Trans RINA, Vol 153, Part B2, Intl J Small Craft Tech, 2011 Jul-Dec 7.5.2 18 Footer Rig Design Figure 13: leeward design shape: = 30°, 33°
As a second step in the FSI investigation, the influences of main parameters have been quantified on the design of an 18 footer genoa in upwind sailing conditions (apparent wind VA=20 knots, =21°). A mainsail and a genoa are modelled but the fluid-structure interaction was studied only for the genoa. The mainsail was considered as a rigid sail (Figure 17). The genoa is first designed with all its geometric characteristics: seams, stripes, filaments, battens, reinforcements. Rhino 3D has been used to create this first model (Figure 18). Mechanical characteristics are applied on each part of the sail using RELAX.
Figure 14: leeward flying shape: = 30°, 33° Figure 17: 18 footer rig
Figure 15: windward flying shape: = 30°, 33°
Figure 18: genoa design with all its geometric characteristics.
Figure 16: tip vortex on the bottom of the genoa = 30°
©2011: The Royal Institution of Naval Architects
In this example, after only three iterations of the FSI loop between the structural and the aerodynamic codes the convergence is good, with less than a centimetre of difference between the two last sail shapes and less than 1% on driving and heeling forces between the two last iterations (see following table).
B-113
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