Consistent Comparison of Macroscopic and State-to-State Kinetics in Hypersonic Flows

Abstract

We present a comparison of numerical results in strongly expanding hypersonic flows that have been obtained using state-to-state and macroscopic thermochemical models. The macroscopic model, which includes direct cross coupling between chemical and vibrational relaxation, has been derived directly from the state-to-state kinetic rates. This makes the comparison the most consistent possible, as differences cannot be ascribed to original discrepancies in the used rates. The comparison is conducted in a N2-N system using the test conditions of the EAST facility nozzle experiment, for which experimental data are available. Nomenclature

Different Approximation Levels in Using CFD for the Design of Hypersonic Vehicles

“…Details about the used thermochemical models and numerical method can be found in [16]. The numerical prediction aims at reproducing one of the experiments conducted in the NASA Ames EAST facility nozzle by Sharma, et al [17,18].…”

3D nozzle flow simulations including state-to-state kinetics calculation

“…This model consists in writing a continuity equation for the population of each vibrational level of molecules, determining species densities and their internal distributions [2], including not only vibrational states, but also electronically excited states [3] as well as non-maxwellian electron energy distribution functions (EEDF) by solving an adequate Boltzmann equation [4,5]. With few exceptions (see [6,7,8]), applications of the STS approach to high enthalpy flow simulation have been very limited, due to the significant computing time required to conduct even 1-D simulations [9,10,11].…”