A comparative study between wind-tunnel experiments and RANS simulations of modern square headed main sails

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Description/Abstract

A commercial code (ANSYS CFX10) which is based upon Reynolds Average Navier Stokes, is used here to compare with wind-tunnel experiments of a modern ORMA60’ rig in an 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, thereby increasing both lift and drag. The effects of scaling are discussed