Lifting-Line Theory of a Supercavitating Hydrofoil in Two-Dimensional Shear Flow (Application to Partial Cavitation)(Turbomachinery)

The existing lifting-line theory for a supercavitating hydrofoil in two-dimensional shear flow (where velocity varies in both spanwise and vertical directions) between two parallel planes is applied to partial cavitation under the same flow conditions. A lifting-line equation is derived from combining the assumption holding the lift coefficient two-dimensionally at any spanwise position with an up-wash velocity induced along a lifting-line. The hydrofoil for numerical examples is flat in section, rectangular in plan form, and has a 5 degree attack angle. Effects of two kinds of shear parameters, cavitation number, and taper ratio on local lift coefficient, total lift coefficient and induced drag coefficient are clarified through numerical calculations. Cavity length distributions are obtained on the basis of the assumption that the relationship between cavitation number and attack angle is two-dimensional at any spanwise position.