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C-Class Catamaran Wing Performance Optimisation Nils Haack and Robert Prosser Computational Fluid Dynamics Expert Group Introduction The main factor in wining sailing races is the up-wind performance of the boats. In the C-Class this lead to the development of wings instead of the conventional soft sail. For the up-wind performance it is imperative to set up the wing for a high lift/drag ratio to generate as much Driving force as possible (see Figure 1). True wind Apparent wind Boat speed Drive Drag Lift Lateral Figure 1: Forces aerodynamic forces acting on the boat Figure 2: Wing reaction on boat at apparent wind direction of 35 degrees Project Aim The optimum wing configuration is determined by 2D simulations of the profile in different configurations. For this purpose the AoA (angle of attack) is defined as the angle between the upstream flow direction and the line between mast and trailing edge of the flap. With an apparent wind at 35° to the sailing direction of the boat, the setup of the wing has different effects on the boat (see Figure 2). The different wing-profile properties are shown in Figure 3-5. Figure 3: Lift Coefficient Figure 4: Drag Coefficient Figure 5: Lift/Drag Further studies Investigation of the effect of the water surface and the flying hull on the flow at the root of the wing. The investigation of the airflow around the root of the wing will be done using 3D simulations. The cases are run in steady state with the standard K − ε model [1]. References [1]B E Launder and B I Sharma. Application of the energy-dissipation model of turbulence to the calculation of flow near a spinning disc. Letters in heat and mass transfer, 1:131–138, 1974. School of Mechanical, Aerospace & Civil Engineering Postgraduate Research Conference, PGR-MACE10