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  • 1. Andersson, A
    et al.
    Barreng, A
    Bohnsack, E
    Lundin, L
    Sahlberg, R
    Werner, E
    Larsson, Lars
    Finnsgård, Christian
    SSPA Sweden AB, Sweden.
    Persson, Adam
    Brown, Matz
    McVeagh, John
    The Foiling Optimist2017Conference paper (Other academic)
  • 2.
    Andersson, Anton
    et al.
    Chalmers University of Technology, Sweden.
    Barreng, Anton
    Chalmers University of Technology, Sweden.
    Bohnsack, Erik
    Chalmers University of Technology, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Lundin, Linus
    Chalmers University of Technology, Sweden.
    Olander, Gustav
    Chalmers University of Technology, Sweden.
    Sahlberg, Robert
    Chalmers University of Technology, Sweden.
    Werner, Erik
    Chalmers University of Technology, Sweden.
    Finnsgård, Christian
    Chalmers University of Technology, Sweden; SSPA Sweden AB, Sweden.
    Persson, Adam
    Chalmers University of Technology, Sweden; SSPA Sweden AB, Sweden.
    Brown, Matz
    SSPA Sweden AB, Sweden.
    McVeagh, John
    SSPA Sweden AB, Sweden.
    Design of a Foiling Optimist2018In: Journal of Sailboat Technology, article id 2018-06Article in journal (Other academic)
    Abstract [en]

    Because of the successful application of hydrofoils on the America's Cup catamarans in the past two campaigns the interest in foiling sailing craft has boosted. Foils have been fitted to a large number of yachts with great success, ranging from dinghies to ocean racers. An interesting question is whether one of the slowest racing boats in the world, the Optimist dinghy, can foil, and if so, at what minimum wind speed. The present paper presents a comprehensive design campaign to answer the two questions. The campaign includes a newly developed Velocity Prediction Program (VPP) for foiling/non-foiling conditions, a wind tunnel test of sail aerodynamics, a towing tank test of hull hydrodynamics and a large number of numerical predictions of foil characteristics. An optimum foil configuration is developed and towing tank tested with satisfactory results. The final proof of the concept is a successful on the water test with stable foiling at a speed of 12 knots.

  • 3.
    Persson, Adam
    et al.
    SSPA Sweden AB, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Brown, Matz
    SSPA Sweden AB, Sweden.
    Finnsgård, Christian
    SSPA Sweden AB, Sweden; Chalmers University of Technology, Sweden.
    Performance evaluation and ranking of 7 rudders for the Finn dinghy2018In: Journal of sailing technology, Vol. 3, no 1, p. 1-Article in journal (Other academic)
    Abstract [en]

    As a follow up to the Olympic Games, commercially available Finn dinghy rudders were tested to determine their hydrodynamic performance. Seven rudders were tested, out of the nine different rudder models that were measured for competition at the 2016 Olympic Games, thus representing a large portion of the rudders used by sailors. The remaining two rudder models could not be tested, since they are of semi-custom or custom design or manufacture. Each rudder was tested in seven different conditions, selected to cover a wide range of sailing conditions. The testing revealed considerable differences, both in performance and handling.

  • 4.
    Persson, Adam
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department. Chalmers University of Technology, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Finnsgård, Christian
    RISE Research Institutes of Sweden, Safety and Transport, Maritime department.
    A time-domain model for unsteady upwind sail aerodynamics using the indicial response method2024In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 299, article id 117311Article in journal (Refereed)
    Abstract [en]

    For the design of sailing vessels, the use of Dynamic Velocity Prediction Programs is expanding, as naval architects start to consider the effects of waves and varying wind conditions in order to design faster, safer and more efficient vessels. Many models that predict the unsteady hydrodynamic response are available, but for sail aerodynamics, few models have been presented, and the quasi-steady assumption is instead commonly used. The aim of this paper is to develop a time-domain model for unsteady sail aerodynamics that can handle arbitrary motions and requires only limited input. The proposed model is based on the Indicial Response Method, with specific adaptations to handle the additional complexity of sail aerodynamics. The model’s predictive performance is evaluated against URANS CFD results for several cases of increasing complexity. This includes a 3D upwind sail plan subjected to pitching motion, where comparisons are also made with the common quasi-steady (Q-S) assumption. Compared to this, the proposed model delivers significantly better predictions for the amplitude of lift, thrust and sideforce. However, the drag amplitude is over-predicted by the model, and as a result, there is a significant misprediction of thrust phase. While there is a need to improve the prediction of unsteady drag, this paper shows that the model represents a significant improvement over the Q-S assumption, for unsteady performance prediction on timescales shorter than the wave period.

  • 5.
    Persson, Adam
    et al.
    Chalmers University of Technology, Sweden; SSPA, Sweden.
    Larsson, Lars
    Chalmers University of Technology, Sweden.
    Finnsgård, Christian
    SSPA, Sweden.
    An improved procedure for strongly coupled prediction of sailing yacht performance2020In: Journal of Sailing Technology, Vol. 6, no 1, p. 133-Article in journal (Refereed)
    Abstract [en]

    In this paper, an improved procedure for strongly coupled prediction of sailing yacht performance is developed. The procedure uses 3D RANS CFD to compute the hydrodynamic forces. When coupled to a rigid body motion solver and a sail force model, along with a rudder control algorithm, this allows sailing yacht performance to be predicted within CFD software. The procedure provides faster convergence when compared to previously published methods. The grid motion scheme, partially using overset grid techniques, means that correct alignment between the free surface and the background grid is ensured even at large heel angles. The capabilities are demonstrated with performance predictions for the SYRF 14 m yacht, at one true wind speed, over a range of true wind angles, with one up- and one downwind sailset. The results are compared to predictions from the ORC-VPP for a yacht with similar main particulars.

  • 6.
    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.

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