CFD calculations on the sail-like three dimensional airfoils

Abstract

It is important to understand flow characteristics and the performance of sails for both sailors and designers who want to have efficient thrust of yacht. In this paper the viscous flows around sail-like rigid wings, which are similar to main and jib sails of a 30-foot sloop, are calculated using a CFD tool. Lift, drag and thrust forces are estimated for various gap distances between the two sails and the centre of effort of the sail system is obtained. Also wind tunnel experiments were carried out to measure aerodynamic forces acting on the combined sails. It is found that the combination of two sails produces a lift force larger than the sum of that produced separately by each sail and the gap distance between the two sails is an important factor to determine total lift and thrust. The effect of heel on sail performance is also investigated. The heeled sail system has lower lift and drag than the upright sails.