Change search
Refine search result
1234 1 - 50 of 176
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Ahlsén, David
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Fartygsprojektering och Flytande havsbaserad vindkraft2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Den här rapporten behandlar tre områden anknutna till den gemensamma sektorn marina system. Inledningsvis beskrivs sjöfartsnäringens olika delar däribland olika typer av gods och fartygstyper samt sjöfartens aktörer och reglerande organ. Sjöfarten diskuteras med hänsyn till miljö och visar att godstransport till havs är relativt energieffektivt, men att alla typer av gods inte kan motiveras ur ett hållbart perspektiv.

    En inledande fartygsprojektering genomförs för ett transportscenario där 5500 ton kiwifrukt ska transporteras från Nya Zeeland till länder kring Östersjön inom en tidsrymd som garanterar att frukten håller god kvalitet. Fartygstypen är ett kylfartyg dimensionerat att rymma lasten, minimera motstånd och uppfylla stabilitetskriterier från IMO. För att uppfylla transportscenariot är fartyget designat för en marschfart på 20 knop, med ett deplacement på 12500 ton, en längd på 138 m, 21 m i bredd och ett djupgående på 7.7 m.

    Avslutningsvis identifieras kriterier och förutsättningar för flytande havsbaserad vindkraft. Detta med syfte genomföra en inledande projektering av en vindkraftpark stor nog att Gotland kan täcka sin elkonsumtion med endast förnybara energikällor. Parken anläggs längs en ny kabelanslutning mellan Gotland och fastlandet utom synhåll från såväl Gotland, Öland och fastlandet. Området uppfyller krav på vindförhållanden och utgörs av 24 vindkraftverk med kapacitet på 5 MW vardera.

  • 2.
    Al-Khalili Szigyarto, Cristina
    et al.
    KTH, School of Biotechnology (BIO), Proteomics.
    Garme, Karl
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Högfeldt, Anna-Karin
    KTH, School of Education and Communication in Engineering Science (ECE), Lärande.
    Magnell, Marie
    KTH, School of Education and Communication in Engineering Science (ECE), Lärande.
    Vägen från student till ingenjör: exempel från två kandidatexamenskurser och ett förslag om en programsammanhållande byggnadsställning2011Conference paper (Other academic)
  • 3. Allen, T.
    et al.
    Battley, M.
    Casari, P.
    Kerling, B.
    Stenius, Ivan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Westlund, Joacim
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Structural responses of high performance sailing yachts to slamming loads2011In: 11th International Conference on Fast Sea Transportation, FAST 2011 - Proceedings, 2011, 585-592 p.Conference paper (Refereed)
    Abstract [en]

    Experimental measurements of transient strains, local accelerations and pressure were undertaken on the IMOCA Open 60' class sailing yacht Paprec-Virbac III, and on a replica hull panel section tested in a laboratory slam testing facility. The approximately 1m x 0.7m panel for laboratory testing was manufactured on a mould taken from the plug used for the vessel construction, ensuring that the panel had identical curved geometry to the vessel. The laboratory panel included two stringers as on the same region of the vessel. An instrumentation layout including arrays of resistance strain gauges, accelerometers and a transient pressure transducer was used. Linear displacement transducers were used to measure panel deformations during the laboratory tests. The laboratory testing was undertaken at a range of constant impact velocities from 0.5 to 3m/s using a Servohydraulic Slam Testing System. Sea-trials were undertaken in the Hauraki Gulf, Auckland New Zealand. There was good qualitative agreement between the field and laboratory measurements in regard to timing and relative magnitudes of strains at different positions on the structure. Results demonstrate that the hull structure undergoes very complex transient deformations during the slamming events.

  • 4.
    Allen, Tom
    et al.
    Centre for Advanced Composite Materials, University of Auckland, New Zealand.
    Battley, Mark
    Centre for Advanced Composite Materials, University of Auckland, New Zealand.
    Stenius, Ivan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Experimental Methods For Determining Shear Loads In Sandwich Structures Subjected To Slam Loading2010In: 9th International Conference on Sandwich Structures, 2010Conference paper (Other academic)
  • 5.
    Amundin, Eskil
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Modeling of fatigue in RORO ships2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The largest modern Pure Car and Truck Carriers (PCTC’s) are typically 230 meters long and have 13 cargo decks. In order to facilitate rapid loading and unloading these ships have been subject to a development of reducing any obstructing structures in the cargo hold, meaning that the transversal shear preventing structures, i.e. the racking bulkheads, has been taken to a minimum. Previous studies have concluded that some points on the racking bulkheads, as a result of the stripped down design, are subject to high stresses resulting from wave induced accelerations of the ship.

    In this M.Sc. Thesis the fatigue life of a corner of a transverse bulkhead opening in a 230 meter long PCTC with a capacity of 7200 cars is calculated with different methods.

    •Fatigue life is calculated from recorded ship motion data with the notch stress method in conjunction with rain flow counting and the cumulative damage principal.

    • Fatigue life is calculated according to (DNV CN. 30.7, 2010), based on a Lloyd’s Register FE model load case.

    • Actual findings on the ship are compared to the calculated results. Due to the lack of inspection data this comparison is not very extensive and only more briefly discussed.

    It is concluded that the fatigue life of the examined point, calculated from recorded motion data is 9.6 years and the fatigue life according to DNV is 8.0 years. It is also found that the fatigue damage is cumulated in almost discrete portions and thus the calculated fatigue life can be inaccurate when a short period of time is evaluated as is done in this thesis.

    A modification to the racking bulkhead with respect to fatigue life is also analyzed and it is concluded that the fatigue life in the examined point could be extended significantly by some simple modifications to the geometry.

  • 6.
    Andersson, Ricky
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Naval ArchitectureRICKY ANDERSSONrickya@kth.se0739-5332522015-06-2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    På allt senare tid har sjöfarten blivit allt mer eftertraktat och ett nödvändigt transportsätt för att frakta de saker som krävs och önskas av oss människor oavsett var på jorden man är. Det finns många olika sorters av fartyg desginade för olika ändamål som t.ex. roro-fartyg för frakt av fordon, containerfartyg för frakt av containers, bulkfartyg för frakt av olja, kol, malm, trä och passagerarfärjor för frakt och nöjesresor med människor.

    Två bulkfartyg har tagits fram för att klara av att frakta 235 000 ton järnmalm(pellets) och har en marschfart på 13,5 knop. Den låga farten gör att kostnaden för frakten kan hållas nere och ändå klara leveransmålet som är 450 000 ton pellets per månad från Narvik, Norge till New York City, USA. Fartyget har slankhetstalet 0,85, vilket nästan motsvarar en fyrkantig låda, allt för att få en stabil gång under färd. Fartyget har en längd på 333 meter och en bred på 57 meter. Motoreffekten för att driva fartyget är 17 000 kW inkluderat en säkerhetsmarginal med 15 % för extremt väder eller tidspress.

    Energibehovet i världen är stora och på grund av att de förnyelsebara energikällorna inte räcker till använder man sig av fossila bränslen. Att hitta olja och gas som är ett fossilt bränsle kräver mycket arbete, både i planering samt utrustning. En del av den olja och gas finns offshore och kräver fartyg för transportering och tömning från oljeriggarna men kan också användas för prospektering.

    Riskerna är dock väldigt stora i denna bransch och måste tas i största beaktning. Det är dyra investeringar i kampen om att hitta de naturtillgångar som finns kvar. Det har i dagsläget blivit aktuellt att undersöka och prospektera i arktiska områden som är helt outforskat, detta ställer givetvis ännu större krav på utrustning och riskerna ökar.

  • 7.
    Antonatos, Alexandros
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Parametric FE-modeling of High-speed Craft Structures2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The primary aim of the thesis was to investigate aluminum as building material for high speed craft, study the hull structure design processes of aluminum high speed craft and develop a parametric model to reduce the modeling time during nite element analysis. An additional aim of the thesis was to study the degree of validity of the idealizations and the assumptions of the semi-empirical design methods by using the parametric model.

    For the aluminum survey, a large amount of scientic papers and books related to the application of aluminum in shipbuilding industry were re-viewed while for the investigation of hull structure design, several designs of similar craft as well as all the classication rules for high speed craft were examined. The parametric model was developed on Abaqus nite ele-ment analysis software with the help of Python programming language. The study of the idealizations and the assumptions of the semi-empirical design methods was performed on a model derived by the parametric model with scanltings determined by the high speed craft classication rules of ABS.

    The review on aluminum showed that only specic alloys can be applied on marine applications. It also showed that the eect of reduced mechanical properties due to welding could be decreased by introducing new welding and manufacturing techniques. The study regarding the hull structure de-sign processes indicated that high speed craft are still designed according to semi-empirical classication rules but it also showed that there is ten- dency of transiting on direct calculation methods. The developed paramet-ric model does decrease the modeling time since it is capable of modeling numerous structural arrangements. The analysis related to the idealizations and the assumptions of the semi-empirical design methods revealed that the structural hierarchy idealization and the method of dening boundary by handbook type formulas are applicable for the particular structure while the interaction eect among the structural members is only possible to be studied by detailed modeling techniques.

  • 8.
    Asgeirsson, Gunnar Steinn
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Hydrodynamic Investigation of WavePower Buoys2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the increasing global demand for energy and environmental awareness, the interestin sustainable energy solutions has grown over the last years including wave energy.In this thesis there is a literature study on Wave Energy Converters (WEC) and a theorychapter on the power in ocean waves. The thesis work was done in in collaboration withCorPower Ocean (CPO), an innovative company developing a WEC. Two buoy shapes,both with two dierent weights were investigated and a comparison made on the eectof latching on power absorption. The work can be separated into two main parts, anumerical simulation and experimental tests.A numerical model incorporated with a mathematical description of CPO Power Take-o(PTO) physics was used to simulate and obtain numerical results on the buoy behaviourin select sea states. The benet of latching was obtained by comparing passively heavingbuoys to latch controlled buoys. The simulation model was used for various analysis ofthe system.Experiments were performed at 1:30 scale on the same buoys in a tank facility. Informationabout the hydrodynamics of the buoy, motion and power absorption was obtainedand the eect of latching on the power absorption found.Results on natural period and radiation damping were obtained and a drag coecientwas estimated.The results show that phase control by latching can substantially increase the powerabsorption of a point absorber and broaden the range of waves it can operate in. Agreementwas found in the numerical model and the experiments when investigating thebenet of latching compared to passively heaving.

  • 9. Battley, Mark A.
    et al.
    Allen, Tom D.
    Pehrson, Petter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Stenius, Ivan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Rosén, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Effects of Panel Stiffness on Slamming Responses of Composite Hull Panels2009In: 17th International Conference on Composite Materials, ICCM17, 2009, 1-11 p.Conference paper (Refereed)
    Abstract [en]

    Controlled water slam testing of composite hull panels was conducted to study the effect of hydroelasticity for three panels with different stiffnesses. The experimental methodology successfully characterised the hydroelastic behaviour, which included kinematic as well as inertial effects. Hydroelastic effects included changes in panel geometry, local velocity, fluid pressures, and panel structural responses.

  • 10.
    Battley, Mark
    et al.
    Centre for Advanced Composite Materials, University of Auckland, New Zealand.
    Stenius, Ivan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Dynamically Loaded Marine Composite Structures2003In: 14th International Conference on Composite Materials, 2003Conference paper (Other academic)
  • 11.
    Battley, Mark
    et al.
    Centre for Advanced Composite Materials, University of Auckland, New Zealand.
    Stenius, Ivan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Breder, Johan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Edinger, Susan
    High Modulus (NZ) Ltd, Auckland, New Zealand.
    Dynamic Characterization of Marine Sandwich Structures2005In: 7th International Conference on Sandwich Structures: Advancing with Sandwich Structures and Material, 2005, 537-546 p.Conference paper (Other academic)
    Abstract [en]

    Dynamic experimental and theoretical methods for sandwich panel structures subjected to water slamming are described, including a unique servo-hydraulic controlled slam test system and a pressure based transient finite element technique. The pressure simulation method accurately represents the pressures observed in slamming tests, and the transient dynamic finite element modelling can simulate sandwich panel responses to a slamming load.

  • 12.
    Bayer, Johannes
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    THE DUCKLING PROJECT: Design and manufacturing of autonomous surface vehicles for various application areas2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the times of big data analyses and fast robotic evolution, collecting data is an important part of science. Today we have only explored 5 percent of the ocean, which is less than we have explored Mars. To collect more data of the ocean we need tools, vehicles and equipment, which are designed and used by scientists.  In this technical report, the design of an autonomous surface vehicle (ASV) is described. An ASV is a floating vehicle that can conduct manoeuvres and actions autonomously. The ocean environment is in many senses difficult for technically operated vehicles, with the main reasons being high pressure, no possibility of radio communication and of course water, which always is a challenge when combined with water. The concept of this work is to provide a system which consists of four equal ASV units, who can perform different operations. The system should be capable of conducting different kinds of experiments with varying testing equipment. Two ideas have been considered: autonomous depth mapping of inshore areas and locating and following an acoustic source. These two possible scopes are used to find fitting and flexible requirements for the ASV. In the future, the four units should be used by different projects realised by students and researchers, therefore robustness in operation and usability are a main point of focus when determining the requirements.

  • 13. Bačkalov, I.
    et al.
    Bulian, G.
    Cichowicz, J.
    Eliopoulou, E.
    Konovessis, D.
    Leguen, J. -F
    Rosén, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Themelis, N.
    Ship stability, dynamics and safety: Status and perspectives from a review of recent STAB conferences and ISSW events2016In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 116, 312-349 p.Article, review/survey (Refereed)
    Abstract [en]

    In Naval Architecture, the concept of "stability" has a very wide meaning, embracing ship stability fundamentals with ship dynamics and ultimately ship safety. As such, the subject is of paramount importance for its wide implications on design and operation of ships and floating units. Research in this field has, therefore, an important impact on the fleet safety, and the International Conferences on Stability of Ships and Ocean Vehicles (STAB Conferences) and the International Ship Stability Workshops (ISSW) are certainly the venues where expertise and contemporary developments in this specific field tend to be collected and thoroughly debated. With the aim of analysing the current status and possible future perspectives of research in the field of ship stability, dynamics and safety, this paper provides an extensive review of the findings presented at STAB Conferences and ISSW events in the period 2009-2014. The reviewed material is organised according to a set of identified macro-topics of research. On the basis of the reviewed material, consolidated research topics as well as emerging subjects are laid out, and ideas for possible future research are also brought forward. Discussion is also provided regarding the link between research and educational aspects.

  • 14. Bačkalov, I.
    et al.
    Bulian, G.
    Rosén, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Shigunov, V.
    Themelis, N.
    Improvement of ship stability and safety in intact condition through operational measures: Challenges and opportunities2016In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 120, 353-361 p.Article in journal (Refereed)
    Abstract [en]

    Attaining a sufficient level of safety from the point of view of stability is typically considered to be a matter of design. However, it is impossible to ensure safety only by design measures, and operational measures can then represent a complementary tool for efficiently and cost-effectively increasing the overall safety of the vessel. Time could therefore be coming for systematically considering operational measures as a recognised and regulated integral part of a holistic approach to ship safety from the point of view of stability. This paper therefore aims at capturing recent trends of research targeting operational safety measures, with specific attention to the intact ship condition. Open challenges and opportunities for research are identified, potential benefits and shortcomings of different options are discussed, and needs and possibilities for further developments in this area are explored. As an overall goal, this paper aims at providing food for thoughts as well as a ground for further proceeding towards the target of implementing a virtuous integrated approach to intact ship safety, from the point of view of stability, which gives due credit to effective and robust operational risk control options.

  • 15.
    Berg, Johan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Better design of wheel-loaded decks2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study treats the design of secondary structures for wheel-loaded decks. It concludes that significant savings in structural weight, overall cost and environmental impact can be obtained by an improved design. The rules of three classification societies are examined and their principle differences are discussed. Weight and cost optimal solutions of rule-based design are identified for a deck of a typical short-sea RoRo-vessel. The rule-optimal designs are assessed and further improved on the basis of FEcalculations and the economic and environmental benefits associated with the best solutions are approximated.

  • 16.
    Berggren, Axel
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Lindh, Ebba
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    ICE LOADS AND RESISTANCES ON A SMALL COMMUTER VESSEL: A comparative study of rule based design and analytical ice loads and resistances2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of the thesis is to investigate what the results are when applying DNV ice class design rules on a vessel that falls outside the validity range and how it does compare to direct calculations. The vessel to be investigated is a smaller ice going commuter ferry intended for freshwater Lake Mälaren in Stockholm.

    Due to increased need of public transport in the area, political decisions have been made to incorporate ferry lines in the public transport system. The number of commuters’ peak during January and February and it is thus necessary to design a ferry that works all year around, in all possible weather conditions, including the ice conditions that occur winter time (Rindeskär, 2014).

    In order to make a comparative study of the DNV ice class and direct calculations with regards to resistances and structural loads on the hull, a general arrangement of the ferry is developed. Icebreaking resistance models based on DNV ice class (Det Norske Veritas, 2014), Riska (Riska, Willhelmson, Englund, & Leiviskä, 1997) and Lindqvist (Lindqvist, 1989) can be compared based on the ferry’s main data. The bow section of the hull is designed to handle the DNV design pressure according to DNV ice class 1C. The structural response is investigated using a finite element model, applying different load cases given from DNV as well as from the studied semi empirical ice load models mentioned above.

    The bow design is of great importance for the icebreaking performance and the speed. The greater the stem angles the higher the resistance. A large variation in the results was also noted as only Lindqvist’s model took the freshwater ice properties into account. Further measurements have to be made in freshwater for smaller vessels to validate the results.

    In the FE-analysis it was seen that the hull structure coped well with the DNV design pressure of 1 MPa. However, the empirical design pressure of 1.5 MPa resulted in too high stresses in the structure. The result indicates that the design rules work well for the intended design pressure, but the minimum empirical design pressure is still higher than the DNV design pressure for the commuter vessel. It can be that the DNV design rules can be used in the case of the ferry, but further investigations has to be made with regards to minimum design pressure.

    In general, the results can be used as a basis for further investigations in the field of vessels operating in freshwater ice conditions.

  • 17.
    Bergsek, Mattias
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    THRUST PREDICTION PROGRAM FOR MARINE JET POWER2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Marine Jet Power, MJP wishes to investigate the possibility of transforming their current Thrust Prediction Program, TPP written in C++ source code into a more up to date tool for their sales staff. The old TPP, though an accurate and precise tool, is not documented and lacks commentaries in the source code. Therefore the beginning of this master thesis was about documenting and investigates what methods were used to calculate the performance of the water jet system.The next step was splitting the long C++ source code in to smaller functions, this was done using MatLab where several m-files were created with the different functions in. C++ syntax and structure differs from MatLab so the source code must be translated in to MatLab syntax. Once the new TPP was translated and the calculation results were identical with the old TPP a Graphical User Interface, GUI was created and presented to MJP. The current MatLab TPP is not finished, only two of four calculation modes have been translated and MJP wants modifications in the GUI. The additional work needed in order to have the sales tool MJP wishes is currently discussed.

  • 18.
    Björnsson, Lars
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Comparison of Idealized 1D and Forecast 2D Wave Spectra in Ship Response Predictions2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Commonly, when calculating ship responses one uses idealized wave spectra to represent the sea. In the idealized model, the sea is frequently assumed to consist of swell and windwaves, which are usually represented by idealized 1D wave spectra, and the directionality of wind-waves is accounted for by multiplication with a standard spreading function. In operational response predictions these idealized spectra are typically generated by extracted parameters from real directional 2D wave spectra obtained from a weather forecast, i.e. spectra that reflects the sea state conditions for the particular place and time. It is generally not known in a statistical sense how large the errors become when idealized wave spectra are used to represent 2D wave spectra, especially not regarding the directionality. The objective with the study is hence to assess the errors that arise when adopting this simplification.

    The analysis compares three ship types that cover different combinations of hull form, load condition and operational conditions: a 153m RORO ship, a 219 m PCTC and a 240m bulk carrier. Chosen response parameters are roll motion, vertical acceleration and wave added resistance, which were calculated in 12240 sea states, for 10 speeds and 36 courses for each ship. The sea states are forecast 2D spectra from the North Atlantic 25th of September 2012. Transfer functions were generated from the hull geometry and realistic load conditions at speeds 2-20 knots. For each sea state-speed-course combination, responses were calculated for 2D wave spectra and corresponding generalized spectra. The error is taken as the difference in response between results obtained with 2D and idealized spectra, using 2D-results as reference. Several statistical measures were used to represent the errors for one sea state with only one number, and among them the root-mean-square error (RMSE) and the worst possible error (WPE) are regarded most relevant.

    The results show that the relative error decreases with increasing share of wind waves and decreasing share of swell. Multi-directionality of wind waves causes large errors only for small waves, and it is concluded that for higher sea states (for which the wind waves are predominant) the Bretschneider representation with spreading function leads to small relative errors. Absolute errors are considered the only relevant for investigating the effect of the error on seakeeping calculations. In general, the RMS acceleration levels are in the order of percentages of one g for all ships. For the bulker, WPE and RMSE for wave added resistance was found to be 8.3% and 3.8% of the total calm-water hull resistance in general, and almost 50% in worst case. The roll angle bias could reach up to 15. Also, the effect of ship speed was investigated, and it shows that the error increases in general with higher speed. It is concluded that it is necessary to use 2D spectra in order to avoid large errors, and to keep performance predictions correct on average.

  • 19.
    Blomberg, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Gross, Jonas
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Conceptual Study of a USV for theSwedish Navy2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis is an initial conceptual study of an unmanned surface vehicle (USV) for the

    Swedish Navy. The purpose is to highlight challenges and possibilities connected to

    unmanning a vessel and to suggest one specific concept.

    Generating one concept meant weighing characteristics of different hull types against one

    another to derive a valuable compromise. The generated concept includes a feature of

    longitudinal bulkheads separating an inner, dry volume from outer ballast volumes. The

    latter fill with seawater at low velocities, causing the hull to partly submerge which in turn

    decreases signature and increases ballistic protection within the semi-submerged speed

    range. The!concept!measures 6.2 by 2.3 meters, weigh, approximately 1800 kg and may

    reach a calm water top speed of 44 knots. Investigating needs and potentials of an

    unmanned vessel within the Swedish Navy resulted in a set of requirements, including the

    possibility to arm the USV. This study investigates feasibility of carrying the SAAB Trackfire

    remote weapon platform aboard.

    Development of the initial USV concept was focused on aspects of naval architecture,

    including the making of a!general arrangement, evaluating materials, a structural design,

    stability and power need analysis. Although unmanned vessels are likely to be subject to

    lessened structural safety factors as opposed to manned, scantling determination is based

    on DNV rules for classification of High Speed, Light Craft and Naval Surface Craft.

     

  • 20.
    Brodin, Felix
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Kandidatexamensarbete Marina system KTH 20152015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport innehåller både en fartygsprojektering och en undersökning huruvida man med hjälp av kraftdrakar kan minska bränsleförbrukningen på oceangående motortrålare. Fartygsprojekteringen gäller ett RoRo-fartyg som ska frakta 300 lastbilar, inklusive passagerare och trailers varje vecka till Åbo respektive till Oxelösund, medan den sistnämnda undersökningen är gjord på en Diesel Duck 462 - en typ av fritidsbåt för helt andra ändamål. Syftena med dessa undersökningar skiljer sig så pass mycket att de tilldelas varsina separata abstrakt.

    I fartygsprojekteringen ingår utöver ett designförslag på själva fartyget även ett designförslag på en tillhörande propeller. De två metoderna som tillämpas för denna propellermodellering förklaras separat i ett Propellerappendix i bilaga 3, där även tillhörande Matlab-koder återfinnes. Som bilaga finns även en kort essä om sjöfart i stort – se bilaga 6.

  • 21.
    Burman, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Kuttenkeuler, Jakob
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Comparative Life Cycle Assessment (LCA) of the Hull of a High Speed Craft2011In: 16th International Conference on Composite Structures / [ed] Prof Antonio Ferreria, 2011Conference paper (Other academic)
  • 22.
    Burman, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Kuttenkeuler, Jakob
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Comparative Life Cycle Assessment (LCA) of theHull of a High Speed CraftIn: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085Article in journal (Other academic)
    Abstract [en]

    A comparative Life Cycle Assessment (LCA) has been performed on the hull of a 24 meter long high speed patrol craft. The aim of the study is to compare different structural materials concepts to determine differences and sensitivities in environmental impact, especially in relation to the total impact including fuel burn. The material concepts studied are aluminium and various composite combinations consisting of glass fibre and carbon fibre with vinyl ester resin both as single skins and as sandwich with a Divinycell foam core. For each material concept a unique and weight optimized structural design was employed fulfilling the DNV high speed craft design code [1]. All identical systems and components for the five hull concepts are omitted in the LCA and hence a comparative study is performed focused on the hull structure. The commercial software SimaPro have been utilized for the LCA calculations and the impact assessment method chosen is the CML Baseline 2000.

    The structural optimization carried out in [1] show that a weight reduction by to up to 50% (on the hull) could be achieved by switching from aluminium to a carbon fibre sandwich concept. The weight reduction switching from glass fibre single skin to a carbon fibre sandwich concept is roughly 20%.

     

    The LCA study performed herein shows that, regardless of hull material concept, the environmental impact is by large dominated by the usage phase due to relatively large fuel consumption. A lower structural weight will reduce the fuel consumption and hence the environmental impact. This is illustrated in fig. 1 for the aluminum hull. All different phases of the life cycle are plotted for all environmental impact categories assessed herein. The green color is related to the operation phase and the red is the manufacturing phase. As observed the operation phase is dominating.

     

    In fig. 2 are the results from the LCA presented for all hull concepts and for all environmental impact factors. The Al-hull is the concept with highest structural weight (red bars) and hence was found to have the highest environmental impact. The carbon fibre sandwich hull (green bars) had the lowest weight of the five and consequently the lowest environmental impact.

    In the normalization analysis performed, in which different impact factors are assessed using a common impact unit, three impact factors stand out as dominating, independent of hull concept; Abiotic depletion, Global warming and Acidification. All these impact factors are herein associated with the usage phase and diesel consumption. If the operation phase is omitted and only the manufacturing phase (including the material extraction/manufacturing) is studied the observation is that the aluminium concept still will have the largest environmental impact for all categories. The most significant environmental impact is now on the marine and the fresh water aquatic ecotoxicity which is associated with the aluminium raw material excavation and manufacturing processes.

     

  • 23.
    Burman, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Kuttenkeuler, Jakob
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Stenius, Ivan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Garme, Karl
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Rosen, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Comparative Life Cycle Assessment of the hull of a high-speed craft2016In: Journal of Engineering for the Maritime Environment (Part M), ISSN 1475-0902, E-ISSN 2041-3084, Vol. 230, no 2, 378-387 p.Article in journal (Refereed)
    Abstract [en]

    A comparative Life Cycle Assessment is performed for different structural material concepts on a 24-m-long high-speed patrol craft. The study is comparative and determines the differences in and sensitivities to environmental impact, especially in relation to the total impact of fuel burn for the different material concepts. The material concepts are aluminium and various composite combinations consisting of glass fibre and carbon fibre with vinyl ester resin both as single skins and as sandwich with a Divinycell foam core. Commercially available standard Life Cycle Assessment software is used for the Life Cycle Assessment calculations. The study shows that regardless of hull material concept, the environmental impact is dominated by the operational phase due to relatively large fuel consumption. In the operational phase, the lightest carbon-fibre concept is shown to have least environmental impact. Considering the manufacturing phase exclusively for the different hull concepts, it is concluded that the manufacturing of the aluminium hull has a somewhat larger environment impact for the majority of Life Cycle Assessment impact categories in comparison to the different composite hulls. The significant impact on the marine and the fresh water aquatic ecotoxicity originates from the aluminium raw material excavation and manufacturing processes. It is shown that the lightest hull, the carbon-fibre sandwich concept, with a 50% structural weight reduction compared to the aluminium design, can be utilized to reduce the fuel consumption by 20% (775 ton of diesel) over the lifetime with significant impact on the dominating environmental aspects considered herein, abiotic depletion, global warming and acidification.

  • 24.
    Burman, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Rosén, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Zenkert, Dan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Spectrum Slam Fatigue Loading of Sandwich Materials for Marine Structures2010Conference paper (Other academic)
    Abstract [en]

    Sandwich materials are more frequently used in high speed craft and ferries. The motivation is reduced weight and associated operational cost. The hull structure in these vessels is subjected to repeated (fatigue) slamming loads (high strain rate loading). Scantling societies treat sandwich materials differently in their design rules. In common reduction or safety factors on the static strength of sandwich materials are used calculating the design stress. In most rules there is no explicit consideration of fatigue performance nor of the altered material properties related to high strain rate loading. In this work actual response measurements on a high speed vessel are used to formulate a tentative slam fatigue loading spectrum for sandwich core materials. This spectrum is then used in the testing of one type of core material common in hulls panels, Divinycell H200. The slam spectrum fatigue results are then compared to fatigue test results based on constant amplitude loading based on a method of equivalent stress. Earlier studies indicate that slamming fatigue do not affect the life compared to constant amplitude loading. However there are also studies that indicate that both a static overload (post the yield point) prior to fatigue loading, and block sequence fatigue loadings with initial high amplitudes followed by low amplitude have a detrimental effect of the fatigue life. In the current study both various amplitudes and high strain rates are included in the fatigue loading sequence. The spectrum fatigue results match the fatigue life from the constant amplitude loading. However, the number of samples is limited and the different effects of fatigue at high strain rates and fatigue block sequence are not fully clarified. It is possible that those effects may counteract each other in the current work. Further studies on sandwich foam core material properties and improvement of methods for material characterization is concluded to be of interest and will follow.

  • 25.
    Börjeson, Simon
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Ghawi, Philippe
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Energieffektiv Linjesjöfart Till Och Från Gotland2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    The ferry traffic to Gotland is essential for the island’s ability to live and develop. Yearly, it transports 1,6 million passengers, 500 000 personal vehicles and 750 000 lane meters of freight with four Ro-Pax ferries. The traffic is controlled and subsidized by the Swedish government since 1971 in order to guarantee the inhabitants and industry of Gotland a satisfactory transportation service. As a consequence of the past decades increased traffic quality, mainly due to a decrease in crossing times, the traffic’s environmental impact and costs has also increased.

    The Master Thesis proposes a new energy efficient traffic arrangement that satisfies the users’ preferences in the same extent as today. The report presents the proposed traffic arrangement’s resulting energy demand and approximate costs, its ships, their routes, speeds and daily capacity. The report also presents the self-developed methodology which is used to evaluate and hence generate the final traffic arrangement. The methodology is called E-fleet in its programmed format.

    The Master Thesis, Energy Efficient Ferry Traffic to and from Gotland, shows that the Gotland Ferry Traffic can, with conventional technology, operate with 49 % less carbon dioxide emissions and with 200 million kronor less in fuel costs than today, without decreasing the traffic quality. The economical and environmental savings are achieved through a well planned traffic with suitable tonnage on appropriate routes.

  • 26.
    Cai, Xiaochi
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Ship response estimation in early design stage2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A practical way to estimate the ship response in early design stage is investigated in this thesis. Focus has been put on the ship vertical bending moment and shear force in operation area. ISSC spectrum is used to indicate the sea state. Napa strip method is employed to derive the transfer function. The ship response is thus generated in frequency domain. The vertical bending moment and shear force along the ship are then calculated according to the critical wave case indicated from the response function.

    Based on the results, the validation of DNV-GL rule and IACS rule is discussed. In this case, the overestimation is discovered for the still water vertical bending moment and shear force. On the other hand, there is underestimation in wave vertical bending moment and shear force. The total vertical bending moment and shear force is reasonable. Since only static loads and total loads are required in the rules, the rules are judged as valid in the early design stage.

    The feasibility of Napa strip method has been commented and the Napa strip method is judged practical according to its accuracy and time consumption. For ship design, the wavelength and the wave steepness are the main parameters affecting the loads on hull. The block coefficient is crucial for the nonlinearity in hogging and sagging condition.

    More models, especially other types of ships are expected to be analysed for this topic in future study. Other methods, such as panel method could take into use in the future work. The probability of operation can be further developed based on this study.

  • 27.
    Caillaud, Antoine
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Development of an hydrodynamic hull model for slender planning hulls based on the 2D+t theory2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A two-dimensional Boundary Element Method (BEM) based on potential flow theory is developed. Exact body boundary conditions and fully nonlinear free surface boundary conditions are considered in order to accurately model nonlinear wave-body interactions. The two-dimensional symmetric water entry of a wedge is studied. Gravity effects are generally included and several numerical treatments are performed. Van Karman's theory is used to simulate the first instant of the water entry. A jet cut-off model is developed in order to tackle the problem of a thin water jet running up along the hull. Smoothing and regriding of the free surface profile are implemented and performed at each time step in order to limit numerical errors and instabilities. Reliable pressure results and first encouraging results are obtained when non-viscous flow separation happens.

  • 28.
    Carlsson, Carl-Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Naval Architecture Kandidatexamensarbete2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sjofart

    This chapter is an essay that describes the role of shipping from a historical point of view as well as the impact of shipping on society.

    Fartygsprojektering

    This chapter is a projection of a ship that can transport 120 000 tonnes of crude oil from Venezuela to Seattle in the United states. The result of this projection is two ship that is 265 meters long and 40 meters wide that transport 80 000 tonnes of oil to Seattle before returning to Venezuela. This journey will take 40 days with a speed of 13 knots. The ship fufillls all regulations that it needs to fufilll.

    Fordjupning

    This chapter focuses on a request for information issued by Stockholm county council concerning public transport on water. The routes covered in this report are those planned for Malaren. These routes are at the time for writing of this report non existing. From this RFI, the authors of this chapter have developed three different ships, two catamarans and one single hull vessel, that carry between 70 and 150 persons. The catamarans have the dimensions of 10 x 25 meters with four or six doors each. The doors are 2,5 meters wide, which allow for fast embarkment and disembarkment. The single hull vessel is 20 x 6 meters and has only one door. The catamarans are partially driven by electricity, which is in line with Stockholm county council's vision of a vehicle fleet driven by 90% renewable fuels. To accommodate these ships in port, a pier concept has also been conceived. This pier is a floating one, with automatic gang planks which hold theship in place, when in port.

  • 29.
    Cederlund, Birger
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Product Development; Water-cleaning Device for the Boat Wash, Miniwash2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Antifouling paints are a big enemy to the marine ecosystem.  Many tons of copper,  zinc  and  other  harmful  substances  are  released  into  the  environment each year, in Sweden alone. 

    This study concentrates on the mechanical antifouling method, using boat washes instead, which is a more sustainable alternative. It comes with reduced fuel consumption, increased speed, and moreover, no need for grinding and painting the hull each year. 

    As long as paint residues remain on hulls, but the boat washes are used instead of new paint, it is desired to collect what is scraped of the hulls. By collecting paint flakes and particles accumulated in organic material, the environmental impact is reduced further.  The scope of this Master’s thesis is to design a collection device for the portable boat wash Miniwash. 

    A collection device with a cleaning system was developed using the pump effect from the brushes along with an extra pump to press the contaminated water through a bag filter taking most of the particles. One can expect as much as 70% of   the   harmful   particles   can   be   taken   care   of,   according   to   the   filter manufacturer, based on given conditions and filter bag pore sizes. By always having a  flow of 8  cubic meters per hour through the cleaning system, it  is assumed  that  not  much  of  the  cleaning  water  will  escape,  not  passing  through The bag filter.

  • 30.
    Cheemakurthy, Harsha
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Load case analysis for a resonant Wave Energy Converter2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As we progress beyond the information age, there is a growing urgency towards sustainability. This word is synonymous with the way we produce energy and there is an awareness to gradually shift towards green energy production. Corpower Ocean aims at producing energy by utilizing the perpetual motion of ocean waves through the motion of small floating buoys. Unlike previous designs, this buoy utilizes the phenomenon of Resonance thus greatly enhancing the energy output.

    In the thesis, the simulation model developed by Corpower Ocean to virtually describe the buoy in operation was validated. This was done by comparing forces obtained from buoy scale model experiments, simulation model and ORCAFELXTM software. After satisfactory validation was established, the shortcomings in the simulation model were identified. Next the simulation model was used to generate data for all sea states for a target site with given annual sea state distribution. This information was then used to predict ultimate loads, statistical loads, motions and equivalent load for a given fatigue life and loading cycles. The results obtained are then treated with a statistical tool called Variation Mode and Effect Analysis to quantify the uncertainty in design life prediction and estimate the factor of safety. The information will be used by the design team to develop the buoy design further. Finally the issue of survivability was addressed by checking buoy behavior in extreme waves in ORCAFLEXTM. Different survivability strategies were tested and videos were captured for identifying slack events and studying buoy behavior in Extreme conditions.

    The work aims at validating a technology that is green from environmental and economic point of view.

  • 31.
    Cheemakurthy, Harsha
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Garme, Karl (Contributor)
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Urban waterborne public transport systems: An overview of existing operations in world cities2017Report (Other academic)
    Abstract [en]

    This report aims to collate information on existing waterborne public transport systems in order to provide a resource for cities that may be considering implementing a water transit network. Stockholm City Council has recently expressed interest in expanding its existing inland waterway network to facilitate increased passenger transport capacity within the city and surrounding districts. This report introduces waterway public transportation systems currently operating in 23 cities around the world to provide an overview of the current state of urban water transit globally. Key operational metrics have been identified and described which have been chosen in order to be most relevant in assessing water transport options for cities. Information regarding system organization, route structure, schedules, and vessels have been compiled. In addition, operational factors contributing to the success of existing water transit systems have also been highlighted as per existing literature. Such characteristics introduced in the report overview include transport integration within the wider public transport network, public perception and feasibility of implementation, land use implications, and the role of water transport in tourism and leisure travel. Efforts toward incorporating environmental sustainability are also briefly addressed. Cities have been divided into three broad categories based on the geographic size and passenger carrying capacity of each water transit system. There were 13 cities identified as large scale, 6 as medium scale and 4 as small scale, or in nascent stages of development. Facilities on board vessels and also terminal infrastructure are compared, as well as any unique features or operating characteristics, which are highlighted. Finally, the systems are mapped a scale in order to compare route structures and scope of operation.

  • 32.
    De Alwis, Pahansen
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    METHODS FOR SHOCK ANDVIBRATION EVALUATION APPLIEDON OFFSHORE POWER BOATS2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Vibration is a part of human life. People use vibrations in many useful ways but eventually human exposure to vibration has become an impediment to human life. Health problems due to exposure to

    vibration and shock are common among the crew operating high speed craft (HSC). Whole body vibration and repeated shocks have been identified as one of the major causes for health effects among

    HSC crew. Whole body vibration can affect health, comfort and performance depending on the magnitude, waveform and time of exposure. Therefore it is prudent the significance of consideration of

    human exposure to vibration and shock when deciding the operational envelope of an offshore HSC. This report addresses this question in two correlated parts where it identifies the interrelationship between the

    human exposure to vibration and shock and the operational envelope of HSC. The first part consists of a state of the art review on methods and measures for evaluation of workplaces exposed to vibrations

    containing multiple shocks and select a suitable method to be used in the second part. The second part is a case study of a Swedish Coast Guard HSC, KBV 476, which describes crew exposure to shock and

    vibration using the method selected from the state of the art review, and discusses the results in relation to the risks involved with the crew in the perspective of short and long term exposure. Nature of the

    vibration exposure and the corresponding risk involved is then discussed with respect to the operational envelope of the craft.

  • 33.
    Detlefsen, Olof
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Predicting the Effects of Interaction between Yachts Sailing Upwind2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The ever-growing yachting industry has come to play an important role in the maritime sector, resulting in an increasing demand for highly technologically advanced cruising and racing sailing yachts. In the aim of producing faster yachts and faster sails designers and sailors has come a long way understanding the science of sailing. While the theories and reality of airflow around one or more sails is widely explored the influence of introducing another yacht in close proximity is however not. The principal value of investigating the influence of interaction between yachts would apply to methods of using this knowledge to create an advantage in a racing situation. In extension practical applications would be on-board decision support software rather than progression of yacht and sail design.

    The aim of this thesis project is to create a greater understanding for the phenomena of interaction and how to better predict the effects of interaction by conducting a series of experiments in The University of Auckland Twisted Flow Wind Tunnel. A general approach to the problem was used including investigation of obvious factors such as the yachts relative position, sail trim and wind angle but also more specific factors such as heel angle and sail design were considered.

    After establishing the distribution and range of significant interaction influence, a 3-dimensional flow field mapping was performed following an investigation attempting to quantify the influence of 2-dimensional versus 3-dimensional effects. Evaluation of different techniques for measuring interaction and the accuracy of the measurements has been fundamentally important throughout the project.

    The results, presented as a summary of performed wind tunnel tests, show the effects of interaction that may be experienced for a specific sailing scenario (Stage 1) and how the theory of interaction may be approached in three dimensions (Stage2)

    The implication of these results reveals the difficulty of fully explaining all aspects of the interaction phenomena or even more so creating a theoretical model valid for all conditions and scenarios. With consideration made to the limitations and possibilities of an creating an empirical model addressed in this report extensive full-scale testing may however serve as sufficient input to future decision support software.

  • 34.
    Deutsch, Clemens
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Gao, Yedun
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Development of a Sonar forUnderwater Sensor Platformsand Surface Vehicles2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the frame of a thesis project the authors have developed software and methodologies for a sonar prototype. The ultimate goal is the installation of the sonar prototype on the department’s sensor platforms, which include AUVs and ASVs.

    The thesis presents the intelligent sampling algorithms and DSP tools, e.g. a matched filter, that have been implemented. The sonar was successfully configured to work as an echo sounder. Tests were performed in the underwater laboratory at FOI and in-situ in the Stockholm archipelago. It was found that the sonar is capable of measuring distances with an average error of less than 1 cm in controlled experiments. The in-situ experiments in Baggensfjärden showed a echo detection rate of ≈90 %.

    Unfortunately, due to hardware limitations, attempts to implement DVL functions have failed. However, background theory and methodologies for velocity measurements, communication and positioning are briefly explained to provide a basis for future work.

    The electronics currently are subject to improvements and a new version is expected to be ready for use soon. Future work will include analysis and integration of velocity sensing, communication protocols and positioning concepts.

  • 35.
    Djurberg, Ebba
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    SANDWICH VERSUS SINGLE SKIN: Material Concept of a Patrol Boat in a Life Cycle Cost Perspective2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report describes the Master Thesis Project "Single Skin Versus Sandwich: Material Concept of a Patrol Boat in a Life Cycle Cost Perspective" performed at Kockums AB, Karlskrona, and reviewed and graded at the Royal Institute of Technology, Stockholm.

    There are both economic and environmental gains of developing fuel-efficient (light) vessels. Kockums have successfully produced ships in sandwich composite material, which is a light and stiff but expensive material concept. Building a vessel in single skin composite might result in a lower total life cycle cost due to several factors. Kockums wish to acquire more information of the affecting factors thus they have initiated this project.

    The project includes analyzing the accumulated cost of a concept patrol vessel while changing five variables: class notation ("Patrol" or "Passenger"), operational profile (10 or 35 knots), material concept (sandwich or single skin), material (carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP)) and choice of propulsion system (controllable pitch propeller (CPP), Inboard Performance System (IPS) or water jet) resulting in 48 versions of the vessel. First, the structural arrangement was adapted to the design loads of each version by iteratively seeking the maximal structural utilization of the elements. This was done by using a computational tool (RSTRUCT) that allows for effective scantling calculation. Then, the material, production and operational cost were determined for each version and the break-even points in terms of years of operation were found.

    The results gave insights concerning the characteristics of the different material concepts. The single skin versions were found to be both heavier (70 %) and more costly in terms of material and production cost (17 %) in relation to their sandwich equivalents. The break-even points between CFRP versions and GFRP versions were ranging between 4 and 14 years, depending on operational profile. For example, for a very low speed profile passenger vessel the break-even point was 40 years, implying that the GFRP version was the most beneficial choice. Regarding propulsion choices, the IPS system was the best choice for every version due to its high overall propulsive coefficient in a broad speed range.

  • 36.
    Draksharam, Manohara Ranganath
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Modelling of Elastic Ship in Waves2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ships in the seas undergo different distortions like bending, twisting or combined bending and twisting. The demand for increase in length and speed of the ships is increasing due to this the study for flexibility of structures is becoming important. Usually the structural excitations or natural frequencies of structure are given less priority since the natural frequencies of the structure are higher than encounter frequencies but since the length and speeds are increasing the encounter frequencies are closer to the fundamental frequencies. The structural behavior can be analyzed by semi-empirical formulation developed by classification societies but the flexibility of its application is limited.The present thesis work deals with the vertical motions of the ship structure. The thesis work is divided in to two parts the first part deals with the literature review of the global loads and Hydroelasticity and the second part deals with the modeling of the structural dynamic problem. In the modeling part Hydro-elasticity theory proposed by Bishop and Price on Euler Bernoulli beam is used for solving the structural dynamic problem and the illustration of springing and whipping is presented. An attempt has also been made to study the dynamic structural responses for a particular hull with the hydrodynamic forces and added mass from high speed strip program developed at KTH and the study has been performed to analyze the influence of various parameters like added mass, damping and stiffness.

  • 37.
    Edström, Kristina
    et al.
    KTH, School of Education and Communication in Engineering Science (ECE), Lärande.
    El Gaidi, Khalid
    KTH, School of Education and Communication in Engineering Science (ECE), Lärande.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Kuttenkeuler, Jakob
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Integrated assessment of diciplinary and interpersonal skills - student perceptions of a novel learning experience2005In: 13th International Symposium at the Oxford Centre for Staff and Learning Development - Improved Student Learning Through Assessment, 2005Conference paper (Other academic)
  • 38.
    Edström, Kristina
    et al.
    KTH, School of Education and Communication in Engineering Science (ECE), Lärande.
    El Gaidi, Khalid
    KTH, School of Education and Communication in Engineering Science (ECE), Lärande.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Kuttenkeuler, Jakob
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Integrated Assessment of Diciplinary, Personal and Interpersonal Skills in a Design-Build Course2005In: 1st CDIO Conference, 2005Conference paper (Other academic)
  • 39.
    Edström, Kristina
    et al.
    KTH, School of Education and Communication in Engineering Science (ECE), Lärande.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Kuttenkeuler, Jakob
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Mini Workshop - Designing Project-Based Courses for Learning and Cost-Effective Teaching2011In: 2011 Frontiers In Education Conference (FIE), 2011Conference paper (Refereed)
    Abstract [en]

    This workshop draws on experience in the international collaboration for engineering education reform, called the CDIO Initiative, where project-based learning is a key part of the concept. The purpose of project-based courses in engineering education is to provide environments where students can develop a deeper working knowledge of technical fundamentals together with the complex skills necessary for engineering practice, or in short: where students can become engineers. In this workshop, the learning perspective is emphasized, by identifying trade-offs where there are inherent tensions between learning outcomes and other factors in project-based courses (such as project goal, product performance, technical sophistication, teacher popularity, student satisfaction). A set of principles are derived for enhancing learning and teaching in project-based courses, using concrete examples to illustrate thought-provoking implications. Each principle aims to improve both student learning outcomes and cost-effectiveness of teaching. Together the principles constitute a framework for learning-driven course design. The aim is to challenge assumptions and common practices in project-based courses, and provoke fruitful discussion among participants.

  • 40.
    Eklund, Simon
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    CFD modelling of ski-jump spillway in Stornnforsen2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Traditionally when designing dams and spillways, experiments in physical scale models are conductedin order to determine whether or not the design fulls it purpose, and to identify and avoid undesiredproblems, such as unfavourable ow patterns and unwanted water splatter. Physical models can oftenbe expensive and time consuming to build, and often suer from scale eects that in uence the results.Uniper and Vattenfall have recently done experiments in a physical 1:50 scale model of the dam Stornnforsen,in order to test new solutions for the energy dissipation from the spillways. One of the testedsolutions is a ip bucket at the bottom of the right surface spillway.In this project the same solution is numerically modelled, using the CFD software ANSYS® Fluent®,and the results are compared to those from the experiments. The CFD simulations are done both in fullscale and model scale, in order to identify potential scale eects. The aspects that are compared are theheight and length of the jet from the ip bucket.In addition to the CFD simulations, the height and length are also calculated semi-empirically, usingtwo dierent methods.Altogether the results correspond quite well to the experimental values. Some possible scale eects areobserved, where the jet from the full scale simulation is more dispersed than the jet from the model scalesimulation. The jet trajectory from the full scale simulation is also a bit lower than the jet from theexperiments and model scale simulations.The grid independence for the simulations is not quite satisfactory, and the grid should be rened to getmore reliable results. Due to lack of time and computational power any further grid renement is notdone in this project.

  • 41.
    Ekman, Patrik
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Blomquist, Jens
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Conceptual design of a blue water cruiser based on the Storm Bird2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report describes the process of developing a conceptual design of the Storm Bird, a long distance sailing cruiser. The starting point was a boat designed in the mid nineties by the famous Swedish naval architect Håkan Södergren and the aim with the project is to present an idea as to the renewal of the design in a more modern boat. The new Storm bird was supposed to be a full on blue water cruiser concept, a boat that the presumed owner would not have to change in order to set off on his trip.To get insight in the minds and the needs of long distance sailors an extensive market and customer analysis has been undergone. This together with experience in the design team is a base to the thoughts and the ideas incorporated in this design.The hull design was limited to the existing hull moulds meaning that no changes in the hull shape could be made. An alternative however was the transformation from negative to positive transom which proved a very effective way of making the boat feel bigger.The design and layout have been focused on making an effective, well planned but most of all social yacht. The clear boundary between the inside and outside has been removed thanks to a large opening to the cockpit with big windows and good connection. The cockpit and interior areas have been focused towards each other so as to create one big social area, boundary free.Further on the living quarters, as the rest of the boat, are focused on the main idea of the customer being mainly a cruising couple. Therefore an optimal interior layout with focus on the one master cabin has been developedIn the cockpit, seats are comfortable as well as facing forwards and everyone onboard can follow what is going on through the forward placed navigation central. The wide opening between cockpit and interior makes traditional rope handling impossible. All controls are led aft through a clever arrangement to clutches and winches placed on either side of the cockpit instead of on the deck house. This way all functions are in the right position, close to the helmsman. The ropes are later hidden in boxes to ensure a tangle free cockpit.An intelligent overall solution when it comes to onboard systems has been developed as well. Key words have been weight distribution, serviceability and ease of installation. Stowage space and tank volumes correspond to the yacht’s intended use.The structural design has been carried out focusing on arriving at a realistic weight calculation in order to be able to determine centers of gravity and place equipment and ballast to achieve a working concept. Material and manufacturing techniques have been chosen so as to fit the expertise available at the company.Appendage design has focused on modernizing the underwater body by incorporating a new keel and rudder. The performance of the boat has been increased significantly whilst not making it too extreme for its intended purpose.The finished design concept is believed to be a really attractive choice for a blue water sailor.

  • 42.
    Englund, Jon
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Structural strength of work boatsand high speed crafts with floatingframes2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the usage of floating frames in boats. A floating frame is a transverse frame fittedto the longitudinal stiffener flanges without contact with the shell plating, as opposed to the traditionalfixed frame which is welded to the shell plating with the stiffeners most commonly fitted through cut outsin the frame.To study the floating frame structure in a bigger perspective a finite element analysis is performed on amid ship compartment of an existing 60 m high speed catamaran ferry. The analysis is performed on amodel with scantlings as the original craft but with introduced floating frames. Stresses are analysed withrespect to maximum allowable stress as given in the DNV-rules for HAZ.High stresses are found in the bottom of the frames due to the reduced bending stiffness without effectiveflange from the shell plating. A large deformation in the shell plating relative the transverse frames isfound, creating high stresses in the stiffener webs. This deformation is induced by a large verticaldeformation of the frames.It is concluded that the transverse frames requires an increased stiffness to achieve acceptable stress levels.Possible solutions to increase stiffness are discussed, further studies are required to achieve an acceptablestructure.A design criterion for stiffeners in floating frame constructions is evaluated. The criterion considers theinteraction between a concentrated contact force and a bending moment with the purpose of simplifyingthe design process of stiffeners. The criterion is a combination of design methods from DNV HSLC andEurocode 9.The design criterion is found to give conservative results, although not unreasonably conservative. Thecriterion is suitable for the design of smaller work boats where the scantlings traditionally are not veryoptimized.

  • 43.
    Ericson, Molly
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Lake, Hampus
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    LENGTHENING OF A SPECIALIZED REEFER SHIP: Is it economically viable?2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A lengthening of a specialized reefer ship has been investigated in order to determine if it is economically viable or not. The ship type considered is the Crown class specialized reefer ships, where the Crown Topaz and the Crown Ruby are used as reference ships for this study. In order to determine whether a lengthening is economically viable or not, a conceptual design of the lengthened ship has been done. Costs related to the conversion and income due to the increased cargo capacity are calculated and compared in order to determine when the investment for the conversion reaches break-even.

    The ship is lengthened by an open-top section of 28 m, a lengthening from 152 m to 180 m. This results in an increased displacement of the ship which results in a greater cargo capacity. The extension allows for 108 extra FEU high cube refrigerated containers with a gross weight of 30 tonnes. The open-top section and necessary reinforcements are dimensioned according to the requirements of the Classification Society NKK in order to calculate the added weight and costs for the conversion. The result shows an increase in resistance of about 15% for a cruising speed of 19 knots and loaded to 80% of DWT, which is the most common load case for the reference ship. The fuel consumption thereby increases by 15% for a cruising speed of 19 knots.

    The extra cargo capacity of 108 containers corresponds to an increase in container capacity of 154% and about 31% of the total paying cargo capacity, while the increase in fuel consumption for the main machinery is about 15% for a cruising speed of 19 knots and the extra auxiliary engine contributes to an increase of 40 % in fuel consumption for the auxiliary engines.

    Costs for the conversion and loss due to off-hire time are summarized to 5.025 M. USD. The extra income for the containers is calculated to 7715 USD per day with a freight rate of 2500 USD per container. With the fuel oil price of today of 595 USD/tonne and the increased port tariffs due to the conversion, the investment will reach break-even in 4 years. Even if the fuel oil price increases about 8.7% to 647 USD/tonne the investment will reach break-even after 4½ years in operation. If the ships operates within a trade similar to the Coman-trade and with an income of 3000 USD per container the investment will reach break-even after about 2½ years with a fuel oil price of 595 USD/tonne and 3 years with a fuel oil price of 647 USD/tonne.

    Since the Crown class fleet has an average age of 16 years today, the conversion has to be implemented early to make the investment profitable before the ships are ready to be scrapped.

  • 44.
    Eriksson, Marcus
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Ringman, Patrick
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Launch and recovery systems for unmannedvehicles onboard ships. A study and initialconcepts.2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master’s thesis paper is an exploratory study along with conceptual design of launch and recovery systems(LARS) for unmanned vehicles and RHIB:s, which has been conducted for ThyssenKrupp Marine System AB inKarlskrona, Sweden. Two concepts have been developed, one for aerial vehicles (UAV:s) and one for surfaceand underwater vehicles (USV, RHIB and UUV). The goal when designing the two LARS has been to meet thegrowing demand within the world navies for greater off-board capabilities. The two concepts have been designedto be an integrated solutions on a 90 m long naval ship and based on technology that will be proven in year2015-2020. To meet the goal of using technology that will be proven in year 2015-2020, existing and futurepossible solutions has been evaluated. From the evaluations one technique for each concept was chosen forfurther development.In the development of a LARS for aerial vehicles only fixed wing UAV:s have been considered. The conceptwas made for a reference UAV based on the UAV Shadow 200B, which has a weight of 170 kg. The conceptthat was developed is a parasail lifter that can both launch and recover the reference UAV effectively. In thedevelopment of a system for surface and underwater vehicles only vehicle lengths in the span 1-12 m have beenconsidered. The concept that has been developed is a stern ramp that uses a sled to launch and recover all threevehicle types. The two concepts that has been developed are in an early design state and the papers results shouldtherefore be seen as an estimation of what each system are capable of performing.

  • 45.
    Eriksson, Matilda
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Från pappersvaror över Östersjön till säkerhet i Arktis2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport består av tre delar. Sjöfarten har sammanfattats i en personlig essä, ett roro-fartyg harprojekterats för frakt av pappersvaror på Östersjön och säkerhet vid evakueringar från offshoreplattformari Arktis har undersökts.

    Sjöfarten har och har alltid haft stora fördelar i fråga om en infrastruktur som till stora delar redanexisterar i form av den stora yta havet utgör. Jämfört med andra transportmedel är sjöfarten en miljövänliglösning med hög kapacitet. Allt talar för att trafiken med båtar, som länge varit en världsledande del i denglobala handeln kommer fortsätta vara det även i fortsättningen. Branschen bör dock måna om attfortsätta utvecklas i miljösynpunkt och bli ännu bättre inom just det området.

    Fartyget är ett roro-fartyg med kapacitet för 6720 ton last. Under ett år kan drygt en miljon ton varorfraktas från Sundsvall till antingen Lübeck i Tyskland eller Göteborg på Sveriges Västkust. Fartyget är 174meter långt, har en maximal bredd på 23 meter, ett djupgående på 6,55 meter och marschfart på 15 knop.Dess totala deplacement är knappt 16 500 ton och har en blockkoefficient på 0.62. Kriterier och regelverksåsom minsta fribord, stabilitetskriterier och kursstabilitet uppfylls. Motståndsberäkningar har gjorts ochen propeller har valts, vilken har fem blad samt ett bladareaförhållande på 0,6. En motor som klararuträknat effektbehov har föreslagits, och fartyget har värderats ut miljösynpunkt.

    En litteraturstudie om säkerhet i Arktis har genomförts. Faktorer som identifierats som specielltutmärkande är ett i allt högre grad säsongsbundet istäcke, bristande satellittäckning runt polen och att valav räddnings- och evakueringsfarkost spelar stor roll för sannolikheten för en lyckad operation. Slutsatsenär att varje installation behöver en skräddarsydd evakuerings- och räddningsplan, samt att regelverk föroffshorebranshen i Arktis i dagsläget saknas, och bör skrivas innan verksamhet etableras

  • 46.
    Finn, Tobias
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Hydroelasticity of a large floating windturbine platform2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis dene a limit for when hydroelasticity is necessary to include in an analysis of a large oating semi-submersible wind turbine platform in waves. The thesis also includes a description of how to include hydroelasticity in the design of such a structure.

    A simple analysis studying two two-dimensional beams' hydroelastic behaviour in waves is also conducted, observing resonance, large deformations and stresses in the vicinity of the rst elastic natural frequency.

    Hydroelasticity concerns the combined uid-structure interaction for oating exible structures in waves. In a hydroelastic analysis the uid forces and structural deformations are coupled to account for dynamic and kinematic eects. In this thesis the analysed structure is assumed to be beam-like and Euler beam theory is used. The hydrodynamic forces are determined using a linearised Morison's equation. The hydroelastic response is performed in the frequency domain using a modal analysis and it is modelled in a self-developed model using Matlab.

    Most of the concepts and prototypes of oating wind turbines of today have one turbine installed on a oater and the structure is assumed to be rigid. When modelling a structure as exible, elastic responses is observed around the elastic natural frequencies.

    The analysis has been performed on two beams with dierent lengths and stiness' to observe a hydroelastic behavior: 1) when the rst wet elastic natural frequency is about four times the peak frequency of the sea spectra and 2) when the rst wet elastic natural frequency is almost within the sea spectra.

    It has been found that if the rst wet elastic natural frequency of the structure is higher than about 2-5 times than the wave frequency in regular waves or about ve times the peak frequency, a quasi-static assumption is reliable. If the rst wet elastic natural frequency is less than that, hydroelasticity needs to be considered. The actual limit for a quasi-static/hydroelastic assumption needs to be further investigated.

  • 47.
    Fridström, Johan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Some statistical properties of theambient noise in the Baltic Sea andits relation to passive sonar2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Baltic Sea Information on the Acoustic Soundscape (BIAS) is an European Union financed research project coordinated by FOI. The goal is to determine the soundscape of the Baltic Sea. This study is a part of BIAS and was focused on generating Wenz curves for the Bothnian Sea, which is a part of the Baltic Sea. Wenz curves describe the spectral noise level at different sea states. The investigation of the soundscape was done for both summer and winter conditions when the hydrographical situations differ. Further investigations of the noise dependencies of the natural and anthropogenic sound sources were performed. Wind and ships were dominating in a broad frequency band.The influence of ship noise on the ambient noise is dependent of frequency and distance. Ships within 5 km distance dominates the recorded noise levels and are not part of the ambient noise. At distances longer than 5 km a single ship becomes non-distinguishable and part of the range independent noise floor.Passive sonar ranges were calculated for two different sources. The range was shown to be clearly dependent on the sea state. With an increase of wind speed from sea state 0.5 to 3 the range increased with about 100%.The results of this study will be used in BIAS and in related research projects. It may be used for marine biologics but also for development of sonar and underwater systems.

  • 48.
    Frimodig, Love
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Energy efficiency in rotating equipment2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This paper reports the findings of the first stage of a study on how the efficiency of a centrifugal pump depends on the eccentricity of the impeller (rotor). The geometry of the pump is based on the ERCOFTAC centrifugal pump that has been used to validate computational fluid dynamics software with laboratory measurements. The pump is modelled using the CFD-code Comsol multi physics (tm) in order to get the pressure and velocity field. From the pressure and velocity field the efficiency and output power for the pump is calculated. The energy efficiency of the same pump with different static eccentricities is then compared, showing the effect of eccentricity To validate the CFD-model the velocity and pressure field for the pump is compared to results from another simulation of the same pump and an experiment. The comparison shows that the results are comparable and shows good agreement with experimental data. It is showed that the energy losses of the pump increase with increased static eccentricity of the impeller. The losses at 10% eccentricity are about 0.5% of the produced energy. The main contribution to the losses is the introduced asymmetry, eccentricity, of the pump, which causes an unsteady flow and also increases the total unbalance force on the rotor. It is further noted that rotor-stator interactions of the impeller and the stator blades have small influence on the energy losses. It is concluded that rotordynamic design can improve the energy efficiency of the process that the rotating equipment is involved in. Further research is suggested on whirling eccentric motion, experimental verification and more detailed simulation models.

  • 49.
    Fürth, Mirjam
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Determining the pressure distribution on submerged 2D bodies using dissipative potential flow.2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Globalization is reaching the furthest corners of the world and with globalizations comes a rising demand on transportation. In shipping; a significant cost both to the ship owners and the environment are the fossil fuels used for propulsion, even a small reduction in the wave resistance can bring considerable reductions both in operating costs and emissions for such ships. When designing a ship it is important to be able to make fast and accurate predictions of its resistance so that more efficient hull forms can be selected early in the design process. A panel method based on potential flow is a fast scheme to determine the wave resistance and is therefore suitable to be used early on in the design process. Here it is shown that potential flow can be improved by including Rayleigh damping, added viscous effects that will make the flow dissipative. Dissipative Green functions are employed in the proposed technique with the resulting velocity potential determined from a combination of a source distribution and a modified distribution of vortices on submerged 2D bodies. NACA hydrofoils, Joukowski hydrofoils and cylinders are used to test the model. The pressure distribution is more in line with experimental results than previous numerical methods without added viscosity for the NACA hydrofoils. The surface profile has very good comparison with existing numerical results for a NACA hydrofoil in subcritical speeds. However the results are very poor for the Joukowski hydrofoil. There is therefore reason to develop this method further in both 2D and 3D.

  • 50.
    Garme, Karl
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
    Time-Domain Simulations and Measurements of Loads and Motions of Planning High-Speed Craft in Waves2001In: 8th International Symposium on Practical Design of Ships, 2001Conference paper (Other academic)
1234 1 - 50 of 176
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf