Research Information System
The Society of Naval Architects and Marine Engineers, vol.8, no.1, pp.39-64, 2023 (Peer-Reviewed Journal)
Curved tip effect on the performance of three-dimensional (3-D) cavitating hydrofoils
moving steadily under a free water surface has been investigated numerically by an iterative
boundary element method (IBEM) developed before. The IBEM has been modified and extended to
solve this problem. The fluid is assumed to be inviscid, incompressible and the flow irrotational. All
variables and equations are made non-dimensional to achieve a very quick and consistent numerical
scheme. The IBEM is based on the Green’s theorem. The hydrofoil problem and the free surface
problem are solved separately with the effects of each other via their potential values in an iterative
manner. Both the 3-D hydrofoil surface and the free surface are modelled with constant strength
source and constant strength doublet panels. The kinematic boundary condition is applied on the
hydrofoil surface while the linearized kinematic and dynamic combined condition is applied on the
free water surface. The method was validated extensively before for cavitating hydrofoils but not
when combined with tip curvature. It is first applied to a tapered wing and the results are compared
with those of experiments. Later, it is applied to a tapered hydrofoil with curved tip upwards or
downwards. The effects of curved tip shape on cavitating hydrofoil performance have been
investigated. It is found that the curved tip caused an increase in loading and cavitation volume in
unbounded flow domain. It is also obtained that curved tip caused a decrease in loading on the
hydrofoil for lower chord-based Froude numbers than 0.8.