| 1. |
- Banhegyi, Eliza, et al.
(författare)
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Prediction of Wind Fields using Weather Pattern Recognition : Analysis of Sailing Strategy and Real Weather Data in Tokyo 2020 Olympics
- 2022
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Ingår i: Journal of Sailing Technology. - : The Society of Naval Architects and Marine Engineers. - 2475-370X. ; 7:01, s. 186-202
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Tidskriftsartikel (refereegranskat)abstract
- The Tokyo 2020 Olympic Sailing Competitions were held in Enoshima Bay between the 25th of July and the 4th of August 2021. The climatological and the strategical analysis of the race area for the Swedish Sailing Team was developed in the three years prior to the Olympics (Masino et al., 2021). The result of the three years’ research was a tool named ”Call Book” that provides strategical rules for sailors and coaches both in terms of expected ranges of wind speed and direction and also in terms of trends with explanations for each identified weather pattern. The support team was working not only on the forecast but also on the specific analysis of the weather data in the race areas as measured on the water by the Olympics organizing authorities and monitored through the SAP Analytics website (SAP Sailing Analytics, 2021). Two race areas are herein taken into consideration, namely Enoshima and Zushi, where the Swedish Team athletes sailed most of the races. A statistical meta-analysis on the comparison between the forecast issued using the ”Call Book” and measured data on the race areas is carried out, investigating the specific outcome of the strategy of the races with the forecasted meteorological data.
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| 2. |
- Banks, J., et al.
(författare)
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Assessing Human-Fluid-Structure Interaction for the International Moth
- 2016
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Ingår i: Procedia Engineering. - : Elsevier Ltd. - 1877-7058. ; , s. 311-316
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Konferensbidrag (refereegranskat)abstract
- The International Moth is an ultra-lightweight foiling dinghy class. Foil deflections and dynamic sailor-induced motions are identified as two key areas relating to foiling moth performance that are currently ignored in Velocity Prediction Programs (VPP). The impact of foil deflections is assessed by measuring the tip deflection and twist deformation of a T-foil from an International Moth. The full field deformation due to an applied load is measured using Digital Image Correlation (DIC). The foil's structural properties can then be determined based on the measured structural response. The deformations are then calculated for an estimated steady sailing force distribution on the T-foil and their impact on performance is evaluated. To investigate the impact of dynamic sailor motions a system is developed that allows a sailor's dynamic pose to be captured when out on the water by determining the orientations of key body segments using inertial sensors. It is validated against measured hiking moments and is demonstrated to work out on the water whilst sailing. Both these studies pave the way towards developing a Dynamic VPP for the international Moth, which can include unsteady human and foil interactions.
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| 3. |
- Banks, J., et al.
(författare)
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Assessment of Digital Image Correlation as a method of obtaining deformations of a structure under fluid load
- 2015
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Ingår i: Journal of Fluids and Structures. - : Academic Press. - 0889-9746 .- 1095-8622. ; 58, s. 173-187
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Tidskriftsartikel (refereegranskat)abstract
- Digital Image Correlation (DIC) is employed for the measurement of full-field deformation during fluid-structure interaction experiments in a wind tunnel. The methodology developed for the wind tunnel environment is quantitatively assessed. The static deformation error of the system is shown to be less than 0.8% when applied to a curved aerofoil specimen moved through known displacements using a micrometre. Enclosed camera fairings were shown to be required to minimise error due to wind induced camera vibration under aerodynamic loading. The methodology was demonstrated using a high performance curved foil, from a NACRA F20 sailing catamaran, tested within the University of Southampton RJ Mitchell, 3.5. mx2.4. m, wind tunnel. The aerodynamic forces induced in the wind tunnel are relatively small, compared with typical hydrodynamic loading, resulting in small deformations. The coupled deflection and blade twist is evaluated over the tip region (80-100% Span, measured from the root) for a range of wind speeds and angles of attack. Steady deformations at low angles of attack were shown to be well captured however unsteady deformations at higher angles of attack were observed as an increase in variability due to hardware limitations in the current DIC system. It is concluded that higher DIC sample rates are required to assess unsteady deformations in the future. The full field deformation data reveals limited blade twist for low angles of attack, below the stall angle. For larger angles, however, there is a tendency to reduce the effective angle of attack at the tip of the structure, combined with an unsteady structural response. This capability highlights the benefits of the presented methodology over fixed-point measurements as the three dimensional foil deflections can be assessed over a large tip region. In addition, the methodology demonstrates that very small deformations and twist angles can be resolved.
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| 4. |
- Guida, Pierluigi, et al.
(författare)
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Three-dimensional variations of the Nacra 17 main foil for benchmarking shape optimizations
- 2020
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Optimising a three-dimensional foil is becoming an essential part of the design process of high-performance sailing vessels. With the advent of foiling in the America’s Cup in 2013 and the subsequent interest in foiling, the Olympic committee decided that the NACRA 17, a high-performance catamaran already present in the 2016 Rio Olympics, was to start foiling for the 2020 Tokyo Olympic Games. The objective of this research is to explore the hydrodynamic performance variations of the NACRA 17 Z-foil by means of Computational Fluid Dynamics (CFD) simulations, analysing in detail the current design and the possible improvements that could be made to achieve a better performing boat. Exploring changes in the three-dimensional design leads to the understanding that small foil modifications provide similar or higher performances than the current design without affecting the functional requirements of the NACRA 17 class such as the general deck layout. Because small local changes in foil shape could have a large effect on performance, foil design optimization is especially effective for large numbers of shape variables [1]. Despite considerable research on aerodynamic and hydrodynamic shape optimization, there is no standard benchmark problem allowing researchers to compare results. The presented research addresses this issue by running a series of CFD simulations in order to compare the performances of different three-dimensional shapes and configuration arrangements.
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| 5. |
- Knudsen, Stig, et al.
(författare)
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Dynamic Fluid Structure Interaction of NACRA 17 Foil
- 2024
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Ingår i: Journal of Marine Science and Engineering. - 2077-1312. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- The NACRA 17 is a small foiling catamaran that is lifted out of the water by two asymmetric z-foils and two rudder elevators. This paper investigates how foil deflection affects not only foil performance but overall boat behaviour using a numerical Fluid Structure Interaction (FSI) model. The deformations are solved with a solid model based on the Finite Element Method (FEM) and the flow is solved with a Reynolds Average Navier-Stokes (RANS) based Finite Volume Model (FVM). The models are strongly coupled to allow dynamic FSI simulations. The numerical model is validated by comparing it to an experimental campaign conducted at the RISE SSPA Maritime Center in Sweden.Validation shows reasonable agreement, but the model can only be considered validated for some rake angles. The large deformation of the foils is found to have a profound effect on the performance of the foils and therefore of the overall catamaran. Turbulence transition and boat speed are found to affect foil forces and, in turn, deformation. Dynamic response of the foils during boat motion as exposed to waves is investigated and finally the full boat hydrodynamic is simulated by including both foils and the rudders in various scenarios.
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| 6. |
- Lidke, AK, et al.
(författare)
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Development of an America's Cup 45 tacking simulator
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper describes the development of an AC45 simulator conducted as a student Master’s project at the University of Southampton. The main aim was to be able to asses and improve the tacking skills of the helm and the crew through systematic training. The physical interface of the simulator replicates the seating position of the helmsman and the main trimmer and the graphical representation provides the users with visual cues of the simulated boat, boundaries and marks for a sample race course. The theoretical model uses hydrodynamic manoeuvring coefficients based on empirical formulae and experimental data. The aerodynamic forces are pre-calculated using a full-scale RANS CFD simulation. The accuracy of the model is verified against the AC45 racing tracking data to ensure that the speed loss during a tack, experienced by the users of the simulator, is as close to reality as possible. The ultimate aim of the project was to study the potential of the simulator to assess and train the crews, improving their skill in tacking the boat effectively. This has been done by examining the performance of two groups of users over a series of practice sessions. The simulator could be potentially used for training the helmsmen of the Youth America’s Cup Red-Bull teams, which have limited budgets, training days and sailing experience compared to the professional AC sailors.
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| 7. |
- Lidstrom, D, et al.
(författare)
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Agent based match racing simulations : Starting practice
- 2022
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Ingår i: SNAME 24th Chesapeake Sailing Yacht Symposium, CSYS 2022. - : Society of Naval Architects and Marine Engineers.
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Konferensbidrag (refereegranskat)abstract
- Match racing starts in sailing are strategically complex and of great importance for the outcome of a race. With the return of the America's Cup to upwind starts and the World Match Racing Tour attracting young and development sailors, the tactical skills necessary to master the starts could be trained and learned by means of computer simulations to assess a large range of approaches to the starting box. This project used game theory to model the start of a match race, intending to develop and study strategies using Monte-Carlo tree search to estimate the utility of a player's potential moves throughout a race. Strategies that utilised the utility estimated in different ways were defined and tested against each other through means of simulation and with an expert advice on match racing start strategy from a sailor's perspective. The results show that the strategies that put greater emphasis on what the opponent might do, perform better than those that did not. It is concluded that Monte-Carlo tree search can provide a basis for decision making in match races and that it has potential for further use.
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| 8. |
- Marimon Giovannetti, Laura, et al.
(författare)
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APPENDAGES INVESTIGATION AND THEIR EFFECTS ON MANEUVERING COEFFICIENTS FOR APPLICATIONS IN WIND ASSISTED SHIPS
- 2020
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 9. |
- Marimon Giovannetti, Laura, et al.
(författare)
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Developing fluid structure interaction experimental methodologies For dynamic foil measurements
- 2020
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The ability to validate computational predictions of either passive adaptive or dynamic response of deformable foils is essential when seeking to optimise high performance yachts. This requires time-accurate and synchronised measurements of the flow field and the shape of the deformable foil. It is important to understand the accuracy with which the onset of dynamic effects such as flutter or stall can influence the structural design and planform. Examples of such design challenges are present in the design of hydrofoils, wing sails and other propulsion systems such as composite propellers. The current research aims to demonstrate the capability of an experimental methodology that can be used as a validation for numerical investigations of dynamic fluid-structure interaction problems. The presented methodology provides high-speed full-field experimental data of: the structural deformations, by means of Digital Image Correlation (DIC), the tip vortex flow field, by means of Particle Image Velocimetry (PIV) and the forces and moments acting on a flexible aerofoil. A comparison between static and dynamic lift coefficients is presented for unsteady dataset and the effect of dynamic loads are analysed both at structural deformation and flow features level. Overall it is found that it is possible to capture synchronised structural deformation and flow field data at reasonable data rates that allow validation assessment of unsteady CFD.
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| 10. |
- Marimon Giovannetti, Laura, et al.
(författare)
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Developing tools for assessing the fluid structure interaction of passive adaptive composite foils
- 2016
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Ingår i: Insights and Innovations in Structural Engineering, Mechanics and Computation - Proceedings of the 6th International Conference on Structural Engineering, Mechanics and Computation, SEMC 2016. - Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742 : CRC Press/Balkema. - 9781138029279 ; , s. 586-591
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Konferensbidrag (refereegranskat)abstract
- The study presents an experimental and numerical evaluation of bend-twist elastic coupling in composite passive-adaptive structures. Due to the lack of experimental validation in Fluid Structure Interaction (FSI) investigations, a full-field deformation of an aerofoil-shaped section under wind loading is measured. The experimental analysis is carried out at the University of Southampton 3.5 m × 2.4 m R. J. Mitchell wind tunnel using full-field non-contact measurement techniques such as high speed three dimensional Digital Image Correlation (DIC) and stereoscopic Particle Image Velocimetry (PIV). After assessing the validity and repeatability of the experiments, the study focuses on the development of a numerical FSI investigation that involves the use of a structural and a fluid solver to simulate the aero-elastic behaviour of composite tailored structures with different lay-up arrangements. The numerical analysis is developed as a design tool to allow the structure investigated to maximise bend-twist coupling under increased aerodynamic loading.
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