Airfoil aerodynamics optimization under uncertain operating conditions

Abstract

An aerodynamic robust optimization of a 2D airfoil is presented. Robust optimization aims to find a design which is less sensitive to small changes in uncertain quantities. Aerodynamic performance of airfoil is studied under variation of Mach number and angle of attach as operational uncertainties. The optimal aerodynamic shape of airfoil is computed by maximizing lift and drag coefficient ratio. Airfoil aerodynamic perfomance is evaluated using XFOIL solver. NACA 0012 is adopted as a basic airfoil design and optimized for robustness using Taguchi method. Signal-to-Noise ratio (S/N) of Taguchi method for larger the better is applied as robustness index. Nine of eleven variables of PARSEC airfoil parameters with 3 levels for each factors are selected as design variables and distributed using L27 fractional orthogonal array as the design of experiment. The optimization process does not only increase the average performance of lift-to-drag ratio but also decrease the standard deviation. The optimization strategy significantly improves the aerodynamic performance of the basic NACA 0012 from 21.76 to 36.79 or improves 69% of the robustness index.