Transonic Airfoil Study Using Sonic Plateau, Optimization and Off-Design Performance Maps

A number of transonic airfoils, designed using differing approaches, are evaluated over a\udwide range of operating conditions, using a tool for generating aerodynamic performance\udmaps. Details of key performance boundaries are also extracted, including drag divergence\udand separation onset. The aerodynamic performance maps and boundaries, which are based\udupon extensive use of a rapid 2D CFD tool, are first demonstrated on an existing airfoil, for\udwhich the design condition is known and for which experimental data is available.\udAerodynamic maps are then presented for a series of airfoils which are designed using a\udsonic plateau, inverse design approach. Further maps are presented for airfoils designed\udusing single-point and multi-point optimization. The impact of the alternative design\udapproaches is studied, using the performance maps and the resulting characteristics of the\udperformance boundaries. In particular, the trade-off between drag divergence and the onset\udof separation, combined with viscous and wave drag development, is presented. The study\udprovides some insights into the challenge of achieving a well posed optimization formulation\udfor transonic airfoil design