Aerodynamic of modern square head sails: a comparative study between wind-tunnel experiments and RANS simulations

Abstract

A commercial Reynolds Average Navier Stokes code (ANSYS CFX10) is used here to compare with wind-tunnel experiments of a modern ORMA60’ rig in upwind condition. Two mainsails of different tip chord length and a head sail are tested. The flying shapes are acquired by a digital camera to feed the numerical model with the same geometry has used in the experiments. The results of the study underline the need for an extreme accuracy in the acquisition of the flying shapes. It is also noted that modelling the hull in addition to the mast and sails improve the prediction significantly. Presence of a hull tends to tangle the tip vortices generated by the sails’ foot and affect the flow up to the middle of the mast, whereby increasing both lift and drag. Scaling effects are finally discussed