiffness and fatigue life of catenary risers under wave loads, and on continuous hull monitoring by E-inspection.  Summaries, as well as the full articles can be found on https://content.iospress.com/journals/international-shipbuilding-progress/66/3

Wet-deck slamming loads and pressures acting on wave piercing catamarans

Authors:  B. Shabani, J. Lavroff, D.S. Holloway, M.R. Davis and G.A. Thomas

Abstract
The wet-deck height and centre bow configuration in wave piercing catamarans are critical design factors which influence slamming occurrence and severity.
In this paper, the wet-deck slamming loads and pressures acting on a 112 m catamaran with a centre bow were investigated in regular waves in two wave heights.
A 2.5 m hydroelastic model with three alternate configurations of wet-deck vertical clearance was tested at a speed of 2.89 m/s (38 knots full-scale equivalent).
The results showed that at the instant of slamming the centre bow immersion depth relative to the undisturbed incident wave elevation was less than two thirds of the maximum immersion depth during the wet-deck slam event.
The location of maximum slamming pressure was found to be in the range between 77% and 80% of the overall length from the transom.
The relationship between the relative velocity at impact and slamming force indicated that slamming loads in the order of the vessel weight can occur for the parent design when the relative velocity at slam is about a quarter of the forward speed.
Overall, increasing the wet-deck height was more beneficial for reduction of slamming loads and pressures in smaller waves than in large waves.

Effect of seabed stiffness on fatigue life of steel catenary risers due to random waves

Authors: A. Taheri and M. Alizadeh

Abstract

Today’s oil and gas industry is facing deeper waters and harsher environmental conditions. Offshore platforms and marine risers, as the main parts of this industry, have many challenges and design issues. Steel Catenary Riser (SCR) connected to Floating, Production, Storage, and Offloading unit (FPSO), is a preferred and commonly used solution to the challenges. It is needed to have more understandings of SCR behavior. So in this study, the significance of SCR-seabed interaction is investigated. Also, the effect of seabed stiffness on the structural behavior of the SCR is studied. Results show that the seabed stiffness makes considerable differences in dynamic and fatigue responses of SCRs in the touch down zone (TDZ) and reveal the importance of proper seabed stiffness modeling. Model (I), which represents weak soils with very low stiffness, could resist on continuously applied harsh environmental condition for 139.6 days. Model (IV) which represents a very stiff seabed, had a minimum fatigue life of about 6.5 percent of the model (I). The results indicated that the SCR responses were highly separated in terms of fatigue performance especially for weak to normal soils.

E-inspection: effect of continuous hull monitoring on ship safety and crew workload

Authors: P. Antão, M. Hoogeland, A.W. Vredeveldt and F.P. Santos

Abstract

Crewmembers are exposed to high work pressure. Pressure on freight tariffs motivates cost reduction in manning and maintenance, whilst societal developments show decreasing tolerances towards incidents. In conjunction with the developments towards autonomous shipping, the need for continuous and unmanned inspection increases. Considerable progress had been made with respect to monitoring machinery condition, however, the hull structure is as relevant for inspection and maintenance. This will require enhanced inspection, i.e., E-inspection. For hull structure corrosion and fatigue are of main interest. The applica- tion of E-inspection, directs the work effort from the crew to the location of interest, at the right time. It gives also the option to monitor the health status of a ship from shore. This paper summarizes the E- inspection methods and how they will help the crew reducing inspection workload.

ISP Volume 66, issue 2 of 2019, contains articles on ship added resistance in waves, optimization of thruster locations on offshore vessels, application of plastics for non-structural components of marine engines as well as an article on distributed energy resources in cruise ships. 

More extensive summaries, as well as the full articles can be found on https://content.iospress.com/journals/international-shipbuilding-progress/66/2

Experimental assessment of effects of bow-wave breaking on added resistance for the fast ship

Authors: B. Choi, P.R. Wellens and R.H.M. Huijsmans

Abstract

The linear relationship between the pressure and the relative wave elevation on the hull surface is a prominent factor to be reconsidered in relation to the uncertainty of the added resistance. An evaluation method is proposed to access the nonlinear relationship between the hull pressure and the relative wave elevation, which has a decisive influence on the added resistance evaluation. This method is used to experimentally investigate the effect of bow-wave breaking of the fast displacement ship in waves. The results show that the nonlinearity between relative wave elevation and hull surface pressure due to the plunging breaking of a bow wave is intuitively detected using the proposed analytical tool. This study provides important insight into the nonlinear relationship between relative wave elevation and added resistance. In addition, the findings provide a better understanding of the process of plunging breaking of bow waves.

This publication is available at IOS Press through this link

Optimal thruster location on offshore DP vessels

Authors: F. Mauro and P. Nabergoj

Abstract

During a design- or conversion process of an offshore vessel, the DP system is usually not one of the primary constraints for the general arrangement of the vessel. Usually the location of the thrusters is driven by the available internal spaces, i.e. the thruster positions are not optimized to the maximum capability. Therefore, it is considered worthwhile to study in more detail thruster arrangements aimed to maximize the capability of the vessel to keep position with a certain amount of installed power. In the present work a procedure aimed to find optimal thruster locations on the hull during the early design stage is presented. Using a quasi-static approach for DP capability evaluation, an optimization procedure based on a genetic algorithm has been developed, considering the constraints given by the vessel geometry. The method is applied to a test case, being a typical offshore vessel, where the original layout is compared with two possible optimized configurations.

This publication is available at IOS Press through this link

Design of non-structural components for marine engines based on nano-engineered thermoplastic polymers

Authors: S. Bertagna, E. Laurini, A. Mannò, C. Nasso, S. Pricl and V. Bucci

Abstract
During a design- or conversion process of an offshore vessel, the DP system is usually not one of the primary constraints for the general arrangement of the vessel. Usually the location of the thrusters is driven by the available internal spaces, i.e. the thruster positions are not optimized to the maximum capability. Therefore, it is considered worthwhile to study in more detail thruster arrangements aimed to maximize the capability of the vessel to keep position with a certain amount of installed power. In the present work a procedure aimed to find optimal thruster locations on the hull during the early design stage is presented. Using a quasi-static approach for DP capability evaluation, an optimization procedure based on a genetic algorithm has been developed, considering the constraints given by the vessel geometry. The method is applied to a test case, being a typical offshore vessel, where the original layout is compared with two possible optimized configurations.

This publication is available at IOS Press through this link

Shipboard distributed energy resources: Motivations, challenges and possible solutions in the cruise ship arena

Authors: A. Boveri, G.A, Di Mare, D. Rattazzi, P. Gualini, L. Magistri and F. Silvestro

Abstract
Metallic alloys play a leading role in marine engine construction. To reduce cost and weights, there is a constant need for new, high-performance materials for the production of non-structural components of marine engines. Nano-engineered thermo-plastic polymers (NETP’s) are ideal alternatives, allowing for additional benefits (e.g. simplified maintenance and inspection operations). The application of plastic-based materials also contributes to environmental sustainability, both in terms of component production process and recyclability. The use of these materials in marine engine design requires computer multiscale simulations to tailor-fit their molecular structure in order to achieve the expected performances required by specific, advanced functions. For the introduction of non-structural plastic components in marine engines a specific rule framework still has to be defined.  In this paper a certification procedure is proposed and applied to the case of plastic cylinder head cover, starting from the analysis of the rule framework currently used for metallic alloys.

This publication is available at IOS Press through this link

ISP Volume 66, issue 1 of 2019, contains 6 articles on various topics.
This is a special issue, containing extended versions of selected papers of the NAV2018 conference held in Trieste, Italy in June 2018. It contains various articles on ship strength, design and construction aspects as well as an article on numerical
investigations of a cavitating propeller.
More extensive summaries, as well as the full articles can be found via this link

Comparative study between analytical and FE analysis for the ultimate strength assessment of pitted platings

Authors: V. Piscopo and A. Scamardella
Abstract:

The ultimate strength assessment of platings affected by pitting corrosion wastage is a basic issue for the scantling and design of ship structures. In the past, several non-linear FE analyses were performed to investigate the incidence of pitting degree and corrosion depth on the ultimate strength of plate panels, with the main aim of providing some approximate formulations, useful at least in the preliminary project phase.
Based on actual state of art, the main aim of current research is to provide an analytical formulation for the ultimate strength assessment of platings with random pitting corrosion wastage, by solving the Marguerre non-linear governing
differential equations for large deflection analysis of platings in the post-buckling
regime. In this respect, a comparative analysis between the analytical solution and a series of FE results is preliminarily performed for uncorroded platings, combining different levels of initial geometrical imperfections and welding residual stresses.
Subsequently, the comparative analysis is extended to platings affected by pitting corrosion wastage. Hence, different levels of pitting and corrosion intensity degrees are properly combined in order to investigate the goodness of the proposed analytical formulation.

This publication is available at IOS Press through this link

Mechanical buckling analysis of explosive welded joints used in shipbuilding

Authors: P. Corigliano, V. Crupi and E. Guglielmino
Abstract:
Aluminum superstructures and steel hull connections are of fundamental importance in ships.This study regards the buckling analysis of explosion welded joints, made of three layers (ASTM A516 low carbon steel, pure aluminium, A5086 aluminium alloy) and used in ship structures. Tensile and compressive tests were carried out on explosion welded specimens. The Infrared Thermography was used to detect the superficial temperature of the specimen during the tensile test and three phases of the temperature evolution were observed. The Digital Image Correlation technique was applied during the tests for the detection of displacement and strain fields. A theoretical analysis, considering the different materials was also performed for the analysis of buckling, which occurred during the compressive tests. Furthermore, a non-linear finite element analysis, considering the different mechanical properties of the explosive welded joint, was performed and was validated by means of the experimental results, obtained by the compressive tests.

This publication is available at IOS Press through this link

Integrated design of an eco-friendly wooden passenger craft for inland navigation

Authors: C. Nasso, U. la Monaca, S. Bertagna, L. Braidotti, F. Mauro, G. Trincas, A. Marinó and V. Bucci
Abstract:

The continuous increasing attention to environmental sustainability and air pollution reduction for transport systems, requires not only to adopt new technologies and innovative solutions to limit vehicles emissions, but also to study their life-cycle. In case of inland navigation, the operation close to urban areas or in natural protected environments requires the adoption of a green propulsion. Moreover, especially for small crafts, the problem of ship disposal at the end of life is of high importance, even once plastic materials should be disposed, due to high costs and process complexities. For such a reason the design of a new generation green passenger craft requires the analysis and knowledge of multiple engineering fields, that could lead to a fast and successful design only by means of an integrated approach. In the present work, this approach will be applied to the design of a passenger craft, adopting a hybrid electric powering system and build with strip planking process for wooden ships. The description of the construction process will be here described together with the on-board electric power system. The integrated approach allowed
also to directly evaluate the vessel operative profile and asses whether the vessel could perform a Zero Emission Mode navigation.

This publication is available at IOS Press through this link

Extreme loads determination on complex slender structures

Authors: F. Mauro, L. Braidotti, U. la Monaca and R. Nabergoj
Abstract:

For the dimensioning of particular structures like stingers or generic tubular elements for offshore industry, it is usual to predict the extreme values of wave
induced loads. Both for model test and calculations, the traditionally adopted methods of analysis are based on Weibull distribution. The necessity to investigate severe sea state conditions together with the increased complexity of the structure is an evident source of non-linearities in the exciting force peaks distribution.
In the specific, the adoption of a standard Weibull approach is not indicated for
accurately predict the extreme loads. The adoption of more accurate distributions
suitable to capture peaks non-linearity will ensure to overcome or capture possible multi-modal behaviour of the considered population. These enhanced techniques can be used not only for model test results analysis, but also for results coming from preliminary hydrodynamic calculations (CFD). In the present work, two different methodologies based on Mixed Weibull and Generalised Pareto distributions will be applied to the results obtained for a stinger geometry, where Morison theory is adopted to evaluate wave loads considering shield effects between the single tubular elements.

This publication is available at IOS Press through this link

Numerical simulations of a cavitating propeller in uniform and oblique flow

Authors: M. Morgut, D. Jost, A. Skerlavaj, E. Nobile, G. Contento, R. Pigazzini, T. Puzzer and S. Martini
Abstract:

The numerical predictions of a cavitating model scale propeller working in uniform and oblique flow conditions are presented. The cavitating phenomena are numerically reproduced using a homogeneous (mixture) model where three previously calibrated mass transfer models are alternatively used to model the mass transfer rate. The turbulence effect is modelled using the Reynolds Averaged Navier Stokes (RANS) approach. The simulations are performed using an open source solver. The numerical results are compared with available experimental data. For a quantitative comparison the propeller thrust is considered, while for a qualitative comparison, snapshots of cavitation patterns are shown. The thrust values obtained with the three different mass transfer models are very close to each other, however differences in the predicted cavitation patterns are observed. Moreover, some discrepancies between the numerical results and experimental data are reported.

This publication is available at IOS Press through this link

Static and dynamic comparison of megayacht deck structure’s layouts

Authors: G. Vergassola, D. Boote and L. Ricci
Abstract:

The growing increase in length of super and megayachts has driven structural designers to adopt longitudinal layouts as a main point in the structural scantlings. By the way, the optimization of weights, strength, deformations and dynamic
behaviour has to be evaluated separately for each new unit because of the particular and unique characteristics of each vessel. For this evaluation, especially for what the dynamic behaviour of ribbed plates is concerned, the use of numerical
software based on the Finite Element Method is widely used since the early design stages in order to highlight benefits and weaknesses of a particular structural design. In this paper, two different structural layouts of megayacht decks have been
studied and tested by using a FE software: the first one has been created with longitudinal and transversal stiffeners with the same cross section. In the second layout, transversal stiffeners are smaller in dimension but with lower span. The
comparison has been carried out making reference to maximum strengths, deformations and dynamic behaviour. This work, starting from an initial lay out obtained by a CS rule approach, made it possible to converge to an optimal structural  configuration, at least for what the starting geometries are concerned.

This publication is available at IOS Press through this link

ISP Volume 65, issue 2 of 2018 contains 4 articles on various topics.
These range from the development of a Life Cycle ship Performance Assessment (LCPA) method, blending economic and environmental aspects, to numerical investigations of ship maneuvering, propeller performance and seakeeping behavior.
More extensive summaries, as well as the full articles can be found on
https://content.iospress.com/journals/international-shipbuilding-progress/65/2

Life cycle ship performance assessment (LCPA): A blended formulation between costs and environmental aspects for early design stage

Authors: P. Gualeni and M. Maggioncalda
Abstract:
The development is described of a method to compare different design solutions in the early design stage with respect to performances along the whole life-cycle frame by a single parameter: the LCPA index. This index includes the impacts of bothaspects are identified and discussed. A blended formulation between Life Cycle Cost (LCC) and Life Cycle Assessment (LCA) is developed, leading to the LCPA-index. A Ship Breakdown Structure has been developed to link ship design parameters with the calculation of KPIs. The approach has been implemented and applied to a Ro-Ro passenger ship in order to validate the LCPA tool structure and its reliability.

This publication is available at IOS Press through this link

Numerical investigation on the influence of Froude number on the maneuvering characteristics of a container ship

Authors: Rameessha, T.V. and Krishankutty, P.
Abstract:
Numerical simulations are described of captive maneuvering model tests at different forward speeds for a containership to estimate the speed effect on the hydrodynamic derivatives.
It is shown that the effect of forward speed can be significant and should be taken into account when making predictions of maneuvering behavior.

This publication is available at IOS Press through this link

Improving model scale propeller performance prediction using the k-kL-ω transition model in OpenFOAM

Authors: Gaggero, S. and Villa, D.

Abstract:

Propeller performance on full scale is usually based on results of open water tests on model scale, which is usually scaled up to full scale by some semi-empirical method. In practice these appear not always to be sufficiently accurate, especially for special geometries like high skew propellers, propellers with tip rake, ducted propellers or CLT propellers. This article describes a CFD-based approach to calculate the performance of model scale propellers in open water, taking into account transition from laminar to turbulent flow. It is validated against results of experiments with three benchmark propellers and showed substantial improvements in the accuracy of the performance prediction, compared to calculations based on fully turbulent flow.

This publication is available at IOS Press through this link

CFD, potential flow and system-based simulations of fully appended free running 5415M in calm water and in waves

Authors: Toxopeus, S., Sadat-Hosseini, H., Visonneau, M., Guilmineau, E., Yen, T.-G., Lin, W.-M., Grigoropoulos, G. and Stern, F.

Abstract:
The seakeeping ability of ships is one of the aspects that needs to be assessed during the design phase of ships. Traditionally, potential flow calculations and model tests are employed to investigate whether the ship performs according to specified criteria. In the present paper, a detailed validation study of several computational methods for ship dynamics is presented. The ability of the methods to predict motions in calm water as well as in waves is investigated. In calm water, the roll decay behavior of a fully appended self-propelled free running 5415M model is investigated first. Subsequently, forced roll motions simulated by oscillating the rudders or stabilizer fins are studied. Lastly, the paper discusses comparisons between experiments and simulations in waves with varying levels of complexity, i.e. regular head waves, regular beam waves and bi-chromatic waves. The predictions for all methods are validated with an extensive experimental data set. The paper shows that only high-fidelity CFD is able to accurately predict all the relevant physics during roll decay, forced oscillation and sailing in waves.

This publication is available at IOS Press through this link

ISP Volume 65, issue 1 of 2018 contains 4 articles on various topics. These range from an experimental analysis of the seakeeping performance of catamaran forms with bulbous bows to a multiaxial fatigue assessment of welded joints in marine structures, a hydrostatic analyses of uprighting processes of capsized and damaged ships and wind-tunnel experiments on a aerodynamic interaction between two ridid sails used for wind assisted propulsion.
Summaries of these articles are provided below. These summaries, as well as the full articles can be found on https://content.iospress.com/journals/international-shipbuilding-progress/65/1 .

Experimental analysis of the seakeeping performance of catamaran forms with bulbous bows

Authors: Abdul Ghani, Pauzi| Wilson, Philip

Abstract: This paper explores the effects of adding different forms of bulbous bows onto catamaran hulls and assesses the implications on the seakeeping performance. There has been a large body of work that assess’ the effect of wave wake wash and recently studies have been undertaken to determine the effects of bulbous bows on reducing wave wake wash. However, not much research has been published on the effects of bulbous bows on the seakeeping performance of catamarans fitted with bulbous bows. This paper presents experimental results that will allow a ship designer to understand the effects of bulbous bows on heave, pitch and added resistance in waves. In conclusion it ranks the importance of different bulbous bows on the seakeeping performance.

This publication is available at IOS Press through this link

Multiaxial fatigue assessment of welded joints in marine structures

Authors: van Lieshout, P.S.| den Besten, J.H. | Kaminski, M.L.

Abstract: Structural geometry and stochastic loads such as swell and wind seas can typically induce multiaxial stress states in welded details of marine structures. It is known that such complex time varying stress states determine the fatigue resistance of welded steel joints. Therefore, it is of importance to account for them in fatigue lifetime estimation. Over the past few decades a wide variety of design guidelines and methods have been developed for multiaxial fatigue assessment, but so far there does not exist a general hypothesis applicable to all possible load cases. This study provides an overview of the current state-of-the-art in academia and engineering practice in terms of multiaxial fatigue assessment, and is focusing on the application to welded joints in marine structures. The progress of different approaches and methods is elaborated and commented upon, taking their hypothesis and (physical) basis into consideration. The insights that are provided in this paper form a valuable foundation for future investigations and emphasize the necessity of experimental proofs and model validation.

This publication is available at IOS Press through this link

Hydrostatic analyses of uprighting processes of a capsized and damaged ship

Authors: Pan, Dewei | Lin, Chengxin | Zhou, Zhaoxin | Sun, Yuqiang | Sun, Yuhao | Liu, Zhijie

Abstract: In the process of marine salvage, the capsized ship is normally required to go through a process of righting firstly, which essentially means bringing the deck to point upwards. Calculation of the righting force is the key to achieving success in designing schemes. At present, the righting force calculation relies on the use of empirical formulae. However, their accuracy and reliability is not high. In this paper, a mathematical model of the flooding quantity and righting force was established based on the hydrostatic theory applied to the ship. A three-dimensional ship model was built via General Hydrostatics software (GHS) to simulate the uprighting process of a capsized and damaged ship. Four typical uprighting processes concerning capsized ships were simulated, namely the case where about 50% of the superstructure volume was filled with water (Case 1), where about 50% of the engine room volume was filled with water (Case 2), where the superstructure was detached (Case 3) and where a large amount of air in the damaged compartments existed (Case 4). Simulation results show that the proportion between the maximum righting moment and the maximum righting moment in the opposite direction is 0.459, 0.486, 0.424 and 0.346 for cases A, B, C and D, respectively. So a larger righting force moment in the opposite direction is needed to prevent the ship from being damaged again or from capsizing again. The shear force is not always increasing with the flooding quantity or displacement. The effect of flooding water distribution is more obvious than the flooding quantity and displacement for a ship with many damaged compartments when the trim angle variation is very small. Thus, the righting force can be efficiently reduced by designing reasonable uprighting schemes.

This publication is available at IOS Press through this link

Wind-tunnel experiments on the aerodynamic interaction between two rigid sails used for wind-assisted propulsion

Authors: Bordogna, G. | Keuning, J.A.| Huijsmans, R.H.M. | Belloli, M.

Abstract: Wind-assisted propulsion has recently attracted attention as one viable option to drastically reduce pollutant emissions produced by ships. Despite its potential, there is still a substantial lack of understanding of the physical aspects proper of wind-assisted ships, leading to unreliable fuel-saving claims. In the context of the development of a performance prediction program for such type of hybrid ships, the research presented herewith deals with the aerodynamic interaction between two rigid sails. Wind-tunnel experiments were carried out on a single sail and on a two-sail arrangement, during which force and pressure measurements were taken on each sail. For the two-sail arrangement, two gap distances between the sails were investigated and the tests were performed at apparent wind angles ranging all typical sailing conditions. The results show that for an extended interval of moderate apparent wind angles the aerodynamic interaction has a positive effect on both sails. On the contrary, at smaller and at larger angles the interaction effects are detrimental for the downstream sail. The outcome of the present work indicates that the number of sails employed and their gap distance are important parameters to determine the aerodynamic interaction effects.

This publication is available at IOS Press through this link

ISP Volume 64, issue 1-2 of 2017 contains 6 articles on various topics. These range from applying RANS CFD methods to predict ship propulsive performance, to application of laminated glass in the yacht industry, ship stability during launching when applying pneumatic airbags, sloshing in LNG tanks and mitigation of bubble sweep down from a ship’s bow. Brief summaries of these articles are provided below. More extensive summaries, as well as the full articles can be found on https://content.iospress.com/journals/international-shipbuilding-progress/64/1-2.

Three-dimensional RANS method to numerically solve ship’s wave-making resistance compared with the Rankine source method

This article describes the application of a three-dimensional RANS CFD method to calculate the wave-making resistance of a Wigley hull and a Series 60 hull. The results are compared to results of calculations by a Rankine source boundary element method and results of model tests.

The here shown Illustration is reprinted from ISP, Vol number 64, Jun-ming Hu, Tie-li Li, Yan Lin, Guan Guan and Zhuo-shang Ji, Three-dimensional RANS method to numerically solve ship’s wave-making resistance compared with the Rankine source method, Pages No. 1-23, Copyright (2017), with permission from IOS Press.

 This publication is available at IOS Press through this link.

On the damping coefficient of laminated glass for yacht industry

Very large glass surfaces, that are more and more applied on yachts, are critical elements as regards the assessment of the ship’s noise and vibration characteristics. This makes the laminated glass dynamic characterization a fundamental issue to be investigated. The article describes different experimental modal methods to obtain the damping coefficient at natural frequencies, applied to laminated glass specimens. The results of these methods are compared with each other.

The shown Illustration is reprinted from ISP, Vol number 64, D. Boote, T. Pais, G. Vergassola, A. Tonelli and L. Gragnani, On the damping coefficient of laminated glass for yacht industry, Pages No. 25-40, Copyright (2017), with permission from IOS Press.

This publication is available at IOS Press via this link

Ship stability analysis during launching from longitudinal sloping slipway by pneumatic airbags

This article presents a new analysis method of taking into account the possibility of a tanker tipping during launching on pneumatic airbags. Launching calculations and diagrams for both the traditional and pneumatic airbags launching are presented along with a comparative analysis of the two launching methods.

This publication is available at IOS Press via this link

Prediction of ship power and speed performance based on RANS method

This article describes the application of CFD RANS methods to calculate the open water performance of a ducted propeller model for a fishing vessel, the resistance of the model of this vessel and the propulsive performance of this ship model when fitted with the subject propeller model. The results are compared with results of model tests.

The Illustration is reprinted from ISP, Vol number 64, Jun-ming Hu, Tie-li Li, Yan Lin, Guan Guan and Zi-bo Zheng, Prediction of ship power and speed performance based on RANS method, Pages No. 51-78, Copyright (2017), with permission from IOS Press.

This publication is available at IOS Press via this link.

A numerical technique for sloshing in an independent type C LNG tank with experimental investigation and validation

Sloshing induced by partial loading is violent when a resonance condition occurs. Given strong nonlinearity, rapid and accurate prediction of sloshing loads under resonance conditions is the key factor in the design of LNG cargo tanks.
This article describes the application of a CFD technique to simulate sloshing, and experiments conducted to verify the results of the simulations. The results of both approaches are compared to each other.

This Illustration is reprinted from ISP, Vol number 64, Ge Liu, Yan Lin, Guan Guan and Yan-yun Yu, A numerical technique for sloshing in an independent type C LNG tank with experimental investigation and validation, Pages No. 79-100, Copyright (2017), with permission from IOS Press.

This publication is available at IOS Press via this link

Dydrodynamic design for mitigation of bubble sweep down in sonar mounted research vessels

Oceanographic research vessels are fitted with acoustic sonar transducers at the bottom keel region.
Bubbles that are swept down from the bow region interfere with the acoustic transmission and deteriorate the functioning of the sonar transducer. This article describes the development of a special bow shape, due to which the path of swept down bubbles is diverted away from the acoustic sonar transducer. This development includes the application of RANS CFD and experiments on model scale..

This Illustration is reprinted from ISP, Vol number 64, M. Palaniappan and V. Anantha Subramanian, Hydrodynamic design for mitigation of bubble sweep down in sonar mounted research vessels, Pages No. 101-126, Copyright (2017), with permission from IOS Press.

This publication is available at IOS Press via this link

On this page, you will find short summaries of the articles included in the relevant editions of ISP Journal, per year and quarterly edition.
With each article you will find a link to the IOS press website, where you can read more about that article and the relevant edition and how to order it.

Back to the ISP Journal introduction page.

ISP Volume 63, numbers 3,4 of 2016/2017 is a special issue about the European Union (EU) project GRIP. GRIP stands for “Green Retrofitting through optimization of hull-Propulsion Interaction”. The project addressed several aspects of fitting Energy Saving Devices (ESD’S) to existing ships.

Aspects that were addressed are among others: the working principles of ESD’s, the development of an Early Assessment Tool (EAT) to estimate the energy saving potential of a specific ESD to a specific ship, structural aspects (loads, fatigue and vibrations), and the shipyard process to fit an ESD to a ship of which the hull geometry is not exactly known. Within the project a specific ESD has been designed, built and tested on full scale.

This ISP issue contains 9 articles, covering all aspects from estimating the power saving potential to the actual design and construction of ESD’s, fitting them to a ship and testing tem on full scale.

Summaries, as well as the complete contents of the articles included in ISP Volume 63, numbers 3,4 can be found via the IOS Press website via this link 

Back to the ISP Journal introduction page.