Hypersonic Vehicle Analyses: The Needs and Challenges of Multidisciplinary Simulations

The development of hypersonic vehicles is of broad international interest today for applications in national security, deep space exploration, and the emerging space economy. While the first hypersonic vehicle flew more than 70 years ago, their effective design still faces major technical challenges. The overarching cause of this difficulty stems from the fact that many key individual physical processes relevant to hypersonic flight are tightly coupled. The gas dynamics of the air flow around the vehicle creates temperatures of thousands of degrees leading to internal energy excitation and chemical reactions. The hot, oxidized gas in contact with the surfaces of the vehicle leads to material response phenomena such as conduction, radiation, and ablation. The thermally soaked material alters the structural response to the aerodynamic loading. Changes in the vehicle outer mold line due to ablation and structural deformation change the basic aerodynamic performance and thus affect the flight dynamics. With advanced numerical algorithms and modern computer architectures, it is becoming possible to include many of these complex processes in hypersonic vehicle analyses. This talk will review the current status for computational modeling of each separate discipline as well as efforts to couple these processes together. Key aspects for coupling include consideration of timescales associated with different processes and multi-fidelity simulation approaches.