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  • 1.
    Andersson, Jennie
    et al.
    Chalmers University of Technology, Sweden.
    Shiri, Alex
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Yixing, Jin
    China Ship Scientific Research Center, China.
    Chengsheng, Wu
    China Ship Scientific Research Center, China.
    Gengyao, Qiu
    China Ship Scientific Research Center, China.
    Deng, Ganbo
    Ecole Centrale de Nantes, France.
    Queutey, Patrick
    Ecole Centrale de Nantes, France.
    Xing-Kaeding, Yan
    Hamburg Ship Model Basin, Germany.
    Horn, Peter
    Hamburg Ship Model Basin, Germany.
    Lücke, Thomas
    Hamburg Ship Model Basin, Germany.
    Kobayashi, Hiroshi
    National Maritime Research Institute, Japan.
    Ohashi, Kunihide
    National Maritime Research Institute, Japan.
    Sakamoto, Nobuaki
    National Maritime Research Institute, Japan.
    Yang, Fan
    Shanghai Ship and Shipping Research Institute, Chia.
    Gao, Yuling
    Shanghai Ship and Shipping Research Institute, China.
    Windén, Björn
    SHORTCUt CFD, USA.
    Meyerson, Max
    University of Michigan, USA.
    Maki, Kevin
    University of Michigan, USA.
    Turnock, Stephen
    University of Southampton, UK.
    Hudson, Dominic
    University of Southampton, UK.
    Banks, Joseph
    University of Southampton, UK.
    Terziev, Momchil
    University of Strathclyde, UK.
    Tezdogan, Tahsin
    University of Strathclyde, UK.
    Vesting, Florian
    Volupe AB, Sweden.
    Hino, Takanori
    Yokohama National University, Japan.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Ship-scale CFD benchmark study of a pre-swirl duct on KVLCC22022In: Applied Ocean Research, ISSN 0141-1187, E-ISSN 1879-1549, Vol. 123, article id 103134Article in journal (Refereed)
    Abstract [en]

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

  • 2.
    Gerhardt, Frederik
    et al.
    SSPA Sweden AB, Sweden.
    Kjellberg, Martin
    SSPA Sweden AB, Sweden.
    Wigren, I
    SSPA Sweden AB, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    Razola, M
    Wallenius Marine, Sweden.
    THE HORNS OF THE TRILEMMA: SEAKEEPING MODEL TESTS FOR A WIND POWERED VESSEL2021Conference paper (Refereed)
    Abstract [en]

    Assessing seakeeping performance at an early stage is even more important for wind powered vesselsthan for conventional ships, since there is little design experience to lean on. When the driving force comes from sails instead of a propeller, ship dynamics change considerably. Course keeping, turning ability, motions and acceleration in waves are just some of the properties that must be assessed. Including wind propulsion devices in a model test is however not straight forward. In this paper we present a methodology for model testing wind powered vessels. Rpm and azimuth-controlled fans/airscrews are used to mimic the aerodynamic forces from the sails. Results from model tests with a car carrier are presented and discussed while particular attention is paid to possible improvements of the test methodology.

  • 3.
    Gerhardt, Frederik
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Hörteborn, Axel
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Lundbäck, Olov
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Nisbet, J
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Olsson, Tobias
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    HORSES FOR COURSES: HOW TO SELECT THE “RIGHT” WIND PROPULSION SYSTEM AND HOW TO MAKE THE BUSINESS CASE2021Conference paper (Other academic)
    Abstract [en]

    Wind propulsion systems (WPS) are major investments and the decision to install them requires careful consideration of many complex questions. In this paper we present a systematic, scientific methodology to assess the benefits and drawbacks of such systems at the early concept stage of a vessel. The purpose is to provide guidance for shipowners and operators and help them make informed decisions. The proposed method was developed into a Software tool called ‘SEAMAN Winds’ and has been correlated to full scale results. The program draws on our large database of model tests, and CFD of hulls and wind propulsion technologies. It uses the intended trading routes of the vessel as an important input, typical output data are: a) performance values (ship speed, power requirements etc.) b) environmental parameters (CO2 avoided, EEDI and EEXI reduction, carbon intensity indicator) c) financial metrics (bunker savings, payback time for installation of WPS) Potential applications of the method include making the business case for one particular WPS or investigating in how far certain systems are more suited for a specific route than others.

  • 4.
    Gerhardt, Frederik
    et al.
    SSPA Sweden AB, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    Li, Da-Qing
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. SSPA Sweden AB, Sweden.
    Malmek, Karolina
    SSPA Sweden AB, Sweden.
    Levelling the Playing Field: A Numerical Platform for the Fair Comparison of Wind Propulsion Systems2022Conference paper (Other academic)
    Abstract [en]

    Wind propulsion systems (WPS) are major investments and the decision to install them requires careful consideration of many complex questions. One of the recurring and challenging issues for ship owners is the choice of a suitable WPS for a specific ship and a specific operational pattern. Today most WPS providers offer on-demand case studies, but obviously the underlying performance prediction methodologies differ from provider to provider. This makes comparing different technologies from competing suppliers next to impossible. In this paper we present a numerical platform to compare different WPS of different makes, sizes, and costs in a fair way. The fundamental idea is to use aerodynamic WPS datasets that are independently verified by SSPA through wind tunnel test, sea trials or extensive CFD. This is combined with a hydrodynamic dataset from SSPAs database of tank tests. The same performance prediction method, identical routes and weather statistics are then used to determine Key Performance Indicators and financial metrics of the competing wind propulsion technologies. The purpose is to provide guidance for shipowners at the early concept stage of a vessel and help them select a system that suits their particular requirements.

  • 5.
    Gypa, Ioli
    et al.
    Chalmers Tekniska Högskola, Sweden.
    Jansson, Marcus
    Kongsberg Maritime Sweden AB, Sweden.
    Gustafsson, Robert
    Kongsberg Maritime Sweden AB, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers Tekniska Högskola, Sweden.
    Controllable-pitch propeller design process for a wind-powered car-carrier optimising for total energy consumption2023In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 269, article id 113426Article in journal (Refereed)
    Abstract [en]

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

  • 6.
    Gypa, Ioli
    et al.
    Chalmers University of Technology, Sweden.
    Jansson, Marcus
    Kongsberg Maritime Sweden AB, Sweden.
    Gustafsson, Robert
    Kongsberg Maritime Sweden AB, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Propeller design procedure for a wind-assisted KVLCC22022In: PRADS 2022 Book of Abstracts, 2022Conference paper (Refereed)
    Abstract [en]

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

  • 7.
    Kim, Keunjae
    et al.
    SSPA Sweden AB, Sweden.
    Leer-Andersen, Michael
    SSPA Sweden AB, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    A STUDY ON THE EFFECT OF HULL SURFACE TREATMENTS on SHIP PERFORMANCES2021Conference paper (Other academic)
    Abstract [en]

    This paper presents a numerical analysis on the induced relation between hull surface roughness and ship performance and discuss how to maintain hull-surface with cost and environmental impact in mind. The analysis is based on CFD simulation of the ship performance due to change of hull surface roughness condition before/after dry-docking and in-water hull cleaning. A typical tanker ship, KVLCC2 is investigated for 14 different partial cleaning cases. The attainable reduction of propulsive power by hull surface treatment is estimated as an index, Cleaning Efficiency Index (CEI). A clear understanding is obtained how hull geometry has profound implication for the effect of roughness on the change of power. Partial hull cleaning of fore-end and stern-aft part of the hull was found to give higher relative CEI than entire hull cleaning. The present study provides guidelines which part of the hull to treat during dry-docking and hull cleaning process with better quality or higher priority if necessary

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  • 8.
    Kim, Keunjae
    et al.
    SSPA Sweden AB, Sweden.
    Leer-Andersen, Michael
    SSPA Sweden AB, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    Hydrodynamic Design of Propulsion Devices taking into ac-count Full Scale Roughness Effects2020Conference paper (Other academic)
    Abstract [en]

    This paper addresses the effects of hull roughness on pro-pulsion performance of ships and demonstrates the importance of taking full scale roughness effects into account when designing propulsion devices. The investigation of the hull roughness effect was performed numerically using SHIPFLOW with the built in roughness model based on the assumption that hull surface roughness is uniformly distributed and can be characterized by the equivalent sand roughness. The ship investigated is a SSPA VLCC with three typical energy saving devices (ESDs), which include a duct, a standard pre-swirl stator (PSS) and two SSPA generic ESDs (GKDM and GKDF). As an initial validation study, numerical simulation and model tests were carried out for the bare hull with two surface conditions: smooth and rough surface. The results from numerical simulation were validated against towing tank tests and clearly indicates a gradual change of flow characteristics/propulsion performances with hull roughness growth: thickening of boundary layer, increase of resistance and propulsion properties (T, Q and RPM). Following the model scale study, full scale simulations have been performed. The results from full scale simulations confirm the trend in increase of EHP and DHP as roughness grows, but even much faster in full scale compared to model scale.   This paper will further focus on combined hull roughness and scale effects in the design of propeller/ESD and prediction of the performance of a ship. A quite interesting finding is that the roughness is not always affecting in negative direction. The propeller can be operating in more favorable conditions with higher angle of attack due to the thickening of the boundary layer with the increase of hull roughness. This can directly lead to the improvement of propulsive efficiency and in turn result in further power reduction with the use of ESDs.      This paper will discuss additional steps needed to take into account of hull roughness in design optimization process of propeller and ESDs and present design methodology for the successful development of propellers and ESDs performing well in actual operational conditions.

  • 9.
    Kim, Keunjae
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Leer-Andersen, Michael
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Roughness Effects on Ship Design and Operation2021In: Part of the Lecture Notes in Civil Engineering book series (LNCE, volume 63), Springer Science and Business Media Deutschland GmbH , 2021, p. 186-204Conference paper (Refereed)
    Abstract [en]

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

  • 10.
    Kim, Keunjae
    et al.
    SSPA Sweden AB, Sweden.
    Leer-Andersen, Michael
    SSPA Sweden AB, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. SSPA Sweden AB, Sweden.
    Orych, M.
    FLOWTECH International AB, Sweden.
    Choi, Y.
    Daewoo Shipbuilding and Marine Engineering Co Ltd, South Korea.
    Hydrodynamic optimization of pre-swirl stator by CFD and model testing2013In: International Shipbuilding Progress, ISSN 0020-868X, E-ISSN 1566-2829, Vol. 60, no 1-4, p. 233-276Article in journal (Refereed)
    Abstract [en]

    With environmental concerns becoming one of the most important issues facing the shipping/ship-building industry today, SSPA has witnessed strong demand for the development of energy saving devices (ESD). SSPA anticipates that the demand will be greater to respond to new requirements set by the IMO regulation on energy efficient design index (EEDI). SSPA has been involved in many joint research projects in developing energy saving solutions. Daewoo Shipbuilding and Marine Engineering Co. Ltd. (DSME) has developed several ESDs in cooperation with SSPA, where SSPA has tested most of the ESDs designed by DSME over the last 10 years. The pre-swirl stator (PSS) is a device mounted on the stern boss just upstream of the propeller (see Fig. 6 or Fig. 33). It is designed to generate pre-swirl flow to the propeller in order to gain a favorable interaction with the propeller that improves the propulsive efficiency and results in a power reduction. This paper is a full description of one of the developments of PSS from the early design stage, optimization phase, and confirmation by model tests to validation through sea trial tests. 

  • 11.
    Kjellberg, Martin
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Gerhardt, Frederik
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Sailing in waves: A numerical method for analysis of seakeeping performance and dynamic behavior of a wind powered ship2022In: SNAME 24th Chesapeake Sailing Yacht Symposium, CSYS 2022, Society of Naval Architects and Marine Engineers , 2022Conference paper (Refereed)
    Abstract [en]

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

  • 12.
    Kontos, S
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Lundbäck, Olov
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Kjellberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Wilske, E
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Manoeuvre simulations in design process of wind powered vesselConference paper (Other academic)
    Abstract [en]

    Wind propulsion systems (WPS) are one of the most promising technologies for ship propulsion that can radically reduce greenhouse gas emissions. However, attention must be paid to the additional transversal forces and yaw moments connected to a wind propulsion system, as it can affect the manoeuvring and seakeeping performance of a ship. This paper demonstrates how time-domain simulations can be utilised to assess the manoeuvrability of a wind powered vessel to support the decision making, from the early design stage, all the way to testing the control systems, design of Human Machine Interface (HMI) and developing crew guidelines and training. The manoeuvre simulations are carried out with SSPA’s six degree of freedom inhouse code, SEAMAN-Winds. We present firstly a validation against manoeuvring model tests of a wind powered ship, where the wind propulsion units are represented by pulling fans. VPP calculations, which are commonly used in the early design phase, can predict the rudder angle required to balance the side force and yaw moment from the wind propulsion system. However, such steady-state computations provide no information on how robust this balance is when dynamic effects are present (e.g., wind gusts) and whether the balance can be regained if it has been momentarily lost. Therefore, time-domain simulations are shown to be useful to assess whether a ship can sail safely close to the limits of its VPP polars. Furthermore, it is demonstrated how mariners operating a real-time manoeuvre simulation tool can be utilised to increase the proof-of-concept, assess the HMI design, and for crew training.

  • 13.
    Korkmaz, K. B.
    et al.
    Chalmers University of Technology, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    Bensow, R.
    Chalmers University of Technology, Sweden; SSPA Sweden AB, Sweden.
    Numerical friction lines for CFD based form factor determination2019Conference paper (Refereed)
    Abstract [en]

    In this study, frictional resistance coefficients of an infinitely thin 2D plate have been computed at 14 Reynolds numbers (between log10(Rn) = 6.25 to 9.5) in sets of five geometrically similar structured grids in order to perform reliable grid dependence studies. Additional grid dependency studies have been performed by using 5 sets of grids which have the same number of cells in all directions but varying first cell sizes normal to the flat plate at log10(Rn) = 6.25. Average y+ values for each grid set for the finest grid varies between 0.0075 and 0.5 (from set 1 to 5 respectively) while none of the simulations exceeded average y+ value of 1. All simulations were performed with the direct application of the no-slip condition at walls. Therefore, no wall functions were used. Two turbulence models have been used for the investigations: k - ? SST and EASM. Extensive grid dependence studies have been performed with two different CFD codes SHIPFLOW and FINE™/MARINE, using the same grids. Special attention was paid to the transition from laminar to turbulent flow at the lowest Reynolds number since laminar part can cover a significant part of the plate. At log10(Rn) = 6.25 for both CFD codes, laminar flow and transition to turbulent flow was distinctive even though no transition models were applied. Significant dependency on y+ has been observed with FINE™/MARINE on friction resistance coefficient. On the other hand, SHIPFLOW exhibited less sensitivity to the first cell size variation, hence, revealed smaller numerical uncertainties in general. To ensure a numerical uncertainty of frictional resistance component below 1%, average y+ < 0.016 have been used for generating the data points of friction line with SHIPFLOW for each turbulence model. Data points of 14 Reynolds number have been transformed into numerical friction lines by applying curve fits. Obtained friction lines are compared with ITTC57 line, Schoenherr, Hughes, Toki, Katsui, Grigson lines and two numerical friction lines.

  • 14.
    Korkmaz, Kadir Burak
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Kim, Keunjae
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Liefvendahl, Mattias
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Orych, Michal
    FLOWTECH International AB, Sweden.
    A Validation Study of Full-Scale CFD Simulation for Sea Trial Performance Prediction of Ships2023Conference paper (Refereed)
    Abstract [en]

    Shipping is a critical component of global trade but also accounts for a substantial portion of global greenhouse gas emissions. Recognising this issue, the International Maritime Organisation (IMO) has implemented new measures aimed at determining the energy efficiency of all ships and promoting continuous improvements, such as the Energy Efficiency Existing Ship Index (EEXI). As Computational Fluid Dynamics (CFD) can be used to calculate the EEXI value, RISE-SSPA1 and Flowtech have developed a CFD-based method for predicting full-scale ship performance with SHIPFLOW v7.0, which meets the new requirements of IMO. The method is validated through an extensive comparison study that examines the delivered power and propeller rotation rate between full-scale CFD predictions and high-quality sea trials using 14 common cargo ships of varying sizes and types. The comparison between the CFD predictions and 59 sea trials shows that both delivered power and RPM can be predicted with satisfactory accuracy, with an average comparison error of about 4% and 2%, respectively. The numerical methods used in this study differ significantly from the majority of the state-of-the-art CFD codes, highlighting their potential for future applications in ship performance prediction. Thorough validation with a large number of sea trials is essential to establish confidence in CFD-based ship performance prediction methods, which is crucial for the credibility of the EEXI framework and its potential to contribute to shipping decarbonisation.

  • 15.
    Korkmaz, Kadir Burak
    et al.
    Chalmers University of Technology, Sweden; SSPA Sweden AB, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Investigations for CFD Based Form Factor Methods2019Conference paper (Other academic)
    Abstract [en]

    In this study, the form factor concept has been investigated by analyzing the results obtained from the simulations performed on KVLCC2 and KCS hulls. Grid dependence studies, sensitivity analysis of loading conditions and varying grid setups have been performed with SHIPFLOW code. Extrapolation of viscous resistance to full scale has been performed with ITTC57 line and numerical friction lines.

  • 16.
    Korkmaz, Kadir Burak
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Investigations on experimental and computational trim optimisation methods2023In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 288, article id 116098Article in journal (Refereed)
    Abstract [en]

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

  • 17.
    Korkmaz, Kadir Burak
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Scaling of wetted-transom resistance for improved full-scale ship performance predictions2022In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 266, article id 112590Article in journal (Refereed)
    Abstract [en]

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

  • 18.
    Korkmaz, Kadir Burak
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Verification and validation of CFD based form factors as a combined CFD/EFD method2021In: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 9, no 1, article id 75Article in journal (Refereed)
    Abstract [en]

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

  • 19.
    Korkmaz, Kadir Burak
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Sakamoto, Nobuaki
    National Maritime Research Institute, Japan.
    Queutey, Patrick
    Ecole Centrale de Nantes, France.
    Deng, Ganbo
    Ecole Centrale de Nantes, France.
    Yuling, Gao
    Shanghai Ship and Shipping Research Institute, China.
    Guoxiang, Dong
    Shanghai Ship and Shipping Research Institute, China.
    Maki, Kevin
    University of Michigan, USA.
    Ye, Hauxian
    University of Michigan, USA.
    Akinturk, Ayhan
    Ocean Coastal and River Engineering, Canada.
    Sayeed, Tanvir
    Ocean Coastal and River Engineering, Canada.
    Hino, Takanori
    Yokohama National University, Japan.
    Zhao, Feng
    China Ship Scientific Research Centre, China.
    Tezdogan, Tahsin
    University of Strathclyde, UK.
    Demirel, Yigit
    University of Strathclyde, UK.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    CFD based form factor determination method2021In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 220, article id 108451Article in journal (Refereed)
    Abstract [en]

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

  • 20.
    Li, D-Q
    et al.
    SSPA Sweden AB, Sweden.
    Lindell, P
    SSPA Sweden AB, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    Transitional flow on model propellers and their influence on relative rotative efficiency2019In: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 7, no 12Article in journal (Refereed)
    Abstract [en]

    Unexpected low value of the relative rotative efficiency ηR is sometimes noted when scaling the towing tank model-test result with the ITTC-78 method to obtain the propulsive efficiency factors of propellers. The paper explains the causes of this phenomenon. The boundary layer state of three propellers was studied by a paint test and a RANS method. The paint tests showed that the propellers in behind conditions at low Reynolds number (Rn) are covered mainly with laminar flow, which is different from open water tests conducted at a high Rn. Apart from that a moderate difference in Rn between the open water and the self-propulsion test may lead to a low ηR value, the paper points out that flow separation in behind conditions could be another significant reason for the drop of ηR for some propellers. Therefore, two factors will lead to an unexpected decrease of ηR: (1) A slightly lower open water torque interpolated from an open water test carried out at a high Rn and (2) a slightly higher torque in a self-propulsion test due to laminar flow separation near the trailing edge. The phenomenon is caused by the Rn scaled effect and closely associated with design philosophy like the blade section profile, the chord length, and chordwise load distribution. 

  • 21.
    Malmek, Karolina
    et al.
    SSPA Sweden AB, Sweden; Chalmers University of Technology, Sweden.
    Dhomé, Ulysse
    KTH Royal Institute of Technology, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Finnsgård, Christian
    SSPA Sweden AB, Sweden.
    Comparison of two rapid numerical methods for predicting the performance of multiple rigid wing-sails2020Conference paper (Other academic)
    Abstract [en]

    The purpose of this study is to compare the accuracy of two cost-effective aerodynamic methods used to predict the performance of a large scale wind propulsion system. The methods are evaluated regarding their ability to predict the performance of a configuration consisting of four rigid wing sails of an approximate height of 80 m and average chord length of 23 m. The distance between the wing sails, from trailing to leading edge, is about one chord length. For a limited number of test cases, it is evaluated how well the methods balance computational cost and accuracy and their potential to predict the performance of multiple rigid wing configurations. Two different types of aerodynamic methods are compared; one method under development based on potential flow/lifting line theory in combination with pre-calculated 2D CFD RANS data (CORR-SILL), and a vortex lattice method (VLM). The results from the two different methods are compared with 3D CFD RANS simulations. The parameters compared are the induced velocities around the sails, system forces and longitudinal center of effort. This paper indicates that both evaluated methods show potential to predict the magnitude and distribution of the forces on multiple wing sail, with a large reduction of computational effort compared to CFD.

  • 22.
    Malmek, Karolina
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Bensow, Rickard
    Chalmers University of Technology, Sweden.
    Finnsgård, Christian
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Rapid aerodynamic method for predicting the performance of interacting wing sails2024In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 293Article in journal (Refereed)
    Abstract [en]

    Rapid performance prediction tools are required for the evaluation, optimization, and comparison of different wind propulsion systems (WPSs). These tools should capture viscous aerodynamic flow effects in 3D, particularly the maximum propulsion force, stall angles, and interaction effects between the lift-generating units. This paper presents a rapid aerodynamic calculation method for wing sails that combines a semi-empirical lifting line model with a potential flow-based interaction model to account for 3D interaction effects. The method was applied to a WPS that consisted of several wing sails with considerable interaction effects. The results were compared to CFD RANS simulations in 2D and in 3D. For the evaluated validation cases, the interaction model improved the prediction considerably compared to when the interaction was not accounted for. The method provided acceptable driving force, moments, and stall predictions, with negligible computational cost compared to 3D CFD simulations. 

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  • 23.
    Marimon Giovannetti, Laura
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Alexandersson, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Olsson, F
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    APPENDAGES INVESTIGATION AND THEIR EFFECTS ON MANEUVERING COEFFICIENTS FOR APPLICATIONS IN WIND ASSISTED SHIPS2020Conference paper (Refereed)
    Abstract [en]

    When designing a hull that needs to account for sails, either rigid or flexible, it is necessary to consider the larger leeway and heel angles deriving from the sails side-forces compared to a traditional ship. It is therefore necessary to explore the possibility of adding appendages to the hull to balance those forces, achieving an optimum trade-off between hydrodynamic efficiency and manoeuvrability. The possibility of numerically simulating the manoeuvre coefficients at design stage will increase the chances of understanding the behaviour of a ship from an early stage in the design process. The current research is based on the evaluation of hydrodynamic efficiency and manoeuvre coefficients of a hull with rudders and shafts in a pure resistance, self-propulsion and in a wind-assisted mode. Having assessed the performances of the vessel with a Velocity Prediction Program (VPP), an in-depth research on suitable appendages was performed to reduce the experienced leeway angle, and ultimately increase the performances of a wind-assisted ship, especially when subject to wind angles ranging between 40 and 80. Many CFD simulations were initially performed to assess the hydrodynamic characteristics of the hull in a range of flow directions, rudder angles, ship speed and combinations. Those simulations encompass the whole range of datapoint needed to describe the forces and moments acting on a wind-assisted ship, simulating a towing-tank captive test, namely performing a Virtual Captive Test (VCT) [1]. Three types of possible appendages used to increase the generated side-force of the wind-assisted vessel are further investigated and the advantages and disadvantages are described. The findings of those preliminary simulations are then used as a basis for a structured model testing campaign.

  • 24.
    Marimon Giovannetti, Laura
    et al.
    SSPA Sweden AB, Sweden.
    Gerhardt, Frederik
    SSPA Sweden AB, Sweden.
    Kjellberg, Martin
    SSPA Sweden AB, Sweden.
    Alexandersson, Martin
    SSPA Sweden AB, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    The art of model testing: Using CFD to adapt traditional tank testing techniques to a new era of wind propelled shipping2020Conference paper (Refereed)
    Abstract [en]

    Hybrid testing is an experimental technique that can be used to test ships and marine structures when both hydrodynamic and aerodynamic effects are important, for example for wind powered or wind assisted ships and sailing vessels. SSPA is currently developing an experimental method using hybrid testing involving fan forces added to ship decks to simulate sails to assess the course keeping, seakeeping and manoeuvring performance of a wind powered ship. For conventional motor ships there are well established test methods and knowledge on how to scale the results from model to full-scale. For a wind propelled ship however, the driving force is no longer located at the propeller shaft but high above deck and at another longitudinal position that could vary with true wind angle and speed. Moreover, there is a large side force coming from the aerodynamic forces of the wingsails that needs to be counteracted with lifting surfaces underwater. The side-force and yaw moment are much more prominent than in conventional vessels. The combination of those factors will influence the manoeuvrability and course keeping, especially in waves. Having built up the research tools for predicting and simulating the behaviour of a full-scale vessel, making the model sail in a similar way as predicted for the full-scale vessel remains a challenge because of the difference between Froude scaling and Reynolds scaling applicable for the hull and lifting surfaces respectively. Using Computational Fluid Dynamics (CFD) to understand the scale effects in model tests for a wind powered ship and developing a methodology for determining the fan parameters that correctly model the ships behaviour and performance are the key objectives of the research study. The art of model testing encompasses the need to learn from different techniques to ultimately achieve the best agreement between model tests and full-scale results in terms of accuracy, repeatability, cost, and speed. Learning from preliminary experimental tests, through studies on CFD and ultimately paving the way to new testing methodologies is the main aim of the current paper.

  • 25.
    Marimon Giovannetti, Laura
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Ljungqvist, Kasper
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Variation of underwater appendages and their effects on wind powered ships2021In: 7th High Performance Yacht Design Conference, HPYD 2021, The Royal Institution of Naval Architects , 2021Conference paper (Refereed)
    Abstract [en]

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

  • 26.
    Oliveira, D. R.
    et al.
    Chalmers University of Technology, Sweden.
    Lagerström, Maria
    Chalmers University of Technology, Sweden.
    Granhag, Lena
    Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Larsson, Ann I
    University of Gothenburg, Sweden.
    Ytreberg, Erik
    Chalmers University of Technology, Sweden.
    A novel tool for cost and emission reduction related to ship underwater hull maintenance2022In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 356, article id 131882Article in journal (Refereed)
    Abstract [en]

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

  • 27.
    Oliveira, Dinis
    et al.
    Chalmers University of Technology, Sweden.
    Lagerström, Maria
    Chalmers University of Technology, Sweden.
    Granhag, Lena
    Chalmers University of Technology, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    Larsson, Ann I.
    University of Gothenburg, Sweden.
    Ytreberg, Erik
    Chalmers University of Technology, Sweden.
    HullMASTER – An Interactive Tool to Calculate Economic and Societal Costs and Benefits of Ship Hull Maintenance2021Conference paper (Other academic)
    Abstract [en]

    Through cross-disciplinary research a novel interactive tool has been developed, HullMASTER, which enables shipowners, operators, and authorities in the Baltic Sea region to make evidence-based decisions on strategies and policies related to ship hull maintenance. This novel tool is deployed as a standalone app (source code in MATLAB). Modelling is based on cost-effective approximate prediction methods (Granville method), as well as on empirical fouling data. Validation of HullMASTER predictions for hull-and-propeller performance shows ~80% agreement against nearly 40 vessel-years of performance data (fleet of 9 vessels). Further, three types of hull coating were compared in a demonstration case: a copper-based antifouling coating, a biocide-free foul-release coating, and an inert abrasion-resistant coating. In this demonstration, the foul-release coating is shown to be the most sustainable alternative for a 10,000-DWT cargo ship in terms of pressure on the environment and health. These societal savings are aligned with potential economic savings for the shipping operator.

  • 28.
    Olsson, Fredrik
    et al.
    SSPA Sweden AB, Sweden.
    Marimon Giovannetti, Laura
    SSPA Sweden AB, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    Finnsgård, Christian
    SSPA Sweden AB, Sweden.
    A Performance Depowering Investigation for Wind Powered Cargo Ships Along a Route2020In: Journal of Sailing Technology, Vol. 5, no 1, p. 47-Article in journal (Refereed)
    Abstract [en]

    For a sailing yacht, depowering is a set of strategies used to limit the sail force magnitude by intentionally moving away from the point of maximum forward driving force, potentially reducing the ship speed. The reasons for doing this includes among others; reduction of quasi-static heeling angle, structural integrity of masts and sails and crew comfort. For a wind powered cargo ship, time spent on a route is of utmost importance. This leads to the question whether there is a performance difference between different depowering strategies and if so, how large. In this research, a wind-powered cargo vessel with rigid wings is described in a Velocity Prediction Program (VPP) with four-degrees of freedom, namely surge, sway, roll and yaw, with a maximum heel angle constraint. The resulting ship speed performance for different depowering strategies are investigated and the implications in roll and pitch-moments are discussed. The wind conditions when depowering is needed are identified. A statistical analysis on the probability of occurrence of these conditions and the impact of the different depowering strategies on the required number of days for a round-trip on a Transatlantic route is performed.

  • 29.
    Orych, Michal
    et al.
    FLOWTECH International AB, Sweden; Chalmers University of Technology, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Larsson, Lars
    Chalmers University of Technology, Sweden; ISYD AB International School of Yacht Design, Sweden.
    Roughness effect modelling for wall resolved RANS – Comparison of methods for marine hydrodynamics2022In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 266, article id 112778Article in journal (Refereed)
    Abstract [en]

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

  • 30.
    Orych, Michal
    et al.
    Chalmers University of Technology, Sweden; FLOWTECH International AB, Sweden.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Larsson, Lars
    FLOWTECH International AB, Sweden.
    Validation of full-scale delivered power CFD simulations2021In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 238, article id 109654Article in journal (Refereed)
    Abstract [en]

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

  • 31.
    Orych, Michal
    et al.
    Chalmers University of Technology, Sweden; FLOWTECH International AB, Sweden.
    Östberg, Magnus
    FLOWTECH International AB, Sweden.
    Kjellberg, Martin
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Werner, Sofia
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Larsson, Lars
    Chalmers University of Technology, Sweden; ISYD AB International School of Yacht Design, Sweden.
    Speed and delivered power in waves — Predictions with CFD simulations at full scale2023In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 285, article id 115289Article in journal (Refereed)
    Abstract [en]

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

  • 32.
    Persson, Adam
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Li, Da-Qing
    SSPA Sweden AB, Sweden.
    Olsson, Fredrik
    SSPA Sweden AB, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    Dhome, U.
    KTH Royal Institute of Technology, Sweden.
    Performance prediction of wind propulsion systems using 3D CFD and route simulation2019Conference paper (Refereed)
    Abstract [en]

    Accurate performance prediction is necessary when designing/optimising wind propulsion systems (WPS). An independent, trustworthy prediction of the energy-saving potential is also needed to support the ship owner’s decision to invest in new technology. By using weather statistics along with a mathematical model of ship performance, route simulations can estimate the time and power required for transit of a route. Such simulations are commonly used today to optimise the design and operation of conventional ships. The introduction of WPS poses additional challenges for route simulations. WPS performance must be predicted at all points along the route, with wind of differing velocity and direction. The apparent wind will vary vertically (twist), due to the interaction between the ship velocity and the atmospheric boundary layer. Also, many proposed concepts use multiple WPS, introducing additional complexity, such as independent spin ratios/ sheeting angles. 3D CFD simulations capture the complex physics, including vortex formation and interaction effects, providing accurate performance prediction and an understanding of the flow. However, 3D CFD is costly, and it would not be possible to simulate all conditions at a reasonable cost. We present simplified approaches to modelling of WPS, using a limited number of CFD simulations, either in 2D or 3D, which are then extrapolated such that 3D effects are represented, and all conditions covered. The methodology is demonstrated on rotor sails and wing sails.

  • 33.
    Strasser, G.
    et al.
    University of Tokyo, Japan.
    Takagi, K.
    University of Tokyo, Japan.
    Werner, Sofia
    University of Tokyo, Japan.
    Hollenbach, U.
    University of Tokyo, Japan.
    Tanaka, T.
    University of Tokyo, Japan.
    Yamamoto, K.
    University of Tokyo, Japan.
    Hirota, K.
    University of Tokyo, Japan.
    A verification of the ITTC/ISO speed/power trials analysis2015In: Journal of Marine Science and Technology, ISSN 0948-4280, E-ISSN 1437-8213, Vol. 20, no 1, p. 2-13Article in journal (Refereed)
    Abstract [en]

    Speed and power (S/P) trials are most important to guarantee the ship’s propulsive performance. However, it was pointed out that the existing procedures often give a good guideline, but are not specific and can introduce inconsistent results. Recently, ITTC and ISO have improved their S/P trials procedures and harmonized the two procedures. During the harmonization process, we have verified the ‘Mean of Means’ (MoM) method and the ‘Iterative’ method which are used as the current correction methods and the ‘Direct Power Method’ and the ‘Extended Power Method’ which are applied for the evaluation of the acquired data. The results of verification are presented in this paper. The results show that using the ‘MoM’ method for each power setting, two double runs should be made to keep the accuracy of S/P trials, and the ‘Iterative’ method leads to less errors in average of the tested cases when 1 + 2 + 2 double runs are used in the ‘MoM’ method, although the methods are equally adequate if the time periods between the runs are short enough. In specific cases, e.g. in case of large speed range and/or humps and hollows within the speed–power curve, the ‘MoM’ method has advantages over the ‘Iterative’ method. In case of current time history deviating from the assumed parabolic/sinusoidal trend and the change of the current within the time span of two double runs is very high, neither of the methods are applicable. Summarizing the results, the ‘Iterative’ method is fully compatible with the simple ‘Direct Power Method’

  • 34.
    Söder, Carl-Johan
    et al.
    KTH Royal Institute of Technology, Sweden; Wallenius Marine AB, Sweden.
    Rosen, Anders
    KTH Royal Institute of Technology, Sweden.
    Werner, Sofia
    SSPA Sweden AB, Sweden.
    Huss, Mikael
    Wallenius Marine AB, Sweden.
    Kuttenkeuler, Jakob
    KTH Royal Institute of Technology, Sweden.
    Assessment of ship roll damping through full scale and model scale experiments and semi-empirical methods2019In: Fluid Mechanichs and its Application, ISSN 0926-5112, E-ISSN 2215-0056, Vol. 119, p. 177-190Article in journal (Refereed)
    Abstract [en]

    This paper presents unique experimental set-ups in model scale and full scale for evaluating roll damping properties of a Panamax Pure Car and Truck Carrier at speed. The purpose of this study is to develop a method for the assessment of roll damping based on full scale trials and to validate the use of roll damping derived from model tests for full scale vessels. Experimental data are also used to assess a semi-empirical method that today provides input for the prediction of critical rolling events such as parametric rolling and severe rolling motions in general. 

  • 35.
    Werner, Sofia
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. SSPA, Sweden.
    Kuttenkeuler, J.
    KTH Royal Institute of Technology, Sweden.
    Hörteborn, Axel
    SSPA, Sweden.
    Lundbäck, Olov
    SSPA, Sweden.
    Razola, M.
    Wallenius Marine, Sweden.
    Dhome, U.
    KTH Royal Institute of Technology, Sweden.
    Performance predictions of long-distance sailing vessels2021Conference paper (Refereed)
    Abstract [en]

    Designing sailing vessels for world-wide cargo transportation requires that the trade route and weather conditions are taken into consideration in the design process. This work studies various strategies for representing the weather distribution related to the expected operational profile. The balance between accuracy and design work efficiency for the different methods is discussed and demonstrated for a wind powered car carrier concept. © HPYD 2021.All right reserved.

  • 36.
    Werner, Sofia
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. SSPA Sweden AB, Sweden.
    Kuttenkeuler, Jakob
    KTH Royal Institute of Technology, Sweden.
    Hörteborn, Axel
    SSPA Sweden AB, Sweden.
    Lundbäck, Olov
    SSPA Sweden AB, Sweden.
    Razola, Mikael
    Wallenius Marine, Sweden.
    Dhome, U
    KTH Royal Institute of Technology, Sweden.
    ROUTE EVALUATION METHODS FOR LONG-DISTANCE SAILING VESSEL PERFORMANCE PREDICTIONS2021Conference paper (Other academic)
    Abstract [en]

    Designing sailing vessels for world-wide cargo transportation requires that the trade route and weather conditions are taken into consideration in the design process when design candidates are ranked. This work studies various strategies for representing the weather distribution related to the expected operational profile. The simplest approach is to decide on a single wind speed and direction as the design point. A slightly more complex method is to derive a statical distribution of expected weather and weigh the performance at each weather condition with its expected probability. The most demanding methods are route analysis using weather optimisation. The balance between accuracy and design work efficiency for the different methods is discussed and demonstrated for a wind powered car carrier concept. As an example, two design candidates are compared, and it is shown that the ranking differs considerably depending on which route representation strategy is used. To weigh the performance using the probability of the expected weather turns out to be an efficient method that gives similar results as the time demanding complete route optimisation. However, if the EEDI Global weather matrix defined by IMO is used for the weather probability distribution instead of statistics of the actual route, the ranking of the design candidates is rather different.

  • 37.
    Werner, Sofia
    et al.
    Chalmers University of Technology, Sweden.
    Larsson, L.
    Chalmers University of Technology, Sweden.
    Regnström, B.
    Flowtech International AB, Sweden.
    Wind tunnel test of an America’s cup keel - A test case for CFD validation2007In: Transactions of the Royal Institution of Naval Architects Part B: International Journal of Small Craft Technology, ISSN 1740-0694, Vol. 149, no 2, p. 23-33Article in journal (Refereed)
    Abstract [en]

    A wind tunnel test of a winglet keel model is presented. The test includes force measurements as well as a wake survey. Results are reported for several winglet pitch angles and two winglet positions. The measured trends as well as the absolute values of the forces and the wake fields can be used for validating CFD codes. 

  • 38.
    Werner, Sofia
    et al.
    Chalmers University of Technology, Sweden.
    Larsson, L
    Chalmers University of Technology, Sweden.
    Regnström, Björn
    Chalmers University of Technology, Sweden.
    A CFD validation test case-wind tunnel tests of a winglet keel2006Conference paper (Refereed)
    Abstract [en]

    Wind tunnel test results of a winglet keel model are presented. Results including force measurements and wake surveys for several winglet pitch angles and two winglet longitudinal positions are shown. The measured trends as well as the absolute values of the forces and the wake fields can be used for validating CFD codes.

  • 39.
    Werner, Sofia
    et al.
    Chalmers University of Technology, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Regnström, Björn
    Chalmers University of Technology, Sweden.
    CFD validation for a yacht keel2006Conference paper (Other academic)
  • 40.
    Werner, Sofia
    et al.
    Chalmers University of Technology, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Regnström, Björn
    Chalmers University of Technology, Sweden.
    Wake survey of a yacht keel for CFD validation and flow analysis2007In: Schiffstechnik, Vol. 54, p. 28-42Article in journal (Refereed)
    Abstract [en]

    A survey of the wake of a keel/bulb/wing configuration is presented and analysed in detail. It is shown that- Wake measurements can be useful for validation of flow field predictions using RANS- RANS simulations can in turn be used to explain the measured wake fow patterns- Wake measurements can be used to highlight important differences between design alternatives. In the current test case the wake measurements helped to point out the effect of winglets. This effect could also be related to pressure differences on the bulb computed with RANS

  • 41.
    Werner, Sofia
    et al.
    Chalmers University of Technology, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Regnström, Björn
    Chalmers University of Technology, Sweden.
    Wind tunnel test of a winglet keel and how it can be used for CFD validation2005Conference paper (Other academic)
  • 42.
    Werner, Sofia
    et al.
    SSPA Sweden AB, Sweden.
    Nisbet, J
    SSPA Sweden AB, Sweden.
    Hörteborn, Axel
    SSPA Sweden AB, Sweden.
    Nielsen, R
    Scandlines, Denmark.
    PEED TRIAL VERIFICATION FOR A WIND ASSISTED SHIP2021Conference paper (Refereed)
    Abstract [en]

    As the number of wind assistance installations in commercial shipping grows and the industry matures, the need for fullscale verification of the performance increases. Standard procedures or guidelines for conducting such full-scale trials of are still lacking. One strategy is proposed and discussed here. The method is demonstrated using a speed trial conducted with Scandlines’ hybrid ferry Copenhagen equipped with a rotor sail. The trial result is extrapolated to yearly power saving using a statistical route analysis. With this approach, the result can be derived at a feasible cost, within a limited time frame and using commercially available tools and established procedures.

  • 43.
    Werner, Sofia
    et al.
    SSPA Sweden AB, Sweden.
    Nisbet, Jonny
    SSPA Sweden AB, Sweden.
    Olsson, Fredrik
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Sea Trial Methodology for Wind Assisted Ships2022Conference paper (Refereed)
    Abstract [en]

    Wind propulsion technology has the potential to significantly lower the fuel consumption of cargo vessels and improve the EEDI/EEXI. The number of wind propulsion installations is predicted to increase rapidly the coming years, and thereby the number of different technologies and makers. This development calls for standardised procedures for validation of the wind propulsor performance in fullscale. However, such standard procedures or guidelines are still lacking. This paper proposes a methodology based on short sea trials, combined with digital twin modelling and statistical voyage analysis. The method is demonstrated using full scale trials for three cargo vessels with wind assistance technology. Various strategies for conducting as well as analysing the trials are discussed.

  • 44.
    Werner, Sofia
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Papanikolaou, Apostolos
    National Technical University Athens, Greece.
    Razola, Mikael
    Alfawall Oceanbird, Sweden.
    Fagergren, Carl
    Wallenius Marine, Sweden.
    Dessen, Lars
    Wallenius Wilhelmsen Ocean AS, Norway.
    Kuttenkeuler, Jakob
    KTH Royal Institute of Technology, Sweden.
    Santén, Vendela
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    Steinbach, Christoph
    StormGeo, Norway.
    The Orcelle project – Towards Wind-Powered Ships for Deep Sea Cargo Transport2023Conference paper (Refereed)
    Abstract [en]

    International regulations on greenhouse gas (GHG) emissions as well as strong market demand for zero-emission transport calls for a radical change in the shipping industry. Measures such as hull form optimization, use of alternative fuels and efficient machinery systems, new coatings, and smart routing have already improved the energy efficiency of the world fleet and to some extent its GHG emissions. However, it is far from enough. To make the drastic leap that we need in order to meet the climate challenges, we must turn to emission-free energy sources. One such promising and well-proven zero-emission propulsion system for shipping is wind propulsion. Using wind to power cargo vessels restarted on a commercial scale about a decade ago. Currently, there are 25+ wind-assisted vessels in commercial trade. They are equipped with technologies like Flettner rotors, wings or kites, which gives fuel reductions in the magnitude of 1-20 %. Although these are significant fuel savings, this is still not enough to effectively respond to the challenges for zero GHG emissions of the maritime industry. With the goal of demonstrating that even higher energy reduction and drastic reduction of emissions is possible, 11 representatives of the European maritime industry and research community have recently joined forces in the large scale EU-funded project Orcelle, led by Wallenius Wilhelmsen Ocean. The current paper will present the project’s ambition, scope of work and expected outcome. 

  • 45.
    Werner, Sofia
    et al.
    Chalmers University of Technology, Sweden.
    Pistidda, A.
    University of Cagliari, Italy.
    Larsson, L.
    Chalmers University of Technology, Sweden.
    Regnström, Björn
    Chalmers University of Technology, Sweden; Flowtech International, Italy.
    Computational fluid dynamics validation for a fin/bulb/winglet keel configuration2007In: Journal of Ship Research, ISSN 0022-4502, E-ISSN 1542-0604, Vol. 51, no 4, p. 343-358Article in journal (Refereed)
    Abstract [en]

    A wind tunnel test of an America’s Cup keel model is used for validation of one Reynolds-averaged Navier Stokes (RANS) code and one potential flow/boundary layer code. The effects of grid size, stagnation point anomaly, and turbulence model on the RANS results are discussed. Various setups of the potential code are compared. The ability of both methods to predict forces and trends are shown. The errors of the RANS code are slightly larger than the experimental error, whereas the potential flow/boundary layer results are within the experimental uncertainty, provided that a correct panelization is used. A comparison of the experimental wake flow pattern to the one computed with RANS is presented. The k-Ï turbulence model is shown to give the best predictions of the wake.

  • 46.
    Werner, Sofia
    et al.
    Chalmers University of Technology, Sweden.
    Pistidda, Alessio
    University of Cagliari, Italy.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Regnström, Björn
    Chalmers University of Technology, Sweden.
    Computational Fluid Dynamics Validation for a Fin/Bulb/Winglet Keel Configuration2007In: Journal of Ship Research, ISSN 0022-4502, E-ISSN 1542-0604, Vol. 51, no 04, p. 343-356Article in journal (Refereed)
    Abstract [en]

    A wind tunnel test of an America’s Cup keel model is used for validation of one Reynolds-averaged Navier Stokes (RANS) code and one potential flow/boundary layer code. The effects of grid size, stagnation point anomaly, and turbulence model on the RANS results are discussed. Various setups of the potential code are compared. The ability of both methods to predict forces and trends are shown. The errors of the RANS code are slightly larger than the experimental error, whereas the potential flow/boundary layer results are within the experimental uncertainty, provided that a correct panelization is used. A comparison of the experimental wake flow pattern to the one computed with RANS is presented. The k-w turbulence model is shown to give the best predictions of the wake.

  • 47.
    Werner, Sofia
    et al.
    Chalmers University of Technology, Sweden.
    Regnström, Björn
    Chalmers University of Technology, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Adaptive multigrid for the incompressible Navier Stokes equations2003Conference paper (Other academic)
  • 48.
    Werner, Sofia
    et al.
    Chalmers University of Technology, Sweden.
    Regnström, Björn
    Chalmers University of Technology, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Towards a CFD validiation test case – wind tunnel test of a winglet keel2004Conference paper (Other academic)
  • 49.
    Werner, Sofia
    et al.
    Chalmers University of Technology, Sweden.
    Regnström, Björn
    Chalmers University of Technology, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Verification of Navier-Stokes Solutions - a Study Based on an Analytical Test Case2002Conference paper (Other academic)
1 - 49 of 49
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