Multi-Objective Hypersonic Entry Aeroshell Shape Optimization

A framework has been developed to identify hypersonic entry aeroshell shapes that are Pareto-optimal with respect to multiple conflicting objectives. The objectives and constraints are derived from the aeroshell geometry and aerodynamic performance. Shapes are parameterized using nonuniform rational B-splines for maximum design flexibility. Hypersonic aerodynamic objectives and constraints are based on rapid predictions obtained from Newtonian flow theory. Single- and multi-objective genetic algorithms are employed for optimization. This framework has been applied to the Mars Science Laboratory mission to quantify tradeoffs inherent to blunt-body aeroshells. Lift-to-drag ratio, volume, and size constraints were derived from the 70-degree sphere-cone aeroshell for this mission, and aeroshell shapes were optimized based on three conflicting objectives: drag area, longitudinal static stability, and volumetric efficiency. First, single-objective optimization revealed the extreme designs for this objective space. Next, two-objective optimization produced Pareto fronts of compromise designs that illustrate the tradeoffs among each pair of objectives. Finally, a three-objective optimization provided Pareto-optimal designs that offer simultaneous improvement in all three objectives relative to the baseline 70-degree sphere-cone aeroshell. [PUBLISHER ABSTRACT]