Simulation of radiation generated by chemical reactions in weakly ionized shock waves using DSMC

In this work, we simulate the radiation from the NO and N⁺ ₂ systems and compare with the shock tube experiments in air by Gorelov.1 The related shock speeds are high enough to have produced a peak translational temperature of ~20,000 K or even higher, providing enough energy to ionize some of the flow species. In the current work, we simulate ionized normal shock flows by implementing appropriate ionization models in a 11 species air (N, O, N₂, O₂, NO, N⁺, O⁺, N⁺ ₂, O⁺ ₂, NO₊ and e-) in DSMC. Electron impact and heavy particle impact excitation for NO is studied using the Quasi-Steady-State (QSS) approximation to compute the NO(A²IeΣ⁺_u) and the N⁺ ₂ (B₂IeΣ⁺ _u) state number densities. Line-by-line calculation of the spectra is performed using the NEQAIR2 code to obtain radiation in the wavelength range of 235 ± 7 and 391:4 ± 0:2 nm. For shock speeds above 7 km/s, the currently calculated radiation are in better agreement with the experimental data than that in our eariler work,3 but are still about 2~6 times lower than the experiments. For the N⁺ ₂ radiation good agreement with the experimental data is obtained for shock speeds above 9 km/s.