| 1. |
- Allroth, Jens, 1984, et al.
(författare)
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Sailing Yacht Transom Sterns-a Systematic CFD Investigation
- 2015
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Ingår i: Proceedings, 5th High Performance Yacht Design Conference, Auckland, 8-11 March 2015. - 9781909024373 ; , s. 257-266
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Konferensbidrag (refereegranskat)abstract
- The question adressed in this project is whether modern hull lines with wide, box-shaped transoms, that seem to originate from extreme racing machines, are also beneficial for modern performance cruisers from a hydrodynamic performance point of view. A new 41 ft (12.3 m) hull was designed as an average of contemporary performance hulls in the 40 ft segment. The aft part of the hull was stretched stepwise and cut at constant length overall in order to systematically increase the transom size. Six hull variations with box shaped transoms were created in this way. To investigate the influence of the transom shape, the six hull variants were redesigned with a more rounded transom. The resistance was calculated for all twelve hulls in the upright and heeled conditions at Froude numbers 0.35 and 0.60. The computations were carried out using a Reynolds-Averaged Navier-Stokes (RANS) solver with a Volume of Fluid (VOF) representation of the free surface. The solver was validated against several hulls in the Delft Systematic Yacht Hull Series (DSYHS). Very different optima are found for the low and high speed cases. In an upwind-downwind race the round transoms performed best for the three fastest transom sizes. The fastest hull around the course has an immersed transom area to midship area ratio of 0.16 and it has a rounded shape. It is 1.9 % faster than a more box like transom. Overall the round transoms are faster around the race course.
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| 2. |
- Finnsgård, Christian, 1974, et al.
(författare)
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High Performance Sailing in Olympic Classes - a Research Outlook and Proposed Directions
- 2015
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Ingår i: Proceedings, 5th High Performance Yacht Design Conference, Auckland, 8-11 March 2015. - : Royal Institution of Naval Architects. - 9781909024373 ; , s. 141-149
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Konferensbidrag (refereegranskat)abstract
- The purpose of this paper is to explore research opportunities in Olympic sailing classes. Olympic classes provide high-performance sailing using a diversity of equipment, with the understanding that the equipment, individual athletes, and the knowledge relating to those two factors impacts performance. Thus, the Olympic motto, “Citius, Altius, Fortius” (Latin for “Faster, Higher, Stronger”), governs everyday life for many engineers. During the last few years, Chalmers has supported a project that focuses on the possibilities and challenges for research combined with engineering knowledge in the area of sports. The initiative has generated external funding and gained great acclaim within Chalmers, among staff and students, in the Swedish sports movement, and in large companies, as well as within small and medium sized enterprises. The project focuses on five sports: swimming, equestrian events, floorball, athletics, and sailing. The contribution from this paper describes an outlook identifying eight areas containing research opportunities: sailing dynamics, how to sail in Olympic classes, fluid structure interaction, surface structures, turbulence induction on the rig, equipment in Olympic classes, and applying game theory to sailing.
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| 3. |
- Orych, Michal, 1979, et al.
(författare)
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Hydrodynamic Aspects of Transom Stern Optimisation
- 2015
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Ingår i: Proceedings, 5th High Performance Yacht Design Conference, Auckland, 8-11 March 2015. - 9781909024373 ; , s. 247-256
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Konferensbidrag (refereegranskat)abstract
- In this work an explanation for an optimum transom size is proposed which takes into account the hull shape between the midship and the transom. A systematic stern modification is performed to study the influence of the shape of waterlines and buttocks on the resistance components. The aft body of a hull is designed in a way that gives a possibility to separate the effects of waterline and buttock curvature and to study their effect on the flow. The Froude numbers are chosen to provide information for wetted- as well as dry-transom conditions. To evaluate the performance of the hulls the SHIPFLOW steady state Reynolds Averaged Navier-Stokes (RANS) code with a Volume of Fluid (VOF) surface capturing method is used in combination with the k-ω SST turbulence model. The code was first thoroughly validated for a transom stern hull. The paper focuses on hydrodynamic and hydrostatic resistance components of the transom and of the rest of the hull. Physical explanations are given for the effects of the aft body hull lines. The transom size, waterline curvature and rocker effects are analysed. The results show that the optimum transom size depends on the balance between the hydrostatic and hydrodynamic force components and the explanation for this is also given
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