Optimization of Wings in Ground Effect Using Multi-Objective Genetic Algorithm

Abstract

The shape optimization using the multi-objective genetic algorithm and the analysis of the 3-dimensional wings in ground effect has been performed. Unlike an airplane flying out of ground effect, wings in ground effect have to satisfy static height stability to cruise steadily above the ground or water surface. In this study, both aerodynamic performance and static height stability are considered as objectives. Due to the multi-objective optimization, the optimal solutions are not unique but a set of non-dominated potential solutions: Pareto optima. After twenty evolutions, 74 non-dominated Pareto optima can be obtained. Three objectives, lift coefficient, lift-to-drag ratio and static height stability, are strongly tradeoff each other so that the unique and dominate solution is not existed. The Pareto optima obtained in this study are placed on the edge of the objective space. From the analysis of the Pareto optima, static height stability was improved at the lower height and the higher angle of attack. The lift-to-drag ratio increases with the lower height since the pressure on the lower wing surface increases while that on the upper surface remains constant. The influence of the tip vortex reduces as ground approached.