Abstract
Micro-genetic algorithm has been applied incorporating boundary element analysis to the optimal design of lifting bodies, i.e., hydrofoil, propeller etc. In case of hydrofoil, the 2-dimensional section with NACA 66 (mod.) thickness distribution and NACA a=0.8 camber distribution are fitted with B-spline polygon vertices. Then the change in shape of the 2-D section is made by shifting B-spline polygon vertices vertically. Using this generated section, trapezoidal hydrofoil is analyzed by 3-D boundary element method. GA then updates the section shape by shifting polygon vertices and finally finds the optimum section, for which, hydrofoil attains highest L/D ratio satisfying some imposed constraints. In case of propeller, chord, pitch, maximum thickness and camber ratios are also fitted with B-spline. The variations in the distributions are made by shifting B-spline polygon vertices, and improved propeller of highest efficiency is found by GA satisfying some design constraints. In this study, μGA is found useful and prospective tool for the optimization of lifting bodies incorporating analysis method because of its faster convergence.
