Vibronic State-Specific Modelling of High-Speed Nitrogen Shocked Flows. Part II: Shock Tube Simulations

TL;DR

This study models nitrogen shock tube flows using a vibronic state-specific approach, revealing discrepancies in radiative intensity predictions and highlighting the need to consider additional shock tube phenomena for accurate simulations.

Contribution

It introduces a vibronic state-specific model into shock tube simulations and analyzes its performance against experimental data, identifying key factors affecting accuracy.

Findings

Peak radiative intensities were underestimated by 1-2 orders of magnitude.

Model correctly predicted intensity profiles for low-speed shots.

Discrepancies suggest other phenomena like radiation absorption and heat conduction are influential.

Abstract

The conditions of thermochemical and radiative non-equilibrium attained in nitrogen shocked flows were quantified using a vibronic state-specific model. This model, being described in a companion paper, was implemented in Euler one-dimensional simulations for shots $19$, $20$ and $40$ of the EAST's $62^{\textrm{th}}$ campaign. It was found that the peak values of the instrumental radiative intensities were underestimated by one to two orders of magnitude, and sensitivity tests performed on several parameters of the simulations were not successful in getting a reasonable agreement. The shapes of the instrumental radiative intensities' profiles obtained in the low speed shot were correctly predicted, unlike the ones of the medium and high speed shots which revealed non-null plateaus proceeding or coalescing with peaks. These plateaus were not predicted at all. It is suspected that such discrepancies may have resulted from neglecting other shock tube related phenomena, as pointed out by other researchers in the literature: the absorption of radiation emitted by the driver gas and the EAST electric arc, and/or the conduction of heat due to downstream plasma being subjected to a stronger shock wave.