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Persson, A., Larsson, L. & Finnsgård, C. (2024). A time-domain model for unsteady upwind sail aerodynamics using the indicial response method. Ocean Engineering, 299, Article ID 117311.
Open this publication in new window or tab >>A time-domain model for unsteady upwind sail aerodynamics using the indicial response method
2024 (English)In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 299, article id 117311Article in journal (Refereed) Published
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.

National Category
Mechanical Engineering
Identifiers
urn:nbn:se:ri:diva-73119 (URN)10.1016/j.oceaneng.2024.117311 (DOI)
Funder
Swedish Energy Agency, 022/P2021-00275Swedish Research Council, 2022-06725Swedish Energy Agency, P47469-1
Note

This research was performed in the projects APPSAIL (Accurate Performance Prediction for Sail-Assisted Ships, grant P47469-1) and Multiwind (Multi-fidelity methods for design and evaluation of wind-powered vessels, grant 022/P2021-00275), both funded by the Swedish Energy Agency, Sweden. The computations were enabled by resources provided by the National Academic Infrastructure for Supercomputing in Sweden (NAISS) at National Supercomputer Centre (NSC), PDC Center for High Performance Computing, and Chalmers Centre for Computational Science and Engineering (C3SE), partially funded by the Swedish Research Council, Sweden through grant agreement no. 2022-06725.

Available from: 2024-05-13 Created: 2024-05-13 Last updated: 2024-05-13Bibliographically approved
Persson, A., Larsson, L. & Finnsgård, C. (2020). An improved procedure for strongly coupled prediction of sailing yacht performance. Journal of Sailing Technology, 6(1), 133
Open this publication in new window or tab >>An improved procedure for strongly coupled prediction of sailing yacht performance
2020 (English)In: Journal of Sailing Technology, Vol. 6, no 1, p. 133-Article in journal (Refereed) Published
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.

National Category
Mechanical Engineering
Identifiers
urn:nbn:se:ri:diva-71660 (URN)
Available from: 2024-02-12 Created: 2024-02-12 Last updated: 2024-05-27Bibliographically approved
Persson, A., Li, D.-Q., Olsson, F., Werner, S. & Dhome, U. (2019). Performance prediction of wind propulsion systems using 3D CFD and route simulation. In: : . Paper presented at 6th International Conference on Computational Methods in Marine Engineering, MARINE 2015 ; Conference Date: 15 June 2015 Through 17 June 2015; (pp. 19-30). Royal Institution of Naval Architects
Open this publication in new window or tab >>Performance prediction of wind propulsion systems using 3D CFD and route simulation
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2019 (English)Conference paper, Published 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.

Place, publisher, year, edition, pages
Royal Institution of Naval Architects, 2019
Keywords
Atmospheric boundary layer; Computational fluid dynamics; Energy conservation; Forecasting; Ships; Vortex flow, Accurate performance; Design and operations; Energy saving potential; Interaction effect; Performance prediction; Propulsion system; Ship performance; Vortex formation, Ship propulsion
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:ri:diva-71798 (URN)2-s2.0-85083895263 (Scopus ID)
Conference
6th International Conference on Computational Methods in Marine Engineering, MARINE 2015 ; Conference Date: 15 June 2015 Through 17 June 2015;
Available from: 2024-02-15 Created: 2024-02-15 Last updated: 2024-02-15Bibliographically approved
Andersson, A., Barreng, A., Bohnsack, E., Larsson, L., Lundin, L., Olander, G., . . . McVeagh, J. (2018). Design of a Foiling Optimist. Journal of Sailboat Technology, Article ID 2018-06.
Open this publication in new window or tab >>Design of a Foiling Optimist
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2018 (English)In: Journal of Sailboat Technology, article id 2018-06Article in journal (Other academic) Published
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.

National Category
Mechanical Engineering
Identifiers
urn:nbn:se:ri:diva-71629 (URN)
Available from: 2024-02-12 Created: 2024-02-12 Last updated: 2024-02-12Bibliographically approved
Persson, A., Larsson, L., Brown, M. & Finnsgård, C. (2018). Performance evaluation and ranking of 7 rudders for the Finn dinghy. Journal of sailing technology, 3(1), 1
Open this publication in new window or tab >>Performance evaluation and ranking of 7 rudders for the Finn dinghy
2018 (English)In: Journal of sailing technology, Vol. 3, no 1, p. 1-Article in journal (Other academic) Published
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.

National Category
Mechanical Engineering
Identifiers
urn:nbn:se:ri:diva-71662 (URN)10.5957.jst.2018.04 (DOI)
Available from: 2024-02-12 Created: 2024-02-12 Last updated: 2024-02-12Bibliographically approved
Andersson, A., Barreng, A., Bohnsack, E., Lundin, L., Sahlberg, R., Werner, E., . . . McVeagh, J. (2017). The Foiling Optimist. In: : . Paper presented at Proceedings of the 4th International Conference on Innovation in High Performance Sailing Yachts, Lorient, France, 28-30 June 2017. (pp. 19).
Open this publication in new window or tab >>The Foiling Optimist
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2017 (English)Conference paper, Published paper (Other academic)
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:ri:diva-71630 (URN)
Conference
Proceedings of the 4th International Conference on Innovation in High Performance Sailing Yachts, Lorient, France, 28-30 June 2017.
Available from: 2024-02-12 Created: 2024-02-12 Last updated: 2024-02-13Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-4500-4462

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