Design of Blown Flap Configurations Based on a Multi-element Airfoil

Abstract

In this study, a new configuration of an internally blown flap based on a multi-element airfoil for the high lift device of an amphibious aircraft is proposed and discussed. To explore the potential of current configuration, a differential evolution algorithm is employed. The optimization results show that current internally blown flap can gain the same lift enhancement with less energy consumption. The stall performance is also enhanced compared with traditional simple hinge blown flaps. The result of a parametric analysis of design parameters proves the robustness of the configuration which contributes to the employment of dual objective optimization. After the optimization design, the response to jet momentum coefficients is analyzed and the result shows that there exist two critical momentum coefficients that separate the lift vs. jet momentum curve into three segments and each segment corresponds to different flow separation phenomena. The circulation control rule for a multi-element airfoil with inserted energy if different and more complicated.