Fig. 1. Schematic diagram of LOS

Fig. 2. Ray tracing model of RMC in participating media

Fig. 3. Molecular line intensity distribution of HITRAN

Fig. 4. The single molecule spectral absorption coefficients for the 3-5 μm and 8-14 μm wavelength ranges based on HITRAN

Fig. 5. Error analysis of the spectral absorption coefficient for H₂O

Fig. 6. Error analysis of the spectral absorption coefficient for CO₂

Fig. 7. Error analysis of the spectral absorption coefficient for CO

Fig. 8. Single-molecule spectral absorption coefficients in the HITEMP database

Fig. 9. Error analysis of the spectral absorption coefficient for CO

Fig. 10. The computation of spectral radiation intensity for a one-dimensional non-isothermal homogeneous plate

Fig. 11. The spectral absorption coefficient and radiation intensity distribution of a mixed gas

Fig. 12. The absorption coefficient of a single molecule and the distribution of radiation intensity with wavenumber

Fig. 13. Absolute discrepancy between the single-molecule Planck average absorption coefficient and spectral radiation intensity

Fig. 14. Schematic diagram of the calculation domain of the exhaust system

Fig. 15. The temperature distribution of the exhaust system

Fig. 16. The pressure distribution of the exhaust system

Fig. 17. Analysis of the calculation results of infrared radiation imaging with small angle: (a) 0°; (b) 5°; (c) 10°; (d) 15°

Fig. 18. Comparison of calculated results of spectral radiation intensity at the front and rear

Fig. 19. The variation of integral radiation intensity with the azimuth angle

Fig. 20. The absolute error of the calculation results of the integral radiation intensity of the convergent nozzle under different azimuth angles