Constrained Aerodynamic Optimization of Three-Dimensional Wings Driven by Navier-Stokes Computations

Ar obust and efficient approach to the multiobjective constrained design, previously developed by the authors, is extended to optimization of three-dimensional aerodynamic wings. The objective is to minimize the total drag at fixed lift subject to various geometrical and aerodynamical constraints. The approach employs genetic algorithms (GAs) as an optimization tool in combination with a reduced-order-models (ROM) method, based on linked local databases obtained by full Navier‐Stokes computations. The work focuses on the following issues: geometrical representation of three-dimensional shapes, handling of sensitive nonlinear constraints such as pitching moment, and the influence of flight conditions on the results of optimization. The method, implemented in the computer code OPTIMAS (Optimization of Aerodynamic Shapes), was applied to the problem of multipoint transonic threedimensional wing optimization with nonlinear constraints. The results include a variety of optimization cases for two wings: a classical test case of ONERA M6 wing and a generic cranked transport-type wing. For the investigated class of problems, significant aerodynamic gains have been obtained. Nomenclature C D = total drag coefficient CL = total lift coefficient C M = total pitching-moment coefficient C p = pressure coefficient M = freestream Mach number N D = dimension of the search space Nws = number of sectional airfoils Q = objective function R/c = relative radius of the airfoil leading edge Re = freestream Reynolds number t/c = relative thickness of airfoil α = angle of attack θ = trailing-edge angle of airfoil