LOW-DRAG BASE VENTED HYDROFOILS DESIGNED FOR OPERATION NEAR THE FREE SURFACE

Linearized cavity flow theory is used to determine the shape and cavity drag of a series of low cavity drag base vented hydrofoils having constant chordwise pressure distribution and operating at a particular depth-chord ratio. This family of base vented hydrofoils is generated by perturbing a quasiparabolic nonlifting thickness distribution so as to produce a base-vented lifting hydrofoil with a uniform loading. Numerical calculations are carried out to determine the shape, cavity drag coefficient, section modulus, and lift-drag ratio for two-dimensional basevented hydrofoils over a wide range of lift coefficients and incipient cavitation numbers at various depth chord ratios. Families of zero cavity drag base-vented foils are also presented for the same depth-chord ratios. (Author)