Computational Sensitivity Analysis for the Aerodynamic Design of Supersonic and Hypersonic Air Vehicles

Abstract : The conceptual design of hypersonic air vehicles relies on computational methods to produce estimates of aerodynamic, structural, thermal protection, and propulsion design requirements. Solving the design optimization problem presented by these competing requirements using traditional low-fidelity vehicle models and flow simulations is inadequate because these models represent the underlying physics of the combined disciplines poorly. In order to assess the potential of using physically-accurate flow simulation tools and high-resolution geometry modeling tools in the conceptual design stage, the sensitivity of a hypersonic air vehicle's lift-to-drag ratio to geometric variations was calculated using a computational framework developed for this project. The framework is unique in its integration of modern design tools such as parametric vehicle geometry models, Eulerian flow simulations with automated volumetric mesh generation and refinement, Kriging response surface generation, and global sensitivity analysis. The sensitivity of a hypersonic vehicle's lift-to-drag ratio to changes in two planform parameters was completed and demonstrated the capabilities of the framework to perform global sensitivity analyses. When the design space was extended to nine geometric parameters, the initial application of the framework failed and the results of the global sensitivity analysis were inconclusive. The global sensitivity analysis failed due to the sparse sampling of the design space, the large range of each design parameter, the large interaction effects between design variables caused by the non-linearities of hypersonic flow, and the interpolation imposed by the Kriging response surface in a case with greater design parameter interactions than were expected.