As an academic organization within the University of Palermo (Italy), our Zyz Sailing Team brings together students and professors with a shared passion for the design and manufacture of a racing sailboat. Our members have particular skill sets. Some are experienced with engineering design elements, such as CAD, the finite element method (FEM) and computational fluid dynamics (CFD), while others are expert craftsmen.
We began designing and building small sailing boats in 2008. Our latest challenge was the creation of Ercte, a 16-foot foiling catamaran constructed of marine plywood and carbon fiber reinforced plastic.
For our initial design, we chose elliptical planform hydrofoils and rectangular vertical blades, with four-digit NACA 0012 airfoils and T-rudders with four-digit NACA 0010 airfoils.
Next, we refined our initial design by to more suitable hydrodynamic airfoil sections to the hydrofoils and blades, but left the T-rudders unchanged. Specifically, we selected the airfoil cross-section from the asymmetric laminar series for horizontal surfaces (NACA 641A212) and the symmetric laminar series (NACA 65A010) for the verticals. We also replaced the elliptical-shaped planform with one that was straight-tapered, in order to simplify the manufacturing process. Finally, we joined the blade and the foil with a blending surface (depicted in green) to minimize the generated drag.
We used Ansys Fluent for evaluating the appendages, including the interference between the appendages at different positions of the vertical blades along the longitudinal axis. Simulation helped us to analyze the behavior of the hydrofoils at different velocities and incidences within a defined operational range, and select the configuration that minimized drag. The CFD results were then compared with theoretical predictions, based on the classical wing theory. We found that the calculated lift variation matched well with the theoretical lift curve. Additionally, simulation confirmed the efficiency gains available from the new (versus initial) configuration, in the defined range of velocities.
Our next project is to build upon the knowledge we’ve gained and apply it to other similar projects. As an example, we are planning to equip one of our mono-hulls with carbon-made hydrofoils. Our design efforts will focus on analyzing fluid-structure interactions using ANSYS Workbench.
To learn more about our team, please visit our website.
Contributors to this blog:
Francesco Niosi obtained a bachelor’s degree in mechanical engineering from the University of Palermo, and authored a thesis on the numerical investigation of catamaran foils. He participates in the team’s manufacturing activities.
Marco Saporito is pursuing a master’s degree in aerospace engineering at the University of Palermo. He worked on the aerodynamic design of the new hydrofoils and helped analyze the CFD results. He also contributes to the sailing team’s manufacturing endeavors.