Aerodynamic analysis and multi-objective optimization of wings in ground effect

Abstract

Optimization of the sectional shapes of wings in ground effect (WIG) has been performed in this study by using computational fluid dynamics (CFD) and multi-objective optimization technology. The primary factors of the aerodynamic characteristics of the wings in ground effect are the lift force, the static height stability, and the lift-to-drag ratio. The strong trade-off among aerodynamic characteristics makes it difficult to simultaneously satisfy the design requirements of high aerodynamic performance and high stability. In this study, three characteristics - the lift coefficient, the aerodynamic center of height, and the lift-to-drag ratio - are chosen as the objective functions. The aerodynamic center of height is selected, rather than static height stability, because it is more suitable for single airfoil optimization and can be directly extended to a WIG vehicle. Also, 18 coordinates in the sectional airfoil are adopted as design variables. In multi-objective optimization, the optimal solutions are not unique, but are a set of non-dominated and potential optima, called Pareto optima or Pareto sets. The Pareto optima (113 individuals) include various airfoil shapes such as a flat lower surface and a convex lower surface next to the trailing edge, which show high lift and high stability, respectively.