Effect of Shape Parameterization on Aerodynamic Evolutionary Optimization of Viscous Transonic Airfoils

The effect of airfoil shape parameterization on optimum design and its influence on the convergence of the evolutionary optimization process is presented. Three different airfoil parametric methods including PARSEC, Sobieczky and B-Spline (Bezier curve) are studied and a new method for airfoil shape parameterization is also presented. The new method takes into consideration the characteristics of viscous transonic flows particularly around the trailing edge. The methods are applied to airfoil shape optimization at high Reynolds number turbulent flow conditions using a Genetic Algorithm. An unstructured grid Navier-Stokes flow solver with a two-equation K-ε turbulence model is used to evaluate the objective function. The aerodynamic characteristics of the optimum airfoil obtained from the proposed parametric method are compared with those from alternative methods. It is concluded that the new method is capable of finding efficient and optimum airfoils in fewer number of evaluations.