Abstract

THIART, G.D.. Numerical lifting line theory for a hydrofoil near a free surface. R&D j. (Matieland, Online) [online]. 1994, vol.10, pp.18-23. ISSN 2309-8988.

A numerical lifting line theory for the calculation of lift on a hydrofoil of finite span near a free surface is presented. Nonlinearities in the lift curve slope of the hydrofoil sections are accounted for, and a downwash correction due to the presence of the free surface is also included. Theoretical results are compared with experimental results for a 5.11 aspect ratio hydrofoil of the circular arc type. The lift curves of the hydrofoil sections as function of depth of submergence and angle of attack were calculated by means of a linearized free surface boundary condition panel method. These section lift curves were used to calculate the finite span hydrofoil lift curves by means of the numerical lifting line theory. The theoretical results compare favourably with the experimental results, and it is shown that much better agreement between theory and experiment is obtained as compared to results obtained with a simple aspect ratio correction factor based on Prandtl's lifting line theory.

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