Lift and drag coefficients are predicted for a symmetrical hydrofoil, NACA 66-012, at non-zero angles of attack under supercavitating flow conditions. The hydrofoil is modelled using surface singularities and both the pressure distribution (obtained from potential flow solution) and the wall shear stress distribution (obtained from boundary layer solutions) are used to determine the hydrodynamic forces applied on the hydrofoil. To get the potential flow solution, the Panel method was used. For laminar boundary layer solution, Thwaite' s method was used combined with Mitchel criterion to decide on the transition point. Head's method was then used to solve the turbulent boundary layer in combination with Ludwig's formula for the skin friction coefficient. The system of ODE equations were then solved numerically and the hydrodynamic forces (lift and drag) were calculated at two different angles of attack in a range of cavitation numbers. Agreement between predicted values and experimental data appears to be
qualitatively good. The work shows that
using classic ideas of aeronautics, i.e., dividing the flow about a blunt body to a boundary layer with dominant viscous effects and an in viscid region outside the boundary layer may be used efficiently in order to check the suitability of a given airfoil (or to compare their performance) for use in hydrofoil ships.
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