Hypersonic Flow Simulation towards Space Propulsion Geometries

This work aims to expand the applicability of an open-source numerical tool to solve hypersonic gas dynamic flows for space propulsion geometries. This is done by validating the code using two well-known hypersonic test cases, the double cone and the hollow cylinder flare, used by the NATO Research and Technology Organization for the validation of hypersonic flight for laminar viscous-inviscid interactions (D. Knight, “RTO WG 10 - Test cases for CFD validation of hypersonic flight,” in 40th AIAA Aerospace Sciences Meeting & Exhibit, 2002). The Computational Fluid Dynamic (CFD) simulation is conducted using the two-temperature solver hy2Foam that is capable to study external aerodynamics in re-entry flows. In the present work the assessment of hy2Foam to solve hypersonic complex flow features with strong interactions including non-equilibrium effects was demonstrated. Freestream conditions with stagnation enthalpy of 5.44 MJ/kg and Mach number of 12.2, for the double cone case, and stagnation enthalpy of 5.07 MJ/kg and Mach number of 11.3 for the hollow cylinder case were considered. Comparison with newer existing numerical data and experimental data from LENS XX (Large Energy National Shock Expansion Tunnel Version 2) was also performed. Special attention was taken to the phenomenon of vibrational excitation of the molecules. Different vibrational non-equilibrium models were used and compared with the available data. Hy2Foam showed consistent results, with the vibrational non-equilibrium models reducing the discrepancies between numerical and experimental results.