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| Deparday, Julien; Bot, Patrick; Hauville, Frédéric; Augier, Benoit; Rabaud, Marc; Motta, Dario; Le Pelley, David. |
| While sailing offwind, the trimmer typically adjusts the downwind sail “on the verge of luffing”, occasionally letting the luff of the sail flap. Due to the unsteadiness of the spinnaker itself, maintaining the luff on the verge of luffing requires 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 time-resolved pressures on the spinnaker, aerodynamic loads, boat data and wind data. Significant spatio-temporal patterns were detected in the pressure distribution. In this paper we present averages and main fluctuations of pressure distributions... |
| Tipo: Text |
Palavras-chave: Full scale experiment; Instrumented boat; Spinnaker; Fluid structure interaction; POD; Unsteady. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00597/70918/69156.pdf |
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| Deparday, Julien; Augier, Benoit; Bot, Patrick. |
| In the present study we investigate the flapping instability of a light, soft, highly cambered membrane subject to wind loading. An original in-situ experiment is developed where time-resolved pressures and forces are measured on a full-scale yacht downwind sail called a spinnaker. Particular features of this aero-elastic problem are that the membrane is weakly constrained – held only at three corners –, has a free leading edge, and has no proper shape in the absence of wind loading. In usual operating conditions, the soft structure is subject to a flapping instability giving rise to almost periodic folding and unfolding of the fore part of the sail, associated to strong variations of pressures and forces. This dynamic behavior is analyzed in detail and... |
| Tipo: Text |
Palavras-chave: Fluid structure interaction; Full-scale experiment; Modal decomposition; Pressure measurements; Soft membrane. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00444/55561/60479.pdf |
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