A Reformulated Lifting Line Theory for Supercavitating Hydrofoil Design

A new computational procedure based on a reformulated lifting line theory has been developed to represent the spanwise circulation distribution of super-cavitating hydrofoils. The vortex lattice method can consider fully submerged as well as surface piercing hydrofoils, incorporating an approximate model with free surface effects. The proposed method exactly allows for the nonlinear behavior of the hydrofoil sections which change, transitioning from a fully wetted or base cavitating regime to a partial cavitating or fully cavitating regime. In this respect, a reformulated numerical lifting line method has been developed with a new non-linear boundary condition consistent with the variable slope The method proves to be enough accurate to be used for the design of the angle of attack spanwise distribution of supercavitating surface piercing hydrofoils when applied to design a super-cavitating hydrofoil, which has been then tested at the cavitation tunnel, at different angles of attack and different cavitation indexes.