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  • 1.
    Alexandersson, Martin
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Kjellberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Mao, W.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas W
    Chalmers University of Technology, Sweden.
    Prediction of roll motion using fully nonlinear potential flow and ikeda’s method2021In: Proceedings of the International Offshore and Polar Engineering Conference, International Society of Offshore and Polar Engineers , 2021, p. 1670-1679Conference paper (Refereed)
    Abstract [en]

    Getting the best possible accuracy with the lowest possible computational cost is an important factor in the early design stage of ships. Potential flow-based analysis presents such a solution for seakeeping analyses. The accuracy of roll motion in potential flow is however not so good, due to the large influence from vicsous roll damping, which is missing in these calculations. This paper proposes a hybrid method, as a solution to this problem, where the viscous roll damping from Ikeda’s semi-empirical method is injected into an existing 3D unsteady fully nonlinear potential flow (FNPF) method. The hybrid method is investigated using roll decay tests with the KVLCC2 test case. This investigation shows that the accuracy of simulated roll motions is significantly improved and also shows good agreement with the corresponding roll decay model tests.

  • 2.
    Alexandersson, Martin
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Mao, Wengang
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas W
    Chalmers University of Technology, Sweden.
    Analysis of roll damping model scale data2021In: Ships and Offshore Structures, ISSN 1744-5302, E-ISSN 1754-212X, Vol. 16, no S1, p. 85-92Article in journal (Refereed)
    Abstract [en]

    Having an accurate prediction of ship roll damping is crucial when analysing roll motions. In this paper, the simplified Ikeda method (SI-method) is compared with the original Ikeda method. The methods are compared using results from a database of roll decay tests carried out on modern merchant ships and a smaller set of predictions in which the original Ikeda method was used. It was found that most of the ships in the database had dimensions outside the limits of the SI-method. Thus, the SI-method showed poor agreement with model tests outside its limits but acceptable agreement for ships within limits. It was found that the deviations were caused by extrapolation errors of the wave-damping in the SI-method. Two ways to improve the accuracy of the SI-method were proposed based on regression, which gave about the same accuracy as the original Ikeda method. © 2021 The Author(s).

  • 3.
    Alexandersson, Martin
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Mao, Wengang
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas W
    Chalmers University of Technology, Sweden.
    System identification of Vessel Manoeuvring Models2022In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 266, article id 112940Article in journal (Refereed)
    Abstract [en]

    Identifying the ship's maneuvering dynamics can build models for ship maneuverability predictions with a wide range of useful applications. A majority of the publications in this field are based on simulated data. In this paper model test data is used. The identification process can be decomposed into finding a suitable manoeuvring model for the hydrodynamic forces and to correctly handle errors from the measurement noise. A parameter estimation is proposed to identify the hydrodynamic derivatives. The most suitable manoeuvring model is found using the parameter estimation with cross-validation on a set of competing manoeuvring models. The parameter estimation uses inverse dynamics regression and Extended Kalman filter (EKF) with a Rauch Tung Striebel (RTS) smoother. Two case study vessels, wPCC and KVLCC2, with very different maneuverability characteristics are used to demonstrate and validate the proposed method. Turning circle predictions with the robust manoeuvring models, trained on zigzag model tests, show good agreement with the corresponding model test results for both ships. © 2022 The Author(s)

  • 4.
    Alexandersson, Martin
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Zhang, Daiyong
    Chalmers University of Technology, Sweden.
    Mao, Wengang
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas W
    Chalmers University of Technology, Sweden.
    A comparison of ship manoeuvrability models to approximate ship navigation trajectories2023In: Ships and Offshore Structures, ISSN 1744-5302, E-ISSN 1754-212X, Vol. 18, no 4, p. 550-557Article in journal (Refereed)
    Abstract [en]

    It is essential to describe a ship’s manoeuvrability for various applications, e.g. optimal control of unmanned surface vehicles (USVs). In this study, the capability of two recognised manoeuvrability models to predict ships’ trajectories is investigated based on both simulation and open-water experiment test data. The parameters of these models are estimated by a statistical learning method. The goodness of the two estimated models for describing a merchant ship’s manoeuvrability is first studied using her manoeuvring simulation data. Then, experimental manoeuvring tests to use a USV in open water with wind and drifting effects are used to check the conventional model identification procedures. Finally, some modifications and adjustments are proposed to improve the conventional procedures. It shows that the proposed procedures can accurately derive the ship’s manoeuvrability based on experimental data. © 2022 The Author(s). 

  • 5.
    Andersson, Jennie
    et al.
    Chalmers University of Technology, Sweden.
    Shiri, Alex
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Yixing, Jin
    China Ship Scientific Research Center, China.
    Chengsheng, Wu
    China Ship Scientific Research Center, China.
    Gengyao, Qiu
    China Ship Scientific Research Center, China.
    Deng, Ganbo
    Ecole Centrale de Nantes, France.
    Queutey, Patrick
    Ecole Centrale de Nantes, France.
    Xing-Kaeding, Yan
    Hamburg Ship Model Basin, Germany.
    Horn, Peter
    Hamburg Ship Model Basin, Germany.
    Lücke, Thomas
    Hamburg Ship Model Basin, Germany.
    Kobayashi, Hiroshi
    National Maritime Research Institute, Japan.
    Ohashi, Kunihide
    National Maritime Research Institute, Japan.
    Sakamoto, Nobuaki
    National Maritime Research Institute, Japan.
    Yang, Fan
    Shanghai Ship and Shipping Research Institute, Chia.
    Gao, Yuling
    Shanghai Ship and Shipping Research Institute, China.
    Windén, Björn
    SHORTCUt CFD, USA.
    Meyerson, Max
    University of Michigan, USA.
    Maki, Kevin
    University of Michigan, USA.
    Turnock, Stephen
    University of Southampton, UK.
    Hudson, Dominic
    University of Southampton, UK.
    Banks, Joseph
    University of Southampton, UK.
    Terziev, Momchil
    University of Strathclyde, UK.
    Tezdogan, Tahsin
    University of Strathclyde, UK.
    Vesting, Florian
    Volupe AB, Sweden.
    Hino, Takanori
    Yokohama National University, Japan.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Ship-scale CFD benchmark study of a pre-swirl duct on KVLCC22022In: Applied Ocean Research, ISSN 0141-1187, E-ISSN 1879-1549, Vol. 123, article id 103134Article in journal (Refereed)
    Abstract [en]

    Installing an energy saving device such as a pre-swirl duct (PSD) is a major investment for a ship owner and prior to an order a reliable prediction of the energy savings is required. Currently there is no standard for how such a prediction is to be carried out, possible alternatives are both model-scale tests in towing tanks with associated scaling procedures, as well as methods based on computational fluid dynamics (CFD). This paper summarizes a CFD benchmark study comparing industrial state-of-the-art ship-scale CFD predictions of the power reduction through installation of a PSD, where the objective was to both obtain an indication on the reliability in this kind of prediction and to gain insight into how the computational procedure affects the results. It is a blind study, the KVLCC2, which the PSD is mounted on, has never been built and hence there is no ship-scale data available. The 10 participants conducted in total 22 different predictions of the power reduction with respect to a baseline case without PSD. The predicted power reductions are both positive and negative, on average 0.4%, with a standard deviation of 1.6%-units, when not considering two predictions based on model-scale CFD and two outliers associated with large uncertainties in the results. Among the variations present in computational procedure, two were found to significantly influence the predictions. First, a geometrically resolved propeller model applying sliding mesh interfaces is in average predicting a higher power reduction with the PSD compared to simplified propeller models. The second factor with notable influence on the power reduction prediction is the wake field prediction, which, besides numerical configuration, is affected by how hull roughness is considered. © 2022 The Authors

  • 6.
    Awais, Fawad
    et al.
    University of Gothenburg, Sweden.
    Flodén, Jonas
    University of Gothenburg, Sweden.
    Svanberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Logistic characteristics and requirements of Swedish wood biofuel heating plants2021In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 138, article id 110650Article in journal (Refereed)
    Abstract [en]

    The demand for wood biofuel for district heating plants and combined heat and power plants (CHPs) has increased, caused by an increase in both the number and size of CHPs. This places large demands on the logistics system supplying these plants with fuel, with a particular interest in the use of alternative modes of transport such as rail and sea. The aim of this paper is to identify the industry actors’ requirements, constraints, and preferences regarding the wood-biofuel supply chain and to identify the logistical challenges this entails, as well as how this impacts the opportunity for an increased use of alternative transport solutions. A survey was sent to all Swedish CHPs, combined with six interviews with transport companies, terminal operators, and forest companies. The study shows that the industry has a local focus that limits potential logistics and sourcing solutions. It is also challenged by urban sprawl, with expanding residential areas close to the CHPs putting further constraints on the operations. Significant variations in fuel demand, depending on unpredictable outside temperature and seasonal variation, is a further challenge. The low density of the fuel has a negative impact on transport costs and introduces a trade-off between chipping close to the forest to increase density versus more efficient chipping at the CHP. Intermodal transport only used by large plants, driven by a shortage of local fuel. © 2020 The Authors

  • 7.
    Bach, Andreas
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Forsström, Ellinor
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Haraldson, Sandra
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Holmgren, Kristina
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Lind, Kenneth
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Lind, Mikael
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Piehl, Hampus
    RISE Research Institutes of Sweden, Safety and Transport, Electrification and Reliability.
    Raza, Zeeshan
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Rydbergh, Torbjörn
    Marine Benchmark, Sweden.
    HAMNEN SOM ENERGINOD : Ett koncept för hamnens roll i omställningen mot ett hållbart transportsystem2022Report (Other academic)
    Abstract [sv]

    Transportsystemet står inför en enorm utmaning då trycket på genomförandet av hållbara operationer aldrig varit större. Enligt IEA står transportsektorn för 16% av det totala koldioxidutsläppet i världen som med nödvändighet måste minska för att vi ska kunna lämna efter oss en planet med resurser för framtida generationer. Utmaningen kräver att alla delar av transportsystemet gör sitt bidrag, oavsett om det handlar om transportoperatörer, transportnoder, myndigheter på såväl lokal, regional som global nivå och tvärs samtliga transportslag. Det slutar dock inte där, det är lika viktigt att de som konstruerar olika typer av lastbärare och fordon för både gods- och persontransporter också beaktar den energi som förväntas vara tillgänglig i rätt kvantitet och till rätt pris. Energiproducenter behöver också tillgodose att efterfrågade energibärare produceras och finns att tillgå vid rätt plats och i tillräcklig kvantitet då den behövs. Detta är i linje med de behov av insatser som Sveriges regering lyfter inom transporteffektivitet, hållbara förnybara drivmedel samt energieffektiva fordon och fartyg, för att reducera Sveriges territoriella CO2 utsläpp i linje med de globala målen. En viktig del av transportsystemet är hamnar som har fönster mot flera olika transportslag och utgör multimodala noder som förväntas ombesörja en så sömlös övergång mellan olika transportslag som möjligt, såsom till/från sjö, järnväg och väg. Svenska hamnar är inget undantag, utan i Sverige med sin längsta europeiska kustremsa behöver Sveriges hamnar också etablera tillräcklig kapabilitet för att hantera såväl inhemska transportbehov som förväntade transporter för import och export på ett hållbart sätt. Hamnar står inför utmaningen att både bedriva sina operationer på ett så hållbart sätt som möjligt genom nyttjande av fossilfri energi, att förse besökare med fossilfria energibärare, och att balansera sitt nyttjande och distribution av hållbar energi med de behov som omgivningen har. Organisationer med lastbilar, tåg, och fartyg som besöker en transportnod, däribland hamnar, förväntar sig att de kan försörjas med viss energi. Transportnoder kan således inte bara betraktas utifrån att vara en effektiv omlastningspunkt, utan behöver också betraktas utifrån den roll som transportnoden har och kan komma att ta i den del av energisystemet som relaterar till transportsystemet. Hamnar som transportnoder behöver således etablera en förmåga som energinod. I föreliggande projekt har trender beaktats för utvecklingen inom olika transportslag, intervjuer genomförts med svenska hamnar samt en enkätundersökning genomförts riktad till en majoritet av Sveriges hamnar. I projektet identifieras att de viktigaste drivkrafterna för hamnarnas hållbarhets- och omställningsarbete är kundkrav, kostnadsbesparingar, hamnens interna målsättning (ofta baserad på ägarnas krav och vision) samt regelverk. Slutsatsen är att Sveriges hamnar har en stark ambition att utveckla sin förmåga som energinod för olika roller. Samtidigt råder en villrådighet om vilka satsningar som skulle ge störst effekter för hamnens verksamhet. Viktigt att notera är också att olika hamnar har olika förutsättningar och roller i transportsystemet, beroende på dess geografiska placering, storlek och typ av gods / passagerare som hanteras. Samtidigt görs stora investeringar i Sveriges hamnsystem, för att proaktivt utveckla en kapabilitet att möta dagens och morgondagens transportbehov, särskilt i ljuset av den omflyttning som sker från vägbundna transporter till järnväg och sjö. Det är vanligt att hamnar etablerar inlandsterminalskapabilitet, d v s skapar förmåga för omlastning mellan tåg och väg där inte någon sjötransport behöver vara inblandad. Många av Sveriges järnvägsoperatörer ser hamnar som strategiska noder i järnvägssystemet. Dessutom det är tydligt från intervjuerna, vilket även styrks av enkätsvar, att respondenterna anser att otillräckliga finansiella medel, höga kostnader och skatt, omogen teknik, infrastruktur, effekt, standardisering, kompetens, och politisk otydlighet är de största utmaningar som påverkar svenska hamnars roll i hållbarhets- och omställningsarbete. Baserat på genomförd trend- och nulägesanalys föreslås en mognadsmodell som rådgivande för hamnens proaktiva utveckling av sin energinodskapacitet. Denna modell tar utgångspunkt i att hamnen etablerar en energistrategi som tar höjd för nödvändiga samarbeten och investeringar som de både blir tvingade till genom regelverk, påverkade av genom beslut och själva har rådighet över. Hamnarna är tydliga med att huvudverksamheten är att utgöra en transportnod, men att de, för att möjliggöra en omställning mot ett hållbart transportsystem, också behöver ge utrymme för andra aktörer, såsom energiproducenter och energidistributörer att bedriva sin verksamhet relaterat till hamnens geografiska område. Således behöver det kluster av aktörer som ingår i hamnen som nod expanderas till att också innefatta producenter och distributörer av energi. Hamnens energistrategi är rådgivande för att hamnen skall kunna etablera en förmåga som säkerställer att de krav som hamnens operationer, hamnens besökare och hamnens roll med sin geografiska placering, möts. Föreslagen mognadsmodell riktar uppmärksamhet just till dessa nivåer av förmåga och skapar grunder för formuleringen av en proaktiv strategi för den enskilda hamnens roll i transportsystemets energiomställning. En viktig grund blir då att simulera framtida energibehov, såsom inom elförsörjnings- och eldistributionsområdet, men även för andra energibärare, varför detta projekt föreslår ett fortsättningsprojekt där förväntade energibehov kan simuleras och bli rådgivande för strategi, samverkan och investering för Sveriges hamnar. En sådan simuleringsmodell bygger på hamnens digitala förmåga att fånga och använda data från operationer för att säkerställa att hamnen bidrar till transporteffektivitet, användning av hållbara förnybara drivmedel samt energieffektiva fordon och fartyg. Samspelet mellan hamnen som energinod och transportbärares kapabilitet att drivas på hållbar energi samt energiproducenters/energidistributörers förmåga att tillhandahålla fossilfri energi, utgör grunden till fossilfria transporter. Fossilfria väg-, järnvägs- och sjötransporter kan således inte etableras utan att ta hänsyn till alla ingående komponenter. I denna nödvändiga transformation har hamnar och andra transportnoder en nyckelroll.

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  • 8.
    Burden, Håkan
    et al.
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Stenberg, Susanne
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Carlgren, Lisa
    RISE Research Institutes of Sweden, Digital Systems, Prototyping Society.
    Sjöblom, Ted
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Policylabb Smarta Fartyg2022Report (Other academic)
    Abstract [en]

    Swedish Shipping Policy Lab

    Smart ships, or Maritime Autonomous Surface Ships as they are also known, have a great potential to advance shipping and sustainable development through optimisation of operations and maintenance. In situations that pose a risk to humans or where humans tend to lose their concentration, smart ships can also contribute to increased safety onboard and for the environment. In short, smart ships are suitable for operations that are dirty, dull and dangerous. The Swedish Shipping Policy Lab was an initiative to support on-going projects within smart shipping with policy-developing activities with the ambition to strengthen Swedish competitiveness. The project has actively strived for a systematic approach to how shipowners, technology developers and authorities among others can foster policy development and innovation in relation to smart ships. As an outcome the project has identified three policies related to the investigated cases (see Appendix G for more details): 1. Navigational assistance from land – A shared statement by the Swedish Maritime Administration and the Swedish Transport Agency on the role of navigational assistance from land and the need to further investigate the service before it can be regulated in more detail. 2. The Ljusterö Ferry – Certification of ferries is commonly done in relation to an established and consistent set of technical requirements. For smart ships such as the new road ferries procured for the Ljusterö-connection it is reasonable to complement traditional certification with a safety case to ensure that the ship is seaworthy. 3. Smart maritime drones – Ships less than five meters long that do not carry passengers are excluded from national rules regulating the supervision performed by the Swedish Transport Agency. As long as there is no explicit need to inspect a specific ship, the probability of a supervision is low. If an inspection were to incur, it is necessary to show how the smart ship and its operation complies to applicable regulation in terms of laws and collision avoidance. Despite the maritime sector having a long tradition of international governance there are still no international instruments explicitly for smart ships. A conclusion from the policy lab is that while such work is ongoing, there is room for the flag states and their authorities to develop and operate smart ships in accordance with national policies. Or, to paraphrase, smart ships seem suitable for operations that are dirty, dull, dangerous and domestic.

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  • 9.
    Burden, Håkan
    et al.
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Stenberg, Susanne
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Carlgren, Lisa
    RISE Research Institutes of Sweden, Digital Systems, Prototyping Society.
    Sjöblom, Ted
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    The Swedish policy lab for maritime autonomous surface ships2022Conference paper (Refereed)
    Abstract [en]

    The Swedish policy lab for maritime autonomous surface ships, or smart ships, explored three use cases for developing policy in practice. The policies regard smart ships on national waters: one short-term written policy identifying the next shared step for two authorities to position remote navigational assistance as a new service, giving the maritime ecosystem one official position to relate to; one informal policy relying on a mutual trust, where information sharing between an operator of small, unmanned ships and the supervisory authority enables critical competence building; and one evolving policy on the process of certifying autonomous or remote operated functions using non-standardized technology. In conclusion, despite shipping being explicitly regulated internationally we found that there is substantial leeway for national policies regarding smart ships on national waters.

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  • 10.
    Carlsson, Annika
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Electrification and Reliability.
    Fast, Lars
    RISE Research Institutes of Sweden, Safety and Transport, Electrification and Reliability.
    Nordin Fürdös, Axel
    RISE Research Institutes of Sweden, Safety and Transport, Electrification and Reliability.
    Adams, Paul
    RISE Research Institutes of Sweden, Safety and Transport, Electrification and Reliability.
    Forsström, Ellinor
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Haberl, Felix
    Volvo, Sweden.
    Johansson, Monica
    Volvo, Sweden.
    Parthav, Desai
    Volvo, Sweden.
    Flytande väte som ett logistiskt bränsle – En förstudie2022Report (Other academic)
    Abstract [en]

    Large investments are being made by energy companies to provide hydrogen production, distribution, and refuelling infrastructure. It is hence critical to find hydrogen pathways that are efficient and feasible. This means deciding between the usage of liquid hydrogen (LH2) or compressed hydrogen (CGH2) value-chains from production to storage onboard vehicles in some transport segments such as heavy-duty trucks. During the project the as yet unestablished concept of cryo-compressed hydrogen (CcH2) was also considered. The project aimed at identifying the critical challenges and current limitations that impact the widespread use of hydrogen as a fuel for transport applications. It has focused on increasing the knowledge about technologies that can make LH2 or CGH2 infrastructure and vehicle usage more efficient and safer, by assessing the current state of technology as well as maturity and potential of new technologies. Included in this was also a segment focused on the safety of the different alternatives along the later parts of the value-chain. The project as a whole was conducted as a literature study. For the technology maturity in different parts of the value-chain the project has summarized the results in a very high-level categorisation system, see table below The definitions are mainly qualitatively and show where the technologies are in these categories: • Established (Used on a larger scale, ~TRL 9-10) • Proven concept (Demonstrators or soon reaching this stage, ~TRL 7-8) • Initial design (No public demonstrators available, ~TRL 3-6) • Uncertain applicability (Applicability was not established in this work) • Not applicable (Cannot be used for this state of hydrogen) Technological maturity in the hydrogen value-chain The table above also gives an overview of the segments included in the report. In combination with the technological evaluation a qualitative cost analysis of the different hydrogen storage states was also done. Here it is indicated that though LH2 has a higher cost in the initial part of the value-chain, it has lower costs in the end segments. Therefore, it is possible that the end-price for the user will be similar for both LH2 and CGH2. The full cost can be compared first when LH2 refuelling stations and vehicles are publicly built, and cost information is available. The same is true for CcH2. During the safety, regulations and standards pre-study the following was concluded. From a safety perspective, there are no insurmountable barriers with respect to the use of LH2 on-board heavy-duty road vehicles in the medium term, however, there are several challenges to overcome, not least in the short term. Within the EU there are regulations which allow the type-approval of heavy-duty road vehicles with LH2 storage systems. However, these are based on work undertaken 15 - 20 years ago and are widely acknowledged as in need of being updated and validated in the same way that CGH2 road vehicle regulations have been. Similarly, there is a lack of up-to-date industry standards for road vehicle LH2 storage systems. A particular gap is the absence of an up-to-date standard that can be referenced in regulations for the refuelling receptacle geometry. Additionally, for LH2 refilling stations as a whole there are no suitable, up to date international standards, so there is a risk that individual countries set their own requirements. Overall, the project concluded that there are no show-stoppers for the implementation of LH2. It is a feasible value-chain from both the technology, cost and safety perspective. It could also in the future become comparable with the more proven CGH2 value-chain, but some initial hurdles and investments need to be overcome.

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  • 11.
    Castrellon, Juan Pablo
    et al.
    Chalmers University of Technology, Sweden; Universidad Nacional de Colombia, Colombia.
    Sanchez-Diaz, Ivan
    Chalmers University of Technology, Sweden.
    Roso, Violeta
    Chalmers University of Technology, Sweden.
    Altuntas-Vural, Ceren
    Chalmers University of Technology, Sweden.
    Rogerson, Sara
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Santén, Vendela
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Kalahasthi, L. K.
    Chalmers University of Technology, Sweden.
    Assessing the eco-efficiency benefits of empty container repositioning strategies via dry ports2023In: Transportation Research Part D: Transport and Environment, ISSN 1361-9209, E-ISSN 1879-2340, Vol. 120, article id 103778Article in journal (Refereed)
    Abstract [en]

    Trade imbalances and global disturbances generate mismatches in the supply and demand of empty containers (ECs) that elevate the need for empty container repositioning (ECR). This research investigated dry ports as a potential means to minimize EC movements, and thus reduce costs and emissions. We assessed the environmental and economic effects of two ECR strategies via dry ports—street turns and extended free temporary storage—considering different scenarios of collaboration between shipping lines with different levels of container substitution. A multi-paradigm simulation combined agent-based and discrete-event modelling to represent flows and estimate kilometers travelled, CO2 emissions, and costs resulting from combinations of ECR strategies and scenarios. Full ownership container substitution combined with extended free temporary storage at the dry port (FTDP) most improved ECR metrics, despite implementation challenges. Our results may be instrumental in increasing shipping lines’ collaboration while reducing environmental impacts in up to 32 % of the inland ECR emissions. © 2023 The Author(s)

  • 12.
    Coslovich, Franciesco
    et al.
    Chalmers University of Technology, Sweden.
    Kjellberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Östberg, Magnus
    Flowtech International AB, Sweden.
    Janson, Carl-Erik
    Chalmers University of Technology, Sweden.
    Added resistance, heave and pitch for the KVLCC2 tanker using a fully nonlinear unsteady potential flow boundary element method2021In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 229, article id 108935Article in journal (Refereed)
    Abstract [en]

    In this paper, a fully nonlinear unsteady potential flow method is used to predict added resistance, heave and pitch for the KVLCC2 hull in regular head waves at design speed. The method presents a nonlinear decomposition of the velocity potential and the wave field and an adaptive grid refinement. A formulation for the acceleration potential is used to obtain the pressure. To improve computational efficiency, a Barnes-Hut algorithm is introduced. A grid dependency study and a study on the impact of different time steps on the solution are performed. Numerical results have been compared with experimental data for the design speed. A general good agreement is found for added resistance, especially for longer waves. Heave and pitch are properly computed for all wave lengths in the range λ/Lpp=0.4 to 1.4. © 2021 The Author(s)

  • 13.
    Dahlbom, Sixten
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Sanfridson, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Sjöblom, Ted
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Evaluation of Detection Principles and Challenges in Early Detection of Thermal Runaway in Batteries2023Report (Other academic)
    Abstract [en]

    The amount of battery electrical vehicles (BEVs) carried as cargo on ro-ro ships is increasing. The possibility of thermal runaway in a lithium-ion battery makes BEVs a different fire risk compared to internal combustion engine vehicles (ICEV). One of the challenges that arise is how to detect a thermal runaway early. Current detection systems in ro-ro spaces generally consist of smoke and/or heat detection. To identify potential techniques and challenges for detection of a thermal runaway, as early as possible, tests with batteries and detectors are needed. Tests with one battery cell were performed inside an ISO container (with almost negligible ventilation) as well as in an open room with moderate ventilation (14 air changes per hour). Point-type detectors (two smoke and heat detectors, one CO detector, and one LEL detector), thermal imaging, video analytics, and light detection and ranging (LIDAR) were evaluated in the tests. A total of 14 tests were conducted. The detectors were evaluated in different positions relative to the battery cell and comparative tests with wood-sticks were performed to investigate the detectors’ ability to detect a more conventional source of fire. Based on the results, it can be concluded that early detection of thermal runaway in batteries is possible in principle. However, detection is a matter of circumstances e.g., ventilation, gas/smoke production and the location of the detector(s). The result indicates that detection in a small and confined space is relatively manageable, but detection in a large and open space could be more of a challenge. If the gas/smoke is cooled down it may sink and spread along the floor/deck, instead of rising and spreading along the ceiling. This would be a challenge with current smoke detectors installed in the ceiling. Shielding may be a problem, especially with LIDAR and thermal imaging. Future research should address full-scale tests, and it is recommended to include Optical Gas Imaging (OGI) as a mean of detection.

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  • 14.
    Dixit, Saubhagya
    et al.
    Scientist Central Pollution Control Board, India.
    Rao, K Ramachandra
    Indian Institute of Technology, India.
    Tiwari, Geetam
    Indian Institute of Technology, India.
    von Wieding, Sönke
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Urban freight characteristics and externalities – A comparative study of Gothenburg (Sweden) and Delhi (India)2022In: Journal of Transport and Supply Chain Management, ISSN 2310-8789, E-ISSN 1995-5235, Vol. 16, article id a629Article in journal (Refereed)
    Abstract [en]

    Background: The urban freight transportation (UFT) system is an essential facilitator for the smooth functioning of city logistics. It also contributes significantly to transportation-related issues, such as vehicular congestion, pollution, accidents, infrastructure damage and other related problems. Objectives: This study aimed to understand and compare the urban freight traffic characteristics and their impact in two cities: Gothenburg, Sweden and Delhi, India, having high socio-economic differences. The findings of this study will be helpful for practitioners and policymakers in the development and successful implementation of UFT management policies. Method: Using the cordon count (traffic data), retailers’ interviews (receivers’ data) and freight vehicle drivers’ interviews, UFT characteristics such as sector-specific contribution, trip characteristics, vehicular characteristics and negative impacts in terms of external cost to society are evaluated. This study also discusses the prediction of attracted trips in the study zone using freight trip attraction (models. Results: About 75% of the trips in Gothenburg and 92% of the trips in Delhi are made by light commercial and other small-sized vehicles. Gothenburg has formally organised sectors involved in freight vehicle movement; however, Delhi has informally organised sectors. Conclusion: The results revealed substantial differences in characteristics of freight trip operations in both the cities, compared with few similarities. Measures taken considering the specific local attributes of freight traffic and stakeholders’ requirement may lead to a sustainable transportation system in cities. © 2022. The Authors.

  • 15.
    Eriksson, Anna
    et al.
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    von Wieding, Sönke
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Gestrelius, Sara
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Lyrberg, Magnus
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Ranäng, Sara
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Carlén, Vanja
    Closer, Sweden.
    Hansson, Marcus
    Closer, Sweden.
    REDIG- Regionala godshubbar i Göteborg: FÖRSTUDIE – DRIVE SWEDEN2023Report (Other academic)
    Abstract [sv]

    Denna rapport är ett resultat av en förstudie kring en logistik- och transportlösning (som kan realiseras i form av en gemensam hubb) för aktörer som är placerade i evenemangsstråket i Göteborg. Rapporten svarar på frågor kring nulägesanalys av aktörernas logistiklösningar, leveranstrafik inom evenemangsstråket, samt hur leveranstrafik kan se ut under 2030+ om inga förändringar i leverans/logistikupplägget görs. En viktig slutsats som framgår är att det krävs åtgärder som minskar leveranstrafiken, eftersom elektrifiering av fordon inte kan eliminera trängsel och buller som står för den största delen av de samhällsekonomiska kostnaderna. Utan förändringar i logistikupplägget och fordonsflottan förväntas de samhällsekonomiska kostnaderna öka med cirka 30%. Förändringar i logistikupplägget kan nås genom ett optimerad trafikflöde, vilket i sin tur kan realiseras genom en gemensam samlastningshubb för små och fragmenterade flöden som kan minska antalet anlöp och fordonstrafiken i området. Baserat på intervjuer med aktörerna, studiebesök, studerande av underlag, workshops och analys av logistikbehoven, kan det sammanfattas att verksamheterna, utmaningar och logistikbehoven i stort sett är ganska lika. En gemensam extern hubb kan frigöra yta hos verksamheterna som kan användas för att skapa nya affärsmöjligheter. En möjlighet för att upphandla en tredjeparts logistik- och transportlösning är att bygga ett konsortium där alla aktörer delar på kostnaden för terminalhantering samt samlastning/samkörning. Det finns stora möjligheter att hitta lösningar för logistikhubb som uppfyller kraven på geografisk närhet och säkra leveranser i trafiksystemet – och det är klokt att anpassa leveranstider för att undvika trängsel. Det finns en vilja hos aktörerna att minska transporterna, anpassa sin verksamhet för effektivisering vid mottagning och förvaring, ställa om mot fossilfrihet och på det sättet bidra till transporteffektivitet som krävs för att nå mål inom klimatneutralitet 2030. Det finns stora behov för förändring i trafikflödet inom GGCZ och det finns en stor potential att optimera det genom att konsolidera och styra leveranser.

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  • 16.
    Eslamdoost, Arash
    et al.
    Chalmers University of Technology, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Brown, Matz
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    A device for reducing the resistance of transom stern hulls2021In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 235, article id 109351Article in journal (Refereed)
    Abstract [en]

    A novel idea to reduce the resistance of a transom stern hull in displacement and semi-planing modes is investigated. By placing a spoon-shaped device in the recirculating zone behind the transom, the momentum of the forward-moving water will be absorbed, and a pushing force generated on the device. Numerical and experimental techniques are applied on a transom stern hull to optimize the shape and position of the device and to explore in detail the physics behind the gain. For the towed hull at a Froude number of 0.4, the maximum measured resistance reduction is 11%, while the computed maximum reduction is 17%. In self-propulsion with one propeller, the measured power reduction is 15%. The power cannot be computed with the applied propeller model, which is an axial body-force distribution in the propeller disk, but the reduction in thrust using the device is 11%. More significant gains are possible at smaller Froude numbers, while the effect is reduced at higher Froude numbers. Larger gains are achieved by splitting the thrust on two propellers. © 2021 The Authors

  • 17.
    Finnsgård, Christian
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Liefvendahl, Mattias
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Ship power prediction with CFD in full scale2023Report (Other academic)
    Abstract [en]

    This report demonstrates the qualifications of RISE to carry out CFD for ship self-propulsion, thus predicting the delivered power. The procedures were fully developed at SSPA which became fully integrated into the Maritime Department of RISE by 2023-01-01. An outline is given of the best-practice guidelines used at SSPA/RISE and how they comply with the relevant ITTC recommendations for verification and analysis. In addition, an overview is given of previous validation studies performed for a wide range of ships, including comparison with both model-scale and full-scale data. Complete references are provided to reports and publications in which these SSPA studies and methods are described in detail.

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  • 18.
    Gypa, Ioli
    et al.
    Chalmers Tekniska Högskola, Sweden.
    Jansson, Marcus
    Kongsberg Maritime Sweden AB, Sweden.
    Gustafsson, Robert
    Kongsberg Maritime Sweden AB, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers Tekniska Högskola, Sweden.
    Controllable-pitch propeller design process for a wind-powered car-carrier optimising for total energy consumption2023In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 269, article id 113426Article in journal (Refereed)
    Abstract [en]

    Wind-powered ship propulsion (WPSP) is the concept where the wind is the main source of thrust, while the traditional propulsion system operates when needed. This type of propulsion can lead to considerably reduced emissions, something that the shipping community is striving for. A well-known example of WPSP is the Oceanbird with the goal to cut emissions of up to 90%. In this study, the propeller design process for a wind-powered car-carrier (wPCC) such as the Oceanbird is investigated, what the various challenges of WPSP are and therefore how an automated optimisation procedure should be approached. A controllable-pitch propeller was selected as suitable propeller type for the operation of the wPCC, and various functions such as windmilling, feathering and harvesting have been explored. Regarding the optimisation procedure, an essential input is the definition of the operational profile, in order to determine the most important conditions for the route. The main objective of the optimisation is the minimisation of the total energy consumption (TEC), calculated based on a selection of conditions using the potential flow solver MPUF-3A. Cavitation has been evaluated by the blade designer, through an interactive optimisation method. The results showed that designing and optimising for the most highly loaded condition led to solutions with the lowest TEC. © 2022 The Author(s)

  • 19.
    Gypa, Ioli
    et al.
    Chalmers University of Technology, Sweden.
    Jansson, Marcus
    Kongsberg Maritime Sweden AB, Sweden.
    Gustafsson, Robert
    Kongsberg Maritime Sweden AB, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Propeller design procedure for a wind-assisted KVLCC22022In: PRADS 2022 Book of Abstracts, 2022Conference paper (Refereed)
    Abstract [en]

    Wind-assisted ship propulsion (WASP) has received much attention lately with research focusing on the different sail technologies, ship-hull design optimisation and weather route optimisation. However, the traditional propulsion system is still needed for wind assisted vessels and is associated with several challenges, related to the wide range of operating conditions and propeller loads due to the varying degree of wind-assistance that will occur. In this study we use an interactive design and optimisation methodology applied on propellers of wind-assisted vessels. The methodology involves handling the complete operating profile of the propeller, an optimisation method for interactive cavi-tation evaluation by the blade designer, and the use of a new objective, the total energy consumption (TEC) of the expected operation. We use a case study where the KVLCC2 tanker is retrofitted with six Flettner rotor sails, operating between two fixed destinations at constant speed. The purpose is to investigate to what extent a new propeller design can offer a significantly lower TEC when compared to the existing design. Based on the results of this study, approximately 0.9% further reduction in TEC was achieved with the WASP adapted propeller compared to the existing one.

  • 20.
    Huang, Chen
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Temple, Alastair
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Ramachandra, Vasudev
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Anderson, Johan
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Andersson, Petra
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Modelling thermal runaway initiation and propagation for batteries in dwellings to evaluate tenability conditions2022Report (Other academic)
    Abstract [en]

    Thermal propagation is one of the major challenges when batteries will be used in dwellings in large scale. It means the exothermic reactions in the cell are out of control and can lead to a fast release of flammable and toxic gases. In a system involving a large number of cells, thermal runaway can rapidly propagate from one battery cell to the whole system, which means substantial fire and explosion risks, an event that is important to mitigate and prevent. Multi-physics simulations together with full-scale testing is a cost-effective method for designing safer batteries. This project aims at simulating thermal runaway initiation and propagation using a multi-physics commercial software GT-Suite. 

    A battery thermal runaway model containing 12 prismatic cells based on 3-D Finite Element approach was built using GT-Suite. The computed thermal runaway time instants versus thermal runaway cell number were compared with full-scale experimental data with reasonable agreement. Quantitative sensitivity study on the model input parameters and model space and time resolutions on the computed start time instant and time duration of thermal runaway were performed. The thermal runaway model was then extended with an electric equivalent sub-model to simulate the short circuit. With the electrical model acting as the input to the thermal model, the most interesting output of the simulation is the change in temperature of the cells, dependent on the current in the cells, with respect to time. The current is determined by the value of the external resistance through which the short takes place and the voltage level of the battery pack. The obtained results from the above short circuit simulations can only be used as a starting point and not as absolute values for neither triggering the thermal model nor for accurately simulating a battery under an electrical load. Furthermore, GT-Suite was applied to simulate the gas dispersion inside a room. A comparative study of the dispersion of toxic gases during thermal runaway, utilising an arbitrary release of HCN to represent the battery gases, in a small compartment with natural ventilation was investigated and the results compared the same situation simulated in FDS. The pipe based modelling supported by GT-Suite has limited applicability and overestimated the concentrations close to the ceiling whereas the lateral concentrations where underestimated. 

    The multi-physics model for battery thermal runaway process is promising and worth to be applied with care for designing safer batteries in combination with full-scale testing. 

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  • 21.
    Hörteborn, Axel
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Allision modelling in IWRAP Mk II – A verification and sensitivity study: Chapter 82023In: Advances in the Collision and Grounding of Ships and Offshore Structures: PROCEEDINGS OF THE 9th INTERNATIONAL CONFERENCE ON COLLISION AND GROUNDING OF SHIPS AND OFFSHORE STRUCTURES (ICCGS 2023), NANTES, FRANCE, 11-13 SEPTEMBER 2023, CRC Press, 2023, Vol. 12, p. 51-58Chapter in book (Refereed)
    Abstract [en]

    Risk assessment is important both while planning to build new infrastructure and for maintenance of existing structures. The probability of ship-structure allisions could be estimated with IWRAP Mk II, which is a commonly used software for estimating maritime risks. However, the research coverage of the software is limited with regards to groundings and allisions. The aim of this study is to verify how IWRAP Mk II estimates the accident probability. To perform this verification a separate tool is constructed, OMRAT, based on the same theory as IWRAP Mk II. The aim is also to highlight the sensitivity of different parameters in these types of models. It is concluded that IWRAP Mk II estimates the probability of allisions and groundings with the same equations. Another conclusion is that some parameters have a linear effect on the accident probabilities and other parameters are also influenced by the model layout.

  • 22.
    Hörteborn, Axel
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Hassellöv, Ida-Maja
    Chalmers University of Technology, Sweden.
    Economic incentives and technological limitations govern environmental impact of LNG feeder vessels2023In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 429, article id 139461Article in journal (Refereed)
    Abstract [en]

    In the transition to sustainable shipping, Liquified Natural Gas (LNG), is proposed to play a role, reducing emissions of sulphur and nitrogen oxides, and particulate matter. However, LNG is a fossil fuel and there is an ongoing discussion regarding the extent of methane slip from ships operating on LNG, challenging the assumptions of LNG as a sustainable solution. Here we show another aspect to consider in the environmental assessment of shipping; LNG feeder vessels may spend as much as 25% of their time at sea just running the ship to ensure the pressure in the tanks are not exceeded, i.e., run time not directly attributed to the shipment of gas from one port or ship, to another. In other words, the economic incentives are currently allowing for roughly 32% increase of the ships’ operational emissions and discharges and increased navigational risks. Most coastal areas are heavily affected by anthropogenic activities and e.g., in the Baltic Sea there is consensus among the HELCOM member states that the input of nutrient and hazardous substances must be reduced. Even if the LNG feeder vessels are currently few, the possibility to reduce their environmental impact by 32% should be an attractive opportunity for future policy measures and investigation of technological solutions of the problem. 

  • 23.
    Hörteborn, Axel
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Ringsberg, Jonas W
    Chalmers University of Technology, Sweden.
    A method for risk analysis of ship collisions with stationary infrastructure using AIS data and a ship manoeuvring simulator2021In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 235, article id 109396Article in journal (Refereed)
    Abstract [en]

    The study presents a methodology that uses AIS data and a ship manoeuvring simulator to simulate and analyse marine traffic schemes with regard to risks for accidents. An event identification method is presented, which is needed for the accident scenario part of the methodology. This is based on AIS data, where the Great Belt VTS area was used to verify the methodology. Three events that could result in ship-bridge allisions were modelled and simulated in the simulator: drifting ship, sharp turning ship and miss of turning point. The Monte Carlo method was used to perform large number of simulator runs, including a parameter sensitivity analysis. The probability of a ship allision against the Great Belt Bridge was calculated to be 0.007. Analysis of the ship-bridge allision cases was shown to be dominated by the event drifting ship. This event has a relatively low kinetic energy at the impact, and the expected allision energy for a 1,000-year allision corresponds to a 178 m tanker with 57,870 DWT and ship speed 14.6 knots. Finally, this study presents a mitigation analysis, which shows how the probability of allisions can be reduced by reducing the ship speed or altering the traffic separation scheme. © 2021 The Authors

  • 24.
    Irannezhad, Mohsen
    et al.
    Chalmers University of Technology, Sweden.
    Bensow, Rickard E.
    Chalmers University of Technology, Sweden.
    Kjellberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Eslamdoost, Arash
    Chalmers University of Technology, Sweden.
    Comprehensive computational analysis of the impact of regular head waves on ship bare hull performance2023In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 288, article id 116049Article in journal (Refereed)
    Abstract [en]

    This paper focuses on investigating the impact of waves on ship hydrodynamic performance, enhancing our understanding of seakeeping characteristics and contributing to advanced ship and propeller design. It examines the resistance, motions, and nominal wake of the KVLCC2 bare hull, which is free to surge, heave, and pitch, in both calm water and regular head waves using a RANS approach. The research reveals a substantial dependency of the wake on grid resolution, particularly in calm water and shorter waves, while motions and resistance display a weaker dependency. The computed nominal wake is compared against towing tank SPIV measurements. Utilizing Fourier analyses and reconstructed time series, the study examines correlations among various factors influencing the bare hull’s performance in waves. The axial velocity component of the wake in waves demonstrates significant time variations, mainly driven by higher harmonic amplitudes. This dynamic wake is influenced by instantaneous propeller disk velocities due to hull motions, orbital wave velocities, boundary layer contraction/expansion, bilge vortex and shaft vortex dynamics. The wake distribution at the propeller plane not only differs significantly from the calm water wake in longer waves but also exhibits notably larger time-averaged values (up to 21%). 

  • 25.
    Irannezhad, Mohsen
    et al.
    Chalmers University of Technology, Sweden.
    Bensow, Rickard E
    Chalmers University of Technology, Sweden.
    Kjellberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Eslamdoost, Arash
    Chalmers University of Technology, Sweden.
    Towards Uncertainty Analysis of CFD Simulation of Ship Responses inRegular Head Waves2021In: Proceedings of the 23rd Numerical TowingTank Symposium, NuTTS 2021, 2021Conference paper (Refereed)
    Abstract [en]

    Ship hydrodynamic performance prediction in waves is a common practice in the early stages of the ship design process as the interaction between the ship and waves may adversely affect the hydrodynamic responses of the ship in comparison to calm water. Various well­established numerical and experimental methods are often utilized for prediction of ship performance in waves. Although the model tests are expensive and time­consuming, a high level of accuracy is often achieved in such experiments. On the other hand, with respect to the increased computational power, prediction of ship performance in waves by the numerical methods based on Computational Fluid Dynamics (CFD) techniques are gradually acquiring more popularity. However, the validity of the incorporated discretization schemes and modelling assumptions in these state­of­the­art CFD methods are often overlooked and the method accuracy is mainly assessed through the validation of the results based on the respective model test data. Validation as an engineering exercise aims to show that the right equations are solved, while verification (mathematical exercise) is required to demonstrate that equations are solved right [1]. The eventual objective of this research is to perform verification and validation exercises of a ship performance prediction in regular head waves using CFD, whereas in this paper, the working progress is presented which may be subjected to significant revisions. To this end, extensive attempts have been made to investigate numerical wave propagation without the presence of the hull. Ship responses in waves are significantly influenced by the wave excitation forces. Therefore, not only high level of accuracy is required for the simulation of the numerical waves, but also quantification of the numerical uncertainties are of a great importance. This becomes even more challenging when the ship hydrodynamic responses, such as motions and added resistance in waves, exhibit dependencies on wave steepness. In this paper, the main focus of such uncertainty analyses is on the systematic grid convergence study.

  • 26.
    Irannezhad, Mohsen
    et al.
    Chalmers University of Technology, Sweden.
    Eslamdoost, Arash
    Chalmers University of Technology, Sweden.
    Kjellberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Investigation of ship responses in regular head waves through a Fully Nonlinear Potential Flow approach2022In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 246, article id 110410Article in journal (Refereed)
    Abstract [en]

    In this study, the hydrodynamic performance of a ship in terms of motions and resistance responses in calm water and in regular head waves is investigated for two loading conditions using a Fully Nonlinear Potential Flow (FNPF) panel method. The main focus is understanding the ship responses in a broad range of operational conditions. Comprehensive analyses of the motions and their correlation with the wave making resistance including their harmonics in waves are presented and compared against experimental data. The predicted motions compare well with experimental data but the resistance prediction is not quite as good. The natural frequencies for heave and pitch are estimated from a set of free decay motion simulations in calm water to provide a better insight into the ship behavior near resonance conditions in waves. Interestingly, in addition to the well known peak in the added wave resistance coefficient around wave lengths close to one ship length, a secondary peak is detected in the vicinity of wave lengths with half the ship length. © 2022 The Authors

  • 27.
    Kanchiralla, Fayas Malik
    et al.
    Chalmers University of Technology, Sweden.
    Brynolf, Selma
    Chalmers University of Technology, Sweden.
    Olsson, Tobias
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Ellis, Joanne
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Hansson, Julia
    Chalmers University of Technology, Sweden; IVL Swedish Environmental Research Institute, Sweden.
    Grahn, Maria
    Chalmers University of Technology, Sweden.
    How do variations in ship operation impact the techno-economic feasibility and environmental performance of fossil-free fuels?: A life cycle study2023In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 350, article id 121773Article in journal (Refereed)
    Abstract [en]

    Identifying an obvious non-fossil fuel solution for all ship types for meeting the greenhouse gas reduction target in shipping is challenging. This paper evaluates the technical viability, environmental impacts, and economic feasibility of different energy carriers for three case vessels of different ship types: a RoPax ferry, a tanker, and a service vessel. The energy carriers examined include battery-electric and three electro-fuels (hydrogen, methanol, and ammonia) which are used in combination with engines and fuel cells. Three methods are used: preliminary ship design feasibility, life cycle assessment, and life cycle costing. The results showed that battery-electric and compressed hydrogen options are not viable for some ships due to insufficient available onboard space for energy storage needed for the vessel’s operational range. The global warming reduction potential is shown to depend on the ship type. This reduction potential of assessed options changes also with changes in the carbon intensity of the electricity mix. Life cycle costing results shows that the use of ammonia and methanol in engines has the lowest life cycle cost for all studied case vessels. However, the higher energy conversion losses of these systems make them more vulnerable to fluctuations in the price of electricity. Also, these options have higher environmental impacts on categories like human toxicity, resource use (minerals and metals), and water use. Fuel cells and batteries are not as cost-competitive for the case vessels because of their higher upfront costs and shorter lifetimes. However, these alternatives are less expensive than alternatives with internal combustion engines in the case of higher utilization rates and fuel costs.

  • 28.
    Kim, Keunjae
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Leer-Andersen, Michael
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Roughness Effects on Ship Design and Operation2021In: Part of the Lecture Notes in Civil Engineering book series (LNCE, volume 63), Springer Science and Business Media Deutschland GmbH , 2021, p. 186-204Conference paper (Refereed)
    Abstract [en]

    Hull surface condition plays an important role for ships performances for new-built ships as well as ships in operation since the drag penalties due to hull roughness are substantial. It is a standard practice that ship design is based on performance evaluation by model testing of ship models with hydrodynamically smooth surface and the increase of resistance for new build condition is added by roughness correlation allowance based on empirical formula. Surface roughness effects beyond the new build condition are seldom considered in the design process. The question is whether hull roughness affects the flow characteristics to such extend that it influence with the resulting design. This is especially important for propellers or energy saving devices which are operating around the stern of the ship where the roughness effects on flow characteristics are most pronounced. This paper will discuss some practical questions related to the effect of hull roughness, both in terms flow characteristics, power increase and impact on ship design and operational practice. 

  • 29.
    Kjellberg, Martin
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Gerhardt, Frederik
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Sailing in waves: A numerical method for analysis of seakeeping performance and dynamic behavior of a wind powered ship2022In: SNAME 24th Chesapeake Sailing Yacht Symposium, CSYS 2022, Society of Naval Architects and Marine Engineers , 2022Conference paper (Refereed)
    Abstract [en]

    Before the background of the internationl Maritime Organization's 2050 emission reducation targets, the largest sailing ship in the world is currently being developed in Sweden. This wind powered car carrier, called Oceanbird, will have four 80-metre-high wing sails targeting CO2savings in the order of 90%. The prediction and analysis of the seakeeping performance of such a ship is of importance, not only in terms of sailing dynamics, but also when it comes to the structural design of the rig. To this end, a numerical method for predicting a ship's motions and loads on its rigid wing sails is described in this paper and a demonstration of how the method can be used to obtain such loads is presented. The numerical method is based on an unsteady 3D fully nonlinear potential flow hydrodynamic model coupled with a hybrid 2D RANS/3D lifting-line aerodynamic model. Simulations in a seaway with short-crested irregular waves and corresponding wind conditions are conducted, resulting in time histories of the aerodynamic and inertial forces acting on the rig. Possible applications of the method include fatigue analysis of the wing sails, where the accumulated fatigue damage over the lifespan of the rig structure depends on the sum of aerodynamic forces and motion induced inertial forces. Other potential applications include sail dynamics, parametric roll, sheeting strategies and appendage configuration studies. 

  • 30.
    Korkmaz, Kadir Burak
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Investigations on experimental and computational trim optimisation methods2023In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 288, article id 116098Article in journal (Refereed)
    Abstract [en]

    Shipping is vital for global trade but also emits significant greenhouse gases. To address this issue, various measures have been proposed, including improved ship design, alternative fuels, and improved operational practices. One such cost-effective operational measure is trim optimisation, which involves operating the ship at the hydrodynamically optimal forward and aft draughts. This study focuses on investigating the trim trends of a RoPax vessel using experimental fluid dynamics (EFD) and computational fluid dynamics (CFD) methods. The trim trends are derived in resistance and self-propelled modes. Multiple CFD methods are examined, along with different extrapolation techniques for experimental results. Uncertainty assessment is conducted for the experimental data, and a verification and validation study is performed. Furthermore, the predictions are compared with real operational data. The findings reveal that determining trim trends solely in towed mode is inadequate due to the profound influence of the operating propeller. Some of the investigated CFD methods demonstrate good agreement with the model test results in self-propelled mode, while others exhibit limitations. By selecting appropriate models and configurations, this study demonstrates that trim trends can be determined with sufficient precision, as evidenced by the comparison between ship operational data and predictions from EFD and CFD methods. 

  • 31.
    Korkmaz, Kadir Burak
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Scaling of wetted-transom resistance for improved full-scale ship performance predictions2022In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 266, article id 112590Article in journal (Refereed)
    Abstract [en]

    Determining a ship's propulsive power is a critical stage in the design phase in which the evaluation of the stern plays a crucial role. Different flow regimes can be observed depending on the position and shape of the transom. This paper investigates the wetted-transom flow characteristics and their implications on the 1978 ITTC Performance Prediction Method. In the case of flow separation, such as the wetted-transom flow, the current ITTC-78 procedure does not provide an alternative method. Therefore, two alternative methods were proposed based on the investigations of CFD computations on seven hull forms. The firstly proposed method is a combined EFD&CFD method called the two form factor method. It requires CFD computations in model and full-scale, and it can handle any case of flow separation, including the wetted-transom flow. The second proposed method is an empirical correction formula for the hulls with a wetted-transom flow. Finally, the full-scale speed-power relations between the speed trials and the full-scale predictions from the two alternative methods and the standard ITTC-78 method were presented. It is observed that the two suggested methods considerably improve the correlation between the predictions and the speed trials. © 2022 The Author(s)

  • 32.
    Korkmaz, Kadir Burak
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Verification and validation of CFD based form factors as a combined CFD/EFD method2021In: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 9, no 1, article id 75Article in journal (Refereed)
    Abstract [en]

    Predicting the propulsive power of ships with high accuracy still remains a challenge. Well established practices in the 1978 ITTC Power Prediction method have been questioned such as the form factor approach and its determination method. This paper investigates the possibility to improve the power predictions by the introduction of a combined CFD/EFD Method where the experimental determination of form factor is replaced by double body RANS computations. Following the Quality Assurance Procedure proposed by ITTC, a best practice guideline has been derived for the CFD based form factor determination method by applying systematic variations to the CFD set-ups. Following the verification and validation of the CFD based form factor method in model scale, the full scale speed-power-rpm relations between large number of speed trials and full scale predictions using the CFD based form factors in combination with ITTC-57 line and numerical friction lines are investigated. It is observed that the usage of CFD based form factors improves the predictions in general and no deterioration is noted within the limits of this study. Therefore, the combination of EFD and CFD is expected to provide immediate improvements to the 1978 ITTC Performance Prediction Method. © 2021 by the authors. 

  • 33.
    Korkmaz, Kadir Burak
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Sakamoto, Nobuaki
    National Maritime Research Institute, Japan.
    Queutey, Patrick
    Ecole Centrale de Nantes, France.
    Deng, Ganbo
    Ecole Centrale de Nantes, France.
    Yuling, Gao
    Shanghai Ship and Shipping Research Institute, China.
    Guoxiang, Dong
    Shanghai Ship and Shipping Research Institute, China.
    Maki, Kevin
    University of Michigan, USA.
    Ye, Hauxian
    University of Michigan, USA.
    Akinturk, Ayhan
    Ocean Coastal and River Engineering, Canada.
    Sayeed, Tanvir
    Ocean Coastal and River Engineering, Canada.
    Hino, Takanori
    Yokohama National University, Japan.
    Zhao, Feng
    China Ship Scientific Research Centre, China.
    Tezdogan, Tahsin
    University of Strathclyde, UK.
    Demirel, Yigit
    University of Strathclyde, UK.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    CFD based form factor determination method2021In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 220, article id 108451Article in journal (Refereed)
    Abstract [en]

    The 1978 ITTC Power Prediction method is used to predict the propulsive power of ships through towing tank testing. The form factor approach and its determination in this method have been questioned. This paper investigates the possibility to improve the power predictions by introducing Combined CFD/EFD Method where the experimental determination of form factor is replaced by double body RANS computations applied for open cases KVLCC2 and KCS, including first-time published towing tank tests of KVLCC2 at ballast condition including an experimental uncertainty analysis specifically derived for the form factor. Computations from nine organisations and seven CFD codes are compared to the experiments. The form factor predictions for both hulls in design loading condition compared well with the experimental results in general. For the KVLCC2 ballast condition, majority of the form factors were under-predicted while staying within the experimental uncertainty. Speed dependency is observed with the application of ITTC57 line but it is reduced with the Katsui line and nearly eliminated by numerical friction lines. Comparison of the full-scale viscous resistance predictions obtained by the extrapolations from model scale and direct full-scale computations show that the Combined CFD/EFD Method show significantly less scatter and may thus be a preferred approach.

  • 34.
    Lee, Jae-Hoon
    et al.
    Seoul National University, South Korea.
    Kim, Yonghwan
    Seoul National University, South Korea.
    Kim, Beom-Soo
    Seoul National University, South Korea.
    Gerhardt, Frederik
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Comparative study on analysis methods for added resistance of four ships in head and oblique waves2021In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 236, article id 109552Article in journal (Refereed)
    Abstract [en]

    This paper presents a comparative study of wave-induced motion responses and the added resistance of a ship. Four representative types of ships are adopted as test models: LNG carrier, tanker, containership, and bulk carrier. Two experimental techniques—captive and free-running model tests—are conducted under regular head and oblique wave conditions to create benchmark data. Several numerical computation methods (asymptotic formula, 2D strip theory, 3D panel method, and CFD) are applied to perform the seakeeping analysis. The comparison results indicate that the accuracy and reliability of each analysis technique are validated, and its characteristics and limitations are investigated with respect to the physical aspects of the added resistance caused by a wave. The analysis results are compared based on how steady flow-induced coupling effects are considered. Further, the sensitivities of seakeeping quantities with respect to wave steepness were examined based on the results of linear and fully nonlinear computations. The overall tendency of the added resistance in accordance with the incident direction of a wave is discussed. © 2021 The Author(s)

  • 35.
    Lidstrom, D
    et al.
    Chalmers University of Technology, Sweden.
    Lundh, T
    Chalmers University of Technology, Sweden.
    Marimon Giovannetti, Laura
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Agent based match racing simulations: Starting practice2022In: SNAME 24th Chesapeake Sailing Yacht Symposium, CSYS 2022, Society of Naval Architects and Marine Engineers , 2022Conference paper (Refereed)
    Abstract [en]

    Match racing starts in sailing are strategically complex and of great importance for the outcome of a race. With the return of the America's Cup to upwind starts and the World Match Racing Tour attracting young and development sailors, the tactical skills necessary to master the starts could be trained and learned by means of computer simulations to assess a large range of approaches to the starting box. This project used game theory to model the start of a match race, intending to develop and study strategies using Monte-Carlo tree search to estimate the utility of a player's potential moves throughout a race. Strategies that utilised the utility estimated in different ways were defined and tested against each other through means of simulation and with an expert advice on match racing start strategy from a sailor's perspective. The results show that the strategies that put greater emphasis on what the opponent might do, perform better than those that did not. It is concluded that Monte-Carlo tree search can provide a basis for decision making in match races and that it has potential for further use. 

  • 36.
    Lindborg, Jenny
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Electrification and Reliability.
    Forsström, Ellinor
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Ivarsson, Stefan
    RISE Research Institutes of Sweden, Safety and Transport, Electrification and Reliability.
    Hamon, Camille
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Falkendal, Theresa
    Nilsson Energy, Sweden.
    Nilsson, Hans-Olof
    Nilsson Energy, Sweden.
    Större tankar - Det samhällsekonomiskt lönsamma i att subventionera vätgastankstationers infrastruktur2021Report (Other academic)
    Abstract [sv]

    Det svenska elsystemet står inför en rad utmaningar. En ökande andel intermittent energi ställer ökade krav på balansering i våra nät, dessutom pågår en samhällsomfattande elektrifiering samtidigt som nyetablerade industrier ställer höga krav på tillgängligheten av effekt. Parallellt pågår ett omfattande arbete att minska Sveriges utsläpp av växthusgaser. Vätgas väntas anta en nyckelroll; främst inom industrin men även inom transportsektorn. Etableringen av en storskalig användning av vätgas öppnar samtidigt upp för att skapa energinyttor i andra delar av samhället, inte minst vad det gäller att stötta upp elnäten genom att erbjuda energilagringskapacitet och flexibilitet. I denna studie har ett framtidsscenario (år 2045) utretts. Det bygger på data från Svenska kraftnät samt på två hypotetiska utvecklingstrender; 1. Vätgas har antagit en dominerade roll inom elektrifieringen av transportsektorn. Vätgastankstationer är lika vanligt förekommande som dagens bränslestationer för vägbundna fordon. 2. Nämnda vätgastankstationer skalar upp vätgaslagringskapaciteten för att parallellt med att tillgodose transportbehovet även skapa nätnytta på transmissionsnätsnivå och därigenom minska behovet av investeringar i nätförstärkningar. Studiens syfte har varit att utreda den tekniska potentialen för ovanstående framtidsscenario, samt att undersöka hur en sådan utveckling av tankstationernas verksamhet skulle kunna komma att påverka priset på vätgas som bränsle. Dessutom har det i studien utretts om den ekonomiska besparing som de uteblivna nätförstärkningarna medför hade varit tillräckliga för att skapa politiska styrmedel i form av ett investeringsstöd riktat till ägare av tankstationerna för att täcka installationskostnaden för de utökade lagren. De nättekniska analyserna har i studien begränsats till att utreda vätgasens potentiella nätnytta vid handelsgränser på stamnätsnivå mellan elområden i Sverige samt vid förbindelser till våra grannländer. Studien har också begränsats till att enbart undersöka nätnyttan vid de handelsgränser som har ett förväntat behov av nätförstärkningar i framtiden. Resultat av studien visar: • Utökade lager vid vätgastankstationer kan skapa ett visst stöd till transmissionsnätet där handelsflödet når gränsen för den maximala handelskapaciteten. Förutsättningen är att det enbart inträffar stundtals och vid tidpunkter utspridda över året. Den totala nätnyttan är således väldigt begränsad. Ett fåtal undantag för detta har noterats där nätnyttan blir mer betydande. I dessa fall krävs dock en betydligt större bränslecellskapacitet vid de tänkta tankstationerna än vad som kan tänks vara standard för en vätgastankstation för att kunna tillhandhålla tillräcklig effekt i nätet. • Den utökade lagringskapaciteten vid tankstationerna har stor påverkan på vätgaspriset. Två parametrar som är av stor betydelse för detta är elpris och 6 (72) CAPEX (investeringskostnad). Ett investeringsstöd på minst 50% behövs för att priset på vätgas ska bli lägre för en tankstation med ett lager på 4 000 kg (utökat lager, även inkluderande en bränslecell på 300 kW), jämfört med ett lager på 100 kg (standard-lager). • Det råder begränsade förutsättningarna för ett betydande investeringsstöd för vätgastankstationer enbart baserat på den nätnytta som vätgastankstationer kan generera på transmissionsnätnivå. Två faktorer som visats ha stor betydelse för resultatet är valet av styrstrategi för hur lagerkapaciteten ska kunna nyttjas av näten samt tillgänglig bränslecellskapacitet vid tankstationerna. • Mer omfattade stödsystem blir möjliga först när fler ”vätgas-nyttor” vägs in. Det sakas dock idag kunskap om hur ett sådant stöd skulle utformas. Utöver ovanstående resultat genomförs en inventering av andra ”nyttor” som tankstationerna skulle kunna bidra med, både mot nätet men andra energimarknader. Sammanfattningsvis kan det konstateras att decentraliserade vätgastankstationer utgör ett intressant inslag i den framtida energimarknaden med flera potentiella användningsområden. Det råder också goda möjligheter för att bygga mer komplexa affärsmodeller/ekonomiska styrmedel då fler nyttor tas i beaktande. Av studien framgår det tydligt att även om nyttan av tankstationernas lager är begränsad på stamnätsnivå är möjligheterna betydligt större på lägre nätnivåer. I dessa sammanhang är det mer troligt att vätgasen kan komma att ta en mer betydande roll.

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  • 37.
    Marimon Giovannetti, Laura
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Dhome, U.
    KTH Royal Institute of Technology, Sweden.
    Malmek, Karolina
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Persson, A.
    Chalmers University of Technology, Sweden.
    Wielgosz, C.
    KTH Royal Institute of Technology, Sweden.
    Multi-wing sails interaction effects2022In: SNAME 24th Chesapeake Sailing Yacht Symposium, CSYS 2022, Society of Naval Architects and Marine Engineers , 2022Conference paper (Refereed)
    Abstract [en]

    The effects of multiple wings interacting and the change in efficiency due to those effects as well as optimal sheeting angles are becoming an important area of study with the advent of wind-propelled ships for goods transport. This research presents a first analysis of wind tunnel tests carried out at the University of Southampton R.J. Mitchell wind tunnel where three wings are subject to turbulent flow with Reynolds number in excess of 1 million. A range of possible variations of ship heading and apparent wind angles are tested taking into consideration the blockage effects and the geometrical characteristics of the working section. The forces and moments are captured on each individual wing as well as in the overall wind tunnel balance with 6-components dynamometers. Furthermore, pressure sensors and PIV data are recorded during the tests to provide the experimental campaign with results that can validate both qualitatively and quantitatively the numerical tools developed to aid the design stage of wind propelled vessels. 

  • 38.
    Marimon Giovannetti, Laura
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Farousi, Ali
    Chalmers University of Technology, Sweden.
    Ebbesson, Fabian
    Chalmers University of Technology, Sweden.
    Thollot, Alois
    INP ENSEEIHT, France.
    Shiri, Alex
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Eslamdoost, Arash
    Chalmers University of Technology, Sweden.
    Fluid-Structure Interaction of a Foiling Craft2022In: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 10, no 3, article id 372Article in journal (Refereed)
    Abstract [en]

    Hydrofoils are a current hot topic in the marine industry both in high performance sailing and in new passenger transport systems in conjunction with electric propulsion. In the sailing community, the largest impact is seen from the America’s cup, where boats are sailed at more than 50 knots (over 100 km/h) with 100% “flying” time. Hydrofoils are also becoming popular in the Olympics, as in the 2024 Olympic games 5 gold medals will be decided on foiling boats/boards. The reason for the increasing popularity of hydrofoils and foiling boats is the recent advances in composite materials, especially in their strength to stiffness ratio. In general, hydrofoils have a very small wetted surface area compared to the wetted surface area of the hull. Therefore, after “take-off” speed, the wetted surface area of the hull, and consequently the resistance of the boat, is reduced considerably. The larger the weight of the boat and crew and the higher the speeds, the greater the loads on the hydrofoils will be. The current research investigates the interaction effects between the fluid and structure of the ZP00682 NACRA 17 Z-foil. The study is carried out both experimentally, in SSPA’s cavitation tunnel, and numerically using a fully coupled viscous solver with a structural analysis tool. The experimental methodology has been used to validate the numerical tools, which in turn are used to reverse engineer the material properties and the internal stiffness of the NACRA 17 foil. The experimental flow speed has been chosen to represent realistic foiling speeds found in the NACRA 17 class, namely 5, 7, and 9 m/s. The forces and the deflection of the Z-foil are investigated, showing a maximum deflection corresponding to 24% of the immersed span. Finally, the effects of leeway and rake angles on the bending properties of the Z-foil are investigated to assess the influence of different angles in sailing strategies, showing that a differential rake set-up might be preferred in search for minimum drag. © 2022 by the authors. 

  • 39.
    Marimon Giovannetti, Laura
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Ljungqvist, Kasper
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Variation of underwater appendages and their effects on wind powered ships2021In: 7th High Performance Yacht Design Conference, HPYD 2021, The Royal Institution of Naval Architects , 2021Conference paper (Refereed)
    Abstract [en]

    Assessing the manoeuvring performances of a ship early in the design stage is becoming ever more important, especially now that wind-assisted propulsion is radically increasing in popularity as a measure to reduce fuel consumption. For conventionally propelled vessels most of the forces are in the longitudinal direction. Some, relatively small, drift angles and rudder angles are encountered in order to compensate for side forces due to environmental conditions. For a wind-propelled vessel on the other hand, side forces are an inevitable consequence of the propulsion choice and it is of utmost importance to balance these side forces with a matching hydrodynamic design to efficiently propel the vessel forward avoiding travelling for longer periods of time. In order to counteract those large side forces, it is necessary to add underwater appendages. Their position along the hull will determine the centre of lateral resistance (CLR) that needs to be related to the aerodynamic centre of effort (CoE) in order to achieve a balanced ship. The research herein described, compares towing tank captive tests with Virtual Captive Tests (VCT) derived from Computational Fluid Dynamics (CFD) simulations and the effects of generated side forces and moments when the inflow angles are varied. Adding a set of diagonal foils to the hull, in the investigated case reduces the leeway angle of approximately 2 degrees in close-hauled conditions.

  • 40.
    Marimon Giovannetti, Laura
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Stenius, Ivan
    KTH Royal Institute of Sweden, Sweden.
    Review of undewater fluid-structure interaction measuring techniques2021In: 7th High Performance Yacht Design Conference, HPYD 2021, The Royal Institution of Naval Architects , 2021Conference paper (Refereed)
    Abstract [en]

    This research aims to provide a feasibility study for an underwater Fluid Structure Interaction (FSI) experimental methodology. The possibility of measuring a structural deflection under fluid load and the flow behaviour around the structure is particularly interesting with the rise of composite materials, due to their inherent flexibility that permits them to be designed to a range of loading conditions. A review study on the experimental methodology available is carried out so that, in the future, a FSI measurement system can be installed in an underwater environment such as a towing tank or a marine basin. A robust and repeatable experimental methodology will also provide researchers with a validation case for numerical FSI simulations. The feasibility study starts with a thorough investigation of the existing measuring systems with an assessment of what could be used in SSPA Sweden underwater facilities (i.e. towing tank and marine dynamics laboratory). Currently there is a lack of FSI experimental methods, especially for underwater environment. The large majority of the current studies does not account for the complexity of the FSI coupled problems, where the structural response affects the flow behaviour and vice-versa. Bringing different techniques together will allow simultaneous measurements to be taken in a dynamic underwater environment. This would be especially important for performance prediction and numerical codes validations of foiling structures to assess the effects of deflections and twist when phenomena like cavitation and ventilation occur.

  • 41.
    Oliveira, D. R.
    et al.
    Chalmers University of Technology, Sweden.
    Lagerström, Maria
    Chalmers University of Technology, Sweden.
    Granhag, Lena
    Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Larsson, Ann I
    University of Gothenburg, Sweden.
    Ytreberg, Erik
    Chalmers University of Technology, Sweden.
    A novel tool for cost and emission reduction related to ship underwater hull maintenance2022In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 356, article id 131882Article in journal (Refereed)
    Abstract [en]

    International shipping plays a vital role in the world's transport system and economy. However, shipping faces challenges in terms of reducing its environmental and health impact, namely emission of greenhouse gases, air pollutants, and chemical substances to the marine environment. In particular, the roughness condition of underwater surfaces of a ship hull affects the ship's energy efficiency, with marine growth (biofouling) and mechanical roughness leading to propulsion powering penalties. Measures to control biofouling, using antifouling coatings and in-water hull cleaning, may also be associated with significant impacts to the marine environment. In the current study, a new tool is presented, HullMASTER (Hull MAintenance STrategies for Emission Reduction), which aims at enabling the shipping industry and authorities in the Baltic Sea region to make evidence-based decisions on hull maintenance strategies. HullMASTER simulates emissions to air and water, to calculate the differences in economic cost for operators, as well as health- and environmental damage costs between different hull maintenance scenarios. Validation of HullMASTER predictions against 40 vessel-years of in-service performance data on propulsive performance, with operations in the Baltic Sea region, shows good agreement, averaging within 5 percentage-point difference in propulsion penalty. Further, a scenario-based demonstration of HullMASTER on a general cargo vessel shows that, in the comparison between a silicone foul-release coating and business-as-usual scenario of a biocidal coating, retrofitting the coating to a foul-release coating can result in significant savings for society, i.e., along with marginal savings in cost for ship operators. Results for such comparisons and analysis will however be dependent on specific vessel cases and operational profiles, thence the value of an interactive tool such as HullMASTER. © 2022 The Authors

  • 42.
    Orych, Michal
    et al.
    FLOWTECH International AB, Sweden; Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Larsson, Lars
    Chalmers University of Technology, Sweden; ISYD AB International School of Yacht Design, Sweden.
    Roughness effect modelling for wall resolved RANS – Comparison of methods for marine hydrodynamics2022In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 266, article id 112778Article in journal (Refereed)
    Abstract [en]

    This paper deals with several aspects of surface roughness modelling in RANS codes applied to full-scale ship simulations. To select a method that is suitable for wall-resolved RANS solvers and gives reliable results at high Reynolds numbers, five different roughness models are compared. A grid uncertainty analysis is performed and the sensitivity to the grid resolution close to the wall (y+) is investigated. The results are compared to extrapolated results of experiments carried out with rough plates with various heights and roughness types. A correlation factor between the Average Hull Roughness and the equivalent sand roughness height is investigated, and a value of five is deemed the most suitable. The work suggests that the Aupoix-Colebrook roughness model gives the best results for full-scale ship simulations, at least with the current code, and that the near-wall grid resolution required for smooth surfaces can be applied also for the rough case. © 2022 The Authors

  • 43.
    Orych, Michal
    et al.
    Chalmers University of Technology, Sweden; FLOWTECH International AB, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Larsson, Lars
    FLOWTECH International AB, Sweden.
    Validation of full-scale delivered power CFD simulations2021In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 238, article id 109654Article in journal (Refereed)
    Abstract [en]

    Verification and Validation of CFD simulations of delivered power at full-scale are carried out for a single screw cargo vessel. Numerical simulations are performed with a steady-state RANS method coupled with a body force propeller model based on a lifting line theory. There are no significant differences in the uncertainty levels between model and full-scale computations. The finest grid exhibits the numerical uncertainty of 1.40% at full-scale. Computed results are compared with sea trial data for three sister ships. Special attention is paid to the effect of roughness on the hull and propeller. The comparison error for the delivered power is about 1% which is significantly lower than the experimental uncertainty. © 2021 The Authors

  • 44.
    Orych, Michal
    et al.
    Chalmers University of Technology, Sweden; FLOWTECH International AB, Sweden.
    Östberg, Magnus
    FLOWTECH International AB, Sweden.
    Kjellberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Larsson, Lars
    Chalmers University of Technology, Sweden; ISYD AB International School of Yacht Design, Sweden.
    Speed and delivered power in waves — Predictions with CFD simulations at full scale2023In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 285, article id 115289Article in journal (Refereed)
    Abstract [en]

    An efficient numerical method is proposed to estimate delivered power and speed loss for a ship in wind and waves. The added resistance in waves, obtained with an unsteady potential flow panel method, is added to the calm water resistance from a steady-state potential flow/RANS method coupled with a body force propeller model for self-propulsion. A comparison of numerical and experimental results is made for added resistance, calm water resistance and delivered power. A good agreement is obtained. As a practical application, the approach is used to calculate the weather factor, fw, of the Energy Efficiency Design Index (EEDI). The calculated weather factor is consistent with the values derived from full-scale measurements included in a database of similar ships. © 2023 The Author(s)

  • 45.
    Prabahar, N. S. S.
    et al.
    University of Gothenburg, Sweden.
    Larsson, L.
    Chalmers University of Technology, Sweden.
    Persson, Adam
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Split-flaps for increased heel stability of t-foil configurations2021In: 7th High Performance Yacht Design Conference, HPYD 2021, The Royal Institution of Naval Architects , 2021Conference paper (Refereed)
    Abstract [en]

    Horizontal T-foils allow for maximum lift generation within a given span. However, for T-foils, the lift force acts in the symmetry plane of the boat, thereby producing no righting moment. It results in a lack of transverse stability during foil-borne sailing. In this project, we propose a system, where the height-regulating flap on the trailing edge of the foil is split into a port and a starboard flap, whose angle is adjusted proportionally to the heel. Such a system generates and scales the righting moment based on the heel angle, making the boat easier to balance. The effectiveness of this system is studied for a custom-made double-handed skiff using a dynamic velocity prediction program (DVPP), especially in the take-off phase. It is shown that the split flap system generates a larger righting moment for the foiling boat than for the non-foiling one at boat speeds above 3 m/s.. The improved stability comes at a cost of additional induced resistance and this effect is computed by CFD. It is shown, using the DVPP, that the increased resistance, slows down the boat at the lowest wind speeds, but above 2.5 m/s true wind, the split flap boat is as fast as the boat with a single flap around the racecourse. Due to the higher stability, less depowering of the sails is required, and that compensates for the increased resistance. 

  • 46.
    Raza, Zeeshan
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. University of Gothenburg, Sweden.
    Woxenius, J.
    University of Gothenburg, Sweden.
    Vural, C. A.
    Chalmers University of Technology, Sweden.
    Lind, Mikael
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Digital transformation of maritime logistics: Exploring trends in the liner shipping segment2023In: Computers in industry (Print), ISSN 0166-3615, E-ISSN 1872-6194, Vol. 145, article id 103811Article in journal (Refereed)
    Abstract [en]

    Rapidly evolving needs of shippers, rising competition, advancement in digital technologies and a quest to increase cost and operational efficiencies are all driving the digital transformation of maritime logistics. However, in contrast to other industries such as media, telecom, banking, retail and even other traffic modes, the often family-controlled and network-centric liner shipping industry has historically been conservative in adopting innovations; hence, it is still far behind in embracing digitalization. Based on semi-structured interviews with senior executives of liner shipping companies, this study explores the current digital maturity levels, the opportunities provided by digitalization and the underlying challenges that hinder its implementation in the liner shipping segment within the larger maritime logistics industry and identifies the essential leading strategies of digitalization in this segment. The digital maturity categories applied to liner shipping provide an opportunity for practitioners in this industry to evaluate their business functions’ digital maturity levels. Furthermore, based on interview data, digital transformation for the maritime logistics industry is defined, as well as 9 major barriers and 19 different pathways to digital transformation are identified. Understanding the key challenges and success factors in the industry is a key to approaching digitalization problems and developing a healthy digital transformation process. © 2022 The Authors

  • 47.
    Rogerson, Sara
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Costa, Nicole
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Ekholm, Johan
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Besker, Terese
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Janhäll, Sara
    RISE Research Institutes of Sweden, Built Environment, Energy and Resources.
    Linders, Torsten
    University of Gothenburg, Sweden.
    Anderberg, Patrick
    E-sea, Sweden.
    SeaCharging - Investigating the Need for Standardised Charging Infrastructure for Maritime Electrified Vessels2022Report (Other academic)
    Abstract [en]

    The transport sector, including maritime transport, is facing accelerating electrification, where it is important that charging infrastructure is developed in parallel with electrified vessels. In today's few examples, charging technology is adapted to specific vessels and conditions. The possibility of using standards and standardisation to increase the efficiency of introducing electrified vessels has been the focus of the SeaCharging project. The middle segment of ships, such as waterborne public transport, is facing a rapid increase in electrification.

    The project begins with an exploratory analysis of the current situation with charging stations in Sweden. This analysis covers the obstacles, needs and opportunities in different shipping segments and geographical areas. This results in an informative review providing input to standardisation committees, but also ports and shipping companies. Dissemination of the project’s results was achieved via a workshop, a number of seminars and this final report directed at the maritime, energy, technology, and standardisation communities. Together with Lighthouse, we will in early 2023, do a broad workshop for the whole sector, presenting the final project results and putting them into a wider context.

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  • 48.
    Rogerson, Sara
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Santén, Vendela
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Sallnäs, Uni
    Linköping University, Sweden.
    The influence of power and trust on the initiation and duration of modal shift solutions2021In: Sustainability, E-ISSN 2071-1050, Vol. 13, no 7, article id 3757Article in journal (Refereed)
    Abstract [en]

    Modal shift to more energy-efficient alternatives, such as from road to rail or sea, is one path to reduce negative environmental effects. Transport providers and shippers have crucial roles in modal choice decisions, and a better understanding of the influence of interorganisational factors on modal shift is needed. The purpose is to increase the understanding of opportunities for modal shifts by exploring the influence of power and trust at the interface between transport providers and shippers. Aspects of power (coercive, reward, legitimate, expert and referent) and trust (con-tractual, competence and goodwill) influencing modal shifts were identified from interviews with shippers and transport providers in Sweden. During the initiation phase of modal shift, power ap-pears more important, while trust is shown essential for the duration. By proactively suggesting modal shift, transport providers can use expert power to create rewards and referent power, through recognition of their expertise. Building trust, particularly goodwill trust, such as time in-vested in understanding the other party, transparency about challenges and jointly seeking solu-tions, is key to establish long-term modal shifts. This paper contributes to modal shift literature with insights on power balances and trust between transport providers and shippers. © 2021 by the authors. 

  • 49.
    Rogerson, Sara
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Svanberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Santén, Vendela
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Supply chain disruptions: flexibility measures when encountering capacity problems in a port conflict2022In: The International Journal of Logistics Management, ISSN 0957-4093, Vol. 33, no 2, p. 567-589Article in journal (Refereed)
    Abstract [en]

    Purpose: There can be many negative effects from a disruption in a central node of companies' supply chains, such as a port conflict that reduces capacity. Strategies for disruption management include flexibility and redundancy. This paper aims to analyse a supply chain disruption from flexibility and capacity perspectives. Design/methodology/approach: A case study was conducted of the supply chain disruption caused by the port conflict in 2016–2017 in Gothenburg, in which the port operated at a reduced capacity. Companies importing and exporting goods, freight forwarders, hauliers, train operators, ports, shipping companies and their agents were interviewed. Findings: Various capacity problems (ports, links, container chassis, empty containers) were encountered due to the port conflict. Flexibility measures such as node, mode and fleet flexibility can be used in response to changes in capacity. Difficulties with applying flexibility are discussed. Research limitations/implications: Although based on a Swedish case, findings are relevant for disruptions or other types of disturbances in ports elsewhere and also in other important nodes in companies' supply chains. Practical implications: Actors influenced by disturbances in a port can increase their understanding of potential capacity problems and flexibility measures. Readiness and timely action are important due to competition regarding capacity. Originality/value: The implications on the transport network surrounding a port, including many actors, are explained, illustrating how capacity problems propagate, but there is some flexibility to manage the problems. 

  • 50.
    Rosenstatter, Thomas
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Melnyk, Katarina
    RISE Research Institutes of Sweden, Digital Systems, Mobility and Systems.
    Towards Synthetic Data Generation of VANET Attacks for Efficient Testing2023In: IEEE Intelligent Vehicles Symposium, Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2023Conference paper (Refereed)
    Abstract [en]

    Vehicle-to-Vehicle communication can improve traffic safety and efficiency. This technology, however, increases the attack surface, making new attacks possible. To cope with these threats, researchers have made a great effort to identify and explore the potential of cyberattacks and also proposed various intrusion or misbehaviour detection systems, in particular machine learning-based solutions. Simulations have become essential to design and evaluate such detection systems as there are no real publicly available Vehicular Ad-Hoc Network (VANET) datasets containing a variety of attacks. The drawback is that simulations require a significant amount of computational resources and time for configuration.In this paper, we present an attack simulation and generation framework that allows training the attack generator with either simulated or real VANET attacks. We outline the structure of our proposed framework and describe the setup of a standard-compliant attack simulator that generates valid standardised CAM and DENM messages specified by ETSI in the Cooperative Intelligent Transport Systems (C-ITS) standards. Based on the introduced framework, we demonstrate the feasibility of using deep learning for the generation of VANET attacks, which ultimately allows us to test and verify prototypes without running resource-demanding simulations. 

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