Optimization of Supercritical Airfoil Design with Buffet Effect

Abstract

In transonic flight within a certain range of Mach number and angle of attack, the flowfield becomes unstable, and it produces an oscillating aerodynamic force: a phenomenon commonly known as transonic buffet. This load can inflict severe damage on the structure of an aircraft wing, and so it is necessary to consider the buffet effect in supercritical airfoil design. In the present work, the first objective is to find optimal profiles for minimizing the time-averaged drag and buffet magnitude. The second objective is to compare new airfoils and derive insights for transonic supercritical airfoil design to reduce buffet effect. The OAT15A airfoil is chosen as the baseline design, and then a numerical scheme is developed to obtain time-averaged aerodynamic coefficients and buffet parameters. A geometry disturbance method with smoothness check is introduced to develop a set of new airfoils. Simulations of the new airfoils are conducted to populate the sample space for surrogate modeling. A neural network method is used to build the surrogate models, which are then employed in a genetic algorithm to select optimized airfoils. Finally, the behavior and physics of the optimal airfoils are simulated and analyzed.