FSI investigation on stability of downwind sails with an automatic dynamic trimming
TypeArticles dans des revues avec comité de lecture
Gennakers are lightweight and flexible sails, used for downwind sailing configurations. Qualities sought for this kind of sail are propulsive force and dynamic stability. To simulate accurately the flow surrounding a sail, several problems need to be solved. Firstly, the structural code has to take into account cloth behavior, orientation and reinforcements. Moreover, wrinkles need to be taken into account through modeling or fine enough discretization. Secondly, the fluid solver needs to reproduce the atmospheric boundary layer as an input boundary condition, and be able to simulate separation. Thirdly, the fluid-structure interaction (FSI) is strongly coupled due to the lightness and the flexibility of the structure. The added mass is three orders of magnitude greater than the mass of the sail, and large structural displacement occur, which makes the coupling between the two solvers difficult to achieve. Finally, the problem is unsteady, and dynamic trimming is important to the simulation of gennakers (Graf and Renzsch, 2006). As the FSI procedure is detailed in Durand (2012), the present work is rather focused on its application to downwind sail stability. The main objective of this paper is to use numerical simulations to model gennakers, in order to predict both propulsive force and sail dynamic stability. Recent developments from Durand (2012) are used to solve these problems mentioned earlier, using a finite element structural analysis program dedicated to sails and rig simulations coupled with an unsteady Reynolds averaged Navier–Stokes equations (URANSE) solver. The FSI coupling is done through a partitioned approach with quasi-monolithic properties. An arbitrary Lagrangian Eulerian (ALE) formulation is used, hence the fluid mesh follows the structural deformation while keeping the same topology. The fluid mesh deformation is carried out with a fast, robust and parallelized method based on the propagation of the deformation state of the sail boundary fluid faces (Durand et al., 2010). Tests were realized on a complete production chain: a sail designer from Incidences-Sails has designed two different shapes of an IMOCA60 gennaker with the SailPack software. An automatic procedure was developed to transfer data from Sailpack to a structure input file taking into account the orientation of sailcloth and reinforcements. The same automatic procedure is used for both gennakers, in order to compare dynamic stability and propulsion forces. A new method is then developed to quantify the practical stability of a downwind sail.
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DURAND, Mathieu; LOTHODE, Corentin; HAUVILLE, Frédéric; LEROYER, Alban; VISONNEAU, Michel; FLOCH, Ronan; GUILLAUME, L (Ecole Navale, 2013)Gennakers are lightweight and flexible sails, used for downwind sailing configurations. Qualities sought for this kind of sail are propulsive force and dynamic stability. To simulate accurately the flow around such a sail, ...
DURAND, Mathieu; HAUVILLE, Frédéric; BOT, Patrick; AUGIER, Benoit; ROUX, Y; LEROYER, Alban; VISONNEAU, Michel (Royal Institution of Naval Architects, 2010)Modelling the wind, sail and rig interactions on a sailing yacht is a complex subject, because the quality of simulation depends on the accuracy of both structural and fluid simulations which strongly interact. Moreover, ...
AUBIN, Nicolas; AUGIER, Benoit; BOT, Patrick; HAUVILLE, Frédéric; FLOCH, Ronan (Elsevier, 2016)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 ...
Numerical study of a Flexible Sail Plan submitted to pitching : Hysteresis phenomenon and effect of rig Adjustments AUGIER, Benoit; HAUVILLE, Frédéric; BOT, Patrick; AUBIN, Nicolas; DURAND, Mathieu (Elsevier, 2014)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 ...
AUGIER, Benoit; BOT, Patrick; HAUVILLE, Frédéric; DURAND, Mathieu (Editions de l'Ecole Polytechnique, 2013)The dynamic Fluid Structure Interaction (FSI) of yacht sails submitted to a harmonic pitching motion is numerically investigated to address both issues of aerodynamic unsteadiness and structural deformation. The model ...