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Transcript
```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 .
References
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