https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Fri, 15 May 2026 22:48:24 GMT 2026-05-15T22:48:24Z http://hdl.handle.net/10985/8837 Simulating variable pitch crossflow water turbines: A coupled unsteady ONERA-EDLIN model and streamtube model PAILLARD, Benoît; HAUVILLE, Frederic; ASTOLFI, Jacques Andre This article describes a new method for simulating unsteady hydrodynamics forces and moments on the blades of a crossflow ‘Darrieus’ turbine with active pitch variation. This method is based on the ONERAEDLIN dynamic stall model, coupled with a momentum streamtube model to take into account the turbine interference on the flow. Both models are presented, and compared separately with experimental results for a pitching airfoil for the ONERA-EDLIN model; and for Darrieus turbine for the momentum theory. The model coupling is then detailed and compared with experimental data taken from the open literature [1] The turbine has 2 straight blades with a NACA 0012 section operating in water at a mean chord Reynolds number of 4 104 for tip speed ratio l ¼ 2.5, 5 and 7.5. Good agreement was found for average l ¼ 5, and qualitative agreement could be obtained at low and high l, where dynamic stall effects and interference effects respectively are predominant. This is positive because l ¼ 5 is the closest value from the optimal power production point. Variable pitch is finally introduced in the model and several functions are tested in order to increase efficiency. A maximum increase of 53% on the power coefficient was found to occur with a sinusoidal law. 2012 Elsevier Ltd. All rights reserved. 1. Introduction Tidal turbines are currently the power source that shows the most advantages [2]. No land occupation like a dam, steady predictable power input and output unlike wind turbines, no waste or side effects like fossil or nuclear power plants. These devices can consist of a classic horizontal axis screw-like systems, or crossflow turbines which have many advantages in water [3], such as being independent of the tide direction. Variable pitch crossflow turbines enable a Darrieus system to improve its performance and decrease parasitic forces,mainly responsible for fatigue and systemfailure [4]. They have been studied at IRENAV since 2007 as the SHIVA project. This project of novel tidal turbines deals with three topics,which will be introduced here. Darrieus turbines have been studied extensively during the 70s and 80s, especially by SANDIA organization [5e8]. A reference publication on this topic can be found in [9]. Though almost no Darrieus turbine produced electrical power from wind since early 90s, a renewed interest arose from water turbines because most drawbacks which prevented this system from becoming Tue, 01 Jan 2013 00:00:00 GMT http://hdl.handle.net/10985/8837 2013-01-01T00:00:00Z PAILLARD, Benoît HAUVILLE, Frederic ASTOLFI, Jacques Andre This article describes a new method for simulating unsteady hydrodynamics forces and moments on the blades of a crossflow ‘Darrieus’ turbine with active pitch variation. This method is based on the ONERAEDLIN dynamic stall model, coupled with a momentum streamtube model to take into account the turbine interference on the flow. Both models are presented, and compared separately with experimental results for a pitching airfoil for the ONERA-EDLIN model; and for Darrieus turbine for the momentum theory. The model coupling is then detailed and compared with experimental data taken from the open literature [1] The turbine has 2 straight blades with a NACA 0012 section operating in water at a mean chord Reynolds number of 4 104 for tip speed ratio l ¼ 2.5, 5 and 7.5. Good agreement was found for average l ¼ 5, and qualitative agreement could be obtained at low and high l, where dynamic stall effects and interference effects respectively are predominant. This is positive because l ¼ 5 is the closest value from the optimal power production point. Variable pitch is finally introduced in the model and several functions are tested in order to increase efficiency. A maximum increase of 53% on the power coefficient was found to occur with a sinusoidal law. 2012 Elsevier Ltd. All rights reserved. 1. Introduction Tidal turbines are currently the power source that shows the most advantages [2]. No land occupation like a dam, steady predictable power input and output unlike wind turbines, no waste or side effects like fossil or nuclear power plants. These devices can consist of a classic horizontal axis screw-like systems, or crossflow turbines which have many advantages in water [3], such as being independent of the tide direction. Variable pitch crossflow turbines enable a Darrieus system to improve its performance and decrease parasitic forces,mainly responsible for fatigue and systemfailure [4]. They have been studied at IRENAV since 2007 as the SHIVA project. This project of novel tidal turbines deals with three topics,which will be introduced here. Darrieus turbines have been studied extensively during the 70s and 80s, especially by SANDIA organization [5e8]. A reference publication on this topic can be found in [9]. Though almost no Darrieus turbine produced electrical power from wind since early 90s, a renewed interest arose from water turbines because most drawbacks which prevented this system from becoming http://hdl.handle.net/10985/9621 Modélisation couplée multiphysique d'une hydrolienne RIM-DRIVEN; A multi physical approach for the design of RIM‑DRIVEN Tidal Turbines DROUEN, Laurent; CHARPENTIER, Jean-Frederic; HAUVILLE, Frederic; ASTOLFI, Jacques Andre; SEMAIL, Eric; CLENET, Stephane Le travail présenté concerne le développement d’une méthodologie de conception de systèmes hydroliens innovants de type RIM‑DRIVEN pour la récupération de l’énergie des courants de marée. L’originalité d’un système RIM‑DRIVEN réside dans la structure même de l’hydrolienne, inspirée directement des nouveaux systèmes de propulsion navale, où le rotor et le stator sont placés en périphérie de l’hélice et protégés par une tuyère, l’entrefer étant immergé. Au sein d’une structure de type RIM‑DRIVEN les phénomènes électromécaniques, thermiques et hydrodynamique sont intimement couplés. Du fait du très fort couplage des phénomènes physiques au sein du système, cette méthodologie associe au sein d’un même environnement d’optimisation des modèles électromagnétiques et thermiques spécifiques de la génératrice avec des modèles hydrodynamique des performances de l’hélice et de l’écoulement dans l’entrefer. L’approche proposée est illustrée par une étude de cas qui concerne une machine de 10m de diamètre destinée à être implantée dans le Raz de Sein. Les modèles ont été validés par des résultats issus d’une campagne expérimentale sur un démonstrateur dédié.; This paper deals with the study of an unconventional design of marine tidal turbine where the electrical generator is located in the periphery of the blades and where the magnetic gap is underwater. This kind of solution called “RIM DRIVEN” structure allows increasing the compactness and the robustness of the system. Due to the strong interaction of the multi physical phenomena, an electromagnetic model and a thermal model of the PM generator are associated with a hydrodynamic model of the blades and of the water flow in the underwater air gap. These models are used in a global coupled design approach in order to optimize, under constraints, the global efficiency of the system. This approach is illustrated in a case study which deals with the design of a 10m diameter tidal turbine. Proposed coupled models are validated by comparison with experimental data from the tests of an academic low power demonstrator Thu, 01 Jan 2015 00:00:00 GMT http://hdl.handle.net/10985/9621 2015-01-01T00:00:00Z DROUEN, Laurent CHARPENTIER, Jean-Frederic HAUVILLE, Frederic ASTOLFI, Jacques Andre SEMAIL, Eric CLENET, Stephane Le travail présenté concerne le développement d’une méthodologie de conception de systèmes hydroliens innovants de type RIM‑DRIVEN pour la récupération de l’énergie des courants de marée. L’originalité d’un système RIM‑DRIVEN réside dans la structure même de l’hydrolienne, inspirée directement des nouveaux systèmes de propulsion navale, où le rotor et le stator sont placés en périphérie de l’hélice et protégés par une tuyère, l’entrefer étant immergé. Au sein d’une structure de type RIM‑DRIVEN les phénomènes électromécaniques, thermiques et hydrodynamique sont intimement couplés. Du fait du très fort couplage des phénomènes physiques au sein du système, cette méthodologie associe au sein d’un même environnement d’optimisation des modèles électromagnétiques et thermiques spécifiques de la génératrice avec des modèles hydrodynamique des performances de l’hélice et de l’écoulement dans l’entrefer. L’approche proposée est illustrée par une étude de cas qui concerne une machine de 10m de diamètre destinée à être implantée dans le Raz de Sein. Les modèles ont été validés par des résultats issus d’une campagne expérimentale sur un démonstrateur dédié. This paper deals with the study of an unconventional design of marine tidal turbine where the electrical generator is located in the periphery of the blades and where the magnetic gap is underwater. This kind of solution called “RIM DRIVEN” structure allows increasing the compactness and the robustness of the system. Due to the strong interaction of the multi physical phenomena, an electromagnetic model and a thermal model of the PM generator are associated with a hydrodynamic model of the blades and of the water flow in the underwater air gap. These models are used in a global coupled design approach in order to optimize, under constraints, the global efficiency of the system. This approach is illustrated in a case study which deals with the design of a 10m diameter tidal turbine. Proposed coupled models are validated by comparison with experimental data from the tests of an academic low power demonstrator http://hdl.handle.net/10985/10177 A Simulation Model for the Evaluation of the Electrical Power Potential Harnessed by a Marine Current Turbine BEN ELGHALI, Seif Eddine; BALME, Rémi; LE SAUX, Karine; BENBOUZID, Mohamed; CHARPENTIER, Jean-Frederic; HAUVILLE, Frederic This paper deals with the development of a Matlab–Simulink model of a marine current turbine system through the modeling of the resource and the rotor. The simulation model has two purposes: performances and dynamic loads evaluation in different operating conditions and control system development for turbine operation based on pitch and speed control. In this case, it is necessary to find a compromise between the simulation model accuracy and the control-loop computational speed. The blade element momentum (BEM) approach is then used for the turbine modeling. As the developed simulation model is intended to be used as a sizing and site evaluation tool for current turbine installations, it has been applied to evaluate the extractable power from the Raz de Sein (Brittany, France). Indeed, tidal current data from the Raz de Sein are used to run the simulation model over various flow regimes and yield the power capture with time. Mon, 01 Jan 2007 00:00:00 GMT http://hdl.handle.net/10985/10177 2007-01-01T00:00:00Z BEN ELGHALI, Seif Eddine BALME, Rémi LE SAUX, Karine BENBOUZID, Mohamed CHARPENTIER, Jean-Frederic HAUVILLE, Frederic This paper deals with the development of a Matlab–Simulink model of a marine current turbine system through the modeling of the resource and the rotor. The simulation model has two purposes: performances and dynamic loads evaluation in different operating conditions and control system development for turbine operation based on pitch and speed control. In this case, it is necessary to find a compromise between the simulation model accuracy and the control-loop computational speed. The blade element momentum (BEM) approach is then used for the turbine modeling. As the developed simulation model is intended to be used as a sizing and site evaluation tool for current turbine installations, it has been applied to evaluate the extractable power from the Raz de Sein (Brittany, France). Indeed, tidal current data from the Raz de Sein are used to run the simulation model over various flow regimes and yield the power capture with time. http://hdl.handle.net/10985/9258 A coupled electromagnetic / hydrodynamic model for the design of an integrated rim - driven naval propulsion system DROUEN, Laurent; CHARPENTIER, Jean-Frederic; SEMAIL, Eric; HAUVILLE, Frederic; CLENET, Stephane This paper presents an analytical multi-physic modeling tool for the design optimization of a new kind of naval propulsion system. This innovative technology consists in an electrical permanent magnet motor that is integrated into a duct and surrounds a propeller. Compared with more conventional systems such as pods, the electrical machine and the propeller have the same diameter. Thus, their geometries, in addition to speed and torque, are closely related and a multidisciplinary design approach is relevant. Two disciplines are considered in this analytical model: electromagnetism and hydrodynamics. An example of systematic design for a typical application (a rim-driven thruster for a patrol boat) is then presented for a set of different design objectives (efficiency, mass, etc). The effects of each model are commented Tue, 01 Jan 2008 00:00:00 GMT http://hdl.handle.net/10985/9258 2008-01-01T00:00:00Z DROUEN, Laurent CHARPENTIER, Jean-Frederic SEMAIL, Eric HAUVILLE, Frederic CLENET, Stephane This paper presents an analytical multi-physic modeling tool for the design optimization of a new kind of naval propulsion system. This innovative technology consists in an electrical permanent magnet motor that is integrated into a duct and surrounds a propeller. Compared with more conventional systems such as pods, the electrical machine and the propeller have the same diameter. Thus, their geometries, in addition to speed and torque, are closely related and a multidisciplinary design approach is relevant. Two disciplines are considered in this analytical model: electromagnetism and hydrodynamics. An example of systematic design for a typical application (a rim-driven thruster for a patrol boat) is then presented for a set of different design objectives (efficiency, mass, etc). The effects of each model are commented http://hdl.handle.net/10985/8688 Numerical study of a Flexible Sail Plan submitted to pitching : Hysteresis phenomenon and effect of rig Adjustments AUGIER, Benoit; HAUVILLE, Frederic; BOT, Patrick; AUBIN, Nicolas; DURAND, Mathieu A numerical investigation of the dynamic Fluid Structure Interaction (FSI) of a yacht sail plan submitted to harmonic pitching is presented to analyse the system's dynamic behaviour and the effects of motion simplifications and rigging adjustments on aerodynamic forces. It is shown that the dynamic behaviour of a sail plan subject to yacht motion clearly deviates from the quasi-steady theory. The aerodynamic forces presented as a function of the instantaneous apparent wind angle show hysteresis loops. It is shown that the hysteresis phenomenon dissipates some energy and that the dissipated energy increases strongly with the pitching reduced frequency and amplitude. The effect of reducing the real pitching motion to a simpler surge motion is investigated. Results show significant discrepancies with underestimated aerodynamic forces and no more hysteresis when a surge motion is considered. However, the superposition assumption consisting in a decomposition of the surge into two translations normal and collinear to the apparent wind is verified. Then, simulations with different dock tunes and backstay loads highlight the importance of rig adjustments on the aerodynamic forces and the dynamic behaviour of a sail plan. The energy dissipated by the hysteresis is higher for looser shrouds and a tighter backstay.  Yacht sails dynamic fluid structure interaction is simulated in harmonic pitching  Aerodynamic forces show hysteresis associated to energy dissipation  Dissipated energy increases with pitching frequency and amplitude  Hysteresis is cancelled and forces underestimated when motion is reduced to surge  Looser shrouds and tighter backstay increase dissipated energy Wed, 01 Jan 2014 00:00:00 GMT http://hdl.handle.net/10985/8688 2014-01-01T00:00:00Z AUGIER, Benoit HAUVILLE, Frederic BOT, Patrick AUBIN, Nicolas DURAND, Mathieu A numerical investigation of the dynamic Fluid Structure Interaction (FSI) of a yacht sail plan submitted to harmonic pitching is presented to analyse the system's dynamic behaviour and the effects of motion simplifications and rigging adjustments on aerodynamic forces. It is shown that the dynamic behaviour of a sail plan subject to yacht motion clearly deviates from the quasi-steady theory. The aerodynamic forces presented as a function of the instantaneous apparent wind angle show hysteresis loops. It is shown that the hysteresis phenomenon dissipates some energy and that the dissipated energy increases strongly with the pitching reduced frequency and amplitude. The effect of reducing the real pitching motion to a simpler surge motion is investigated. Results show significant discrepancies with underestimated aerodynamic forces and no more hysteresis when a surge motion is considered. However, the superposition assumption consisting in a decomposition of the surge into two translations normal and collinear to the apparent wind is verified. Then, simulations with different dock tunes and backstay loads highlight the importance of rig adjustments on the aerodynamic forces and the dynamic behaviour of a sail plan. The energy dissipated by the hysteresis is higher for looser shrouds and a tighter backstay. http://hdl.handle.net/10985/14895 Experimental validation of unsteady models for wind / sails / rigging fluid structure interaction AUGIER, Benoit; BOT, Patrick; HAUVILLE, Frederic; DURAND, Mathieu The aim of this paper is to present the work of experimental validation elements of the aero elastic and unsteady model ARAVANTI. Numerical and Experimental results comparison is made on the rigging and sails of a J80 sail boat. Yacht modelling demands to consider unsteady phenomena resulting from the sea state, variations of wind speed and direction, yacht motion or trimming by the crew. A dedicated instrumentation is developed to measure the loads in shrouds and tension points of the sail, the apparent wind, the yacht motion, the sails flying shape and the navigation data. A special effort is made on sensors calibration, physical measurement comprehension and data synchronisation. Comparison with numerical results shows that the loads and flying shapes are well predicted by the model. Fri, 01 Jan 2010 00:00:00 GMT http://hdl.handle.net/10985/14895 2010-01-01T00:00:00Z AUGIER, Benoit BOT, Patrick HAUVILLE, Frederic DURAND, Mathieu The aim of this paper is to present the work of experimental validation elements of the aero elastic and unsteady model ARAVANTI. Numerical and Experimental results comparison is made on the rigging and sails of a J80 sail boat. Yacht modelling demands to consider unsteady phenomena resulting from the sea state, variations of wind speed and direction, yacht motion or trimming by the crew. A dedicated instrumentation is developed to measure the loads in shrouds and tension points of the sail, the apparent wind, the yacht motion, the sails flying shape and the navigation data. A special effort is made on sensors calibration, physical measurement comprehension and data synchronisation. Comparison with numerical results shows that the loads and flying shapes are well predicted by the model. http://hdl.handle.net/10985/11017 Inviscid approach for upwind sails aerodynamics. How far can we go? AUBIN, Nicolas; AUGIER, Benoit; BOT, Patrick; HAUVILLE, Frederic; FLOCH, Ronan This work presents a full-scale experimental study of a yacht rig and sails in real upwind sailing conditions and a comparison with Fluid Structure Interaction (FSI) simulations with the ARAVANTI model (Finite Element Method for the structure and Vortex Lattice Method for the fluid). An specific on-board instrumentation system simultaneously measures loads in the rig and sails, sailing data (wind, boat attitude and speed) and the shape of sails in real navigation conditions (flying shape). Flying shape parameters are extracted using the camera-based VSPARS system to characterize the effects of sail trims and to be compared with the results of the simulation. The potential flow solver gives fast and accurate predictions of both the flying shape and the loads in the rig in most conditions. The inviscid approach, commonly used in the early stage of design, must be checked, as in particular cases where the sails are heavily loaded, flow separation is significant and results from a potential flow solver are inaccurate. A new version of the model including the heel angle as an additional degree of freedom in the structural solver enables to detect when the inviscid flow approach overestimates the aerodynamic load. This upgrade improves the utility and reliability of the inviscid flow approach which remains relevant at the early stages of design as it is much more cost-effective than RANS models. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/11017 2016-01-01T00:00:00Z AUBIN, Nicolas AUGIER, Benoit BOT, Patrick HAUVILLE, Frederic FLOCH, Ronan This work presents a full-scale experimental study of a yacht rig and sails in real upwind sailing conditions and a comparison with Fluid Structure Interaction (FSI) simulations with the ARAVANTI model (Finite Element Method for the structure and Vortex Lattice Method for the fluid). An specific on-board instrumentation system simultaneously measures loads in the rig and sails, sailing data (wind, boat attitude and speed) and the shape of sails in real navigation conditions (flying shape). Flying shape parameters are extracted using the camera-based VSPARS system to characterize the effects of sail trims and to be compared with the results of the simulation. The potential flow solver gives fast and accurate predictions of both the flying shape and the loads in the rig in most conditions. The inviscid approach, commonly used in the early stage of design, must be checked, as in particular cases where the sails are heavily loaded, flow separation is significant and results from a potential flow solver are inaccurate. A new version of the model including the heel angle as an additional degree of freedom in the structural solver enables to detect when the inviscid flow approach overestimates the aerodynamic load. This upgrade improves the utility and reliability of the inviscid flow approach which remains relevant at the early stages of design as it is much more cost-effective than RANS models. http://hdl.handle.net/10985/15097 Experimental and numerical trimming optimizations for a mainsail in upwind conditions SACHER, Matthieu; HAUVILLE, Frederic; DUVIGNEAU, Régis; LE MAITRE, Olivier; AUBIN, Nicolas; DURAND, Mathieu This paper investigates the use of meta-models for optimizing sails trimming. A Gaussian process is used to robustly approximate the dependence of the performance with the trimming parameters to be optimized. The Gaussian process construction uses a limited number of performance observations at carefully selected trimming points, potentially enabling the optimization of complex sail systems with multiple trimming parameters. We test the optimization procedure on the (two parameters) trimming of a scaled IMOCA mainsail in upwind conditions. To assess the robustness of the Gaussian process approach, in particular its sensitivity to error and noise in the performance estimation, we contrast the direct optimization of the physical system with the optimization of its numerical model. For the physical system, the optimization procedure was fed with wind tunnel measurements, while the numerical modeling relied on a fully non-linear Fluid-Structure Interaction solver. The results show a correct agreement of the optimized trimming parameters for the physical and numerical models, despite the inherent errors in the numerical model and the measurement uncertainties. In addition, the number of performance estimations was found to be affordable and comparable in the two cases, demonstrating the effectiveness of the approach. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/15097 2016-01-01T00:00:00Z SACHER, Matthieu HAUVILLE, Frederic DUVIGNEAU, Régis LE MAITRE, Olivier AUBIN, Nicolas DURAND, Mathieu This paper investigates the use of meta-models for optimizing sails trimming. A Gaussian process is used to robustly approximate the dependence of the performance with the trimming parameters to be optimized. The Gaussian process construction uses a limited number of performance observations at carefully selected trimming points, potentially enabling the optimization of complex sail systems with multiple trimming parameters. We test the optimization procedure on the (two parameters) trimming of a scaled IMOCA mainsail in upwind conditions. To assess the robustness of the Gaussian process approach, in particular its sensitivity to error and noise in the performance estimation, we contrast the direct optimization of the physical system with the optimization of its numerical model. For the physical system, the optimization procedure was fed with wind tunnel measurements, while the numerical modeling relied on a fully non-linear Fluid-Structure Interaction solver. The results show a correct agreement of the optimized trimming parameters for the physical and numerical models, despite the inherent errors in the numerical model and the measurement uncertainties. In addition, the number of performance estimations was found to be affordable and comparable in the two cases, demonstrating the effectiveness of the approach. http://hdl.handle.net/10985/15135 Modal Analysis of Pressures on a Full-Scale Spinnaker DEPARDAY, Julien; AUGIER, Benoit; RABAUD, Marc; MOTTA, Dario; LE PELLEY, David; BOT, Patrick; HAUVILLE, Frederic While sailing offwind, the trimmer typically adjusts the downwind sail "on the verge of luffing", letting occasionally the luff of the sail flapping. Due to the unsteadiness of the spinnaker itself, maintaining the luff on the verge of luffing needs continual adjustments. The propulsive force generated by the offwind sail depends on this trimming and is highly fluctuating. During a flapping sequence, the aerodynamic load can fluctuate by 50% of the average load. On a J/80 class yacht, we simultaneously measured timeresolved pressures on the spinnaker, aerodynamic loads, boat and wind data. Significant spatio-temporal patterns are detected in the pressure distribution. In this paper we present averages and main fluctuations of pressure distributions and of load coefficients for different apparent wind angles as well as a refined analysis of pressure fluctuations, using the Proper Orthogonal Decomposition (POD) method. POD shows that pressure fluctuations due to luffing of the spinnaker can be well represented by only one proper mode related to a unique spatial pressure pattern and a dynamic behavior evolving with the Apparent Wind Angles. The time evolution of this proper mode is highly correlated with load fluctuations. Moreover, POD can be employed to filter the measured pressures more efficiently than basic filters. The reconstruction using the first few modes allows to restrict to the most energetic part of the signal and remove insignificant variations and noises. This might be helpful for comparison with other measurements and numerical simulations. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/15135 2016-01-01T00:00:00Z DEPARDAY, Julien AUGIER, Benoit RABAUD, Marc MOTTA, Dario LE PELLEY, David BOT, Patrick HAUVILLE, Frederic While sailing offwind, the trimmer typically adjusts the downwind sail "on the verge of luffing", letting occasionally the luff of the sail flapping. Due to the unsteadiness of the spinnaker itself, maintaining the luff on the verge of luffing needs continual adjustments. The propulsive force generated by the offwind sail depends on this trimming and is highly fluctuating. During a flapping sequence, the aerodynamic load can fluctuate by 50% of the average load. On a J/80 class yacht, we simultaneously measured timeresolved pressures on the spinnaker, aerodynamic loads, boat and wind data. Significant spatio-temporal patterns are detected in the pressure distribution. In this paper we present averages and main fluctuations of pressure distributions and of load coefficients for different apparent wind angles as well as a refined analysis of pressure fluctuations, using the Proper Orthogonal Decomposition (POD) method. POD shows that pressure fluctuations due to luffing of the spinnaker can be well represented by only one proper mode related to a unique spatial pressure pattern and a dynamic behavior evolving with the Apparent Wind Angles. The time evolution of this proper mode is highly correlated with load fluctuations. Moreover, POD can be employed to filter the measured pressures more efficiently than basic filters. The reconstruction using the first few modes allows to restrict to the most energetic part of the signal and remove insignificant variations and noises. This might be helpful for comparison with other measurements and numerical simulations. http://hdl.handle.net/10985/15098 Wind tunnel investigation of dynamic trimming on upwind sail aerodynamics AUBIN, Nicolas; AUGIER, Benoit; SACHER, Matthieu; FLAY, Richard G.J.; BOT, Patrick; HAUVILLE, Frederic An experiment was performed in the Yacht Research Unit’s Twisted Flow Wind Tunnel (University of Auckland) to test the effect of dynamic trimming on three IMOCA 60 inspired mainsail models in an upwind (AWA = 60 ) unheeled configuration. This study presents dynamic fluid structure interaction results in well controlled conditions (wind, sheet length) with a dynamic trimming system. Trimming oscillations are done around an optimum value of CFobj previously found with a steady trim. Different oscillation amplitudes and frequencies of trimming are investigated. Measurements are done with a 6 component force balance and a load sensor giving access to the unsteady mainsail sheet load. The driving CFx and optimization target CFobj coefficient first decrease at low reduced frequency fr for quasisteady state then increase, becoming higher than the steady state situation. The driving force CFx and the optimization target coefficient CFobj show an optimum for the three different design sail shapes located at fr = 0:255. This optimum is linked to the power transmitted to the rig and sail system by the trimming device. The effect of the camber of the design shape is also investigated. The flat mainsail design benefits more than the other mainsail designs from the dynamic trimming compared to their respective steady situtation. This study presents dynamic results that cannot be accurately predicted with a steady approach. These results are therefore valuable for future FSI numerical tools validations in unsteady conditions. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10985/15098 2016-01-01T00:00:00Z AUBIN, Nicolas AUGIER, Benoit SACHER, Matthieu FLAY, Richard G.J. BOT, Patrick HAUVILLE, Frederic An experiment was performed in the Yacht Research Unit’s Twisted Flow Wind Tunnel (University of Auckland) to test the effect of dynamic trimming on three IMOCA 60 inspired mainsail models in an upwind (AWA = 60 ) unheeled configuration. This study presents dynamic fluid structure interaction results in well controlled conditions (wind, sheet length) with a dynamic trimming system. Trimming oscillations are done around an optimum value of CFobj previously found with a steady trim. Different oscillation amplitudes and frequencies of trimming are investigated. Measurements are done with a 6 component force balance and a load sensor giving access to the unsteady mainsail sheet load. The driving CFx and optimization target CFobj coefficient first decrease at low reduced frequency fr for quasisteady state then increase, becoming higher than the steady state situation. The driving force CFx and the optimization target coefficient CFobj show an optimum for the three different design sail shapes located at fr = 0:255. This optimum is linked to the power transmitted to the rig and sail system by the trimming device. The effect of the camber of the design shape is also investigated. The flat mainsail design benefits more than the other mainsail designs from the dynamic trimming compared to their respective steady situtation. This study presents dynamic results that cannot be accurately predicted with a steady approach. These results are therefore valuable for future FSI numerical tools validations in unsteady conditions.