Toward High-Enthalpy Simulations for Hypersonic Applications: The Double Cone Test Case

Author(s):

Vishal A Bhagwandin and Jubaraj Sahu

Abstract:

Computational modeling approaches for chemical and thermal nonequilibrium hypersonic flows were investigated. The test case was a canonical double-cone in a Mach 13, high-enthalpy 22 MJ/kg flow environment, modeled after the University of Queensland X3 wind tunnel experiments. State-of-the-art numerical simulations employed full Navier-Stokes with multi-specie finite-rate chemical kinetics, vibrational relaxation, coupling of vibration and dissociation via a two-temperature nonequilibrium approach, and modeling of viscosity, thermal conductivity and diffusion transport properties specifically geared for high-temperature gases. Flow-field solutions showed complex shock–shock and shock–boundary layer interactions. The high-temperature post-shock showed a high degree of dissociation of nitrogen and oxygen, vibrational excitation, and thermochemical nonequilibrium. Predicted surface pressures and peak heat flux matched well with experiment; however, uncertainties exist in the general prediction of heat flux and corner flow separation. Additionally, the use of a single-specie perfect gas model emphasized the need for modeling high-temperature gas effects. The perfect gas model retained more energy in the flow, which drastically changed the shock structures, and significantly overpredicted the extent of flow separation and peak heating.