Optimization of Three-Dimensional Wings in Ground Effect Using Multiobjective Genetic Algorithm

Abstract

Shape optimization with a multiobjective optimization technique and tradeoff analysis of the three-dimensional wings-in-ground effect have been performed. Unlike an airplane out-of-ground effect, a wing-in-ground vehicle has to satisfy static height stability in order to cruise steadily in ground effect. However, it is difficult to simultaneously satisfy both high aerodynamic performance and static height stability because of the strong tradeoffs between the two. A multiobjective optimization technique can address this problem. In multiobjective optimization, the optimum is not unique; rather, it is a set of nondominated potential solutions called Pareto optima. In this study, after 19 evolutions of a genetic algorithm, 74 nondominated Pareto optima are obtained and four different groups can be observed from the Pareto optima. Each group represents a set of the potential global solutions for a single objective or combined objectives. The analysis of the Pareto optima suggests that the lift is increased because of increased pressure on the lower wing surface, but the influence of pressure on the upper surface is not significant. The wing thickness and curvature increase the lift further, but they are not favorable for static height stability and the lift drag ratio; a swept-forward wing can improve the static height stability.