Assessment of turbulence–chemistry interaction models on infrared radiation of rocket exhaust plumes

In this study, different turbulence–chemistry interaction (TCI) models were used to assess the chemically reacting flow field and infrared signatures of a rocket exhaust plume. The radiative properties of the gases were determined using the statistical narrow-band model, and the line-of-sight method was used to compute the infrared radiation intensity by solving the radiative transfer equation. The numerical analysis quantified the TCI effects on the rocket exhaust plume, including the thermal properties, species concentrations, and infrared signatures. The prediction accuracies of six widely used TCI models for infrared radiation calculations were evaluated based on measurement data from typical solid rocket motor ground tests. The results showed that the eddy-dissipation concept (EDC) model yielded significantly lower predictions of the peak temperature, species concentrations, and infrared radiation intensity than the other models. These discrepancies were most pronounced under ground-level conditions. Specifically, the maximum axial temperature difference reached 350 K, while the maximum relative differences in the predicted concentrations of CO and H₂ were 58% and 62%, respectively. The peak spectral radiant intensity showed a maximum difference of 50% to 60%. All of these deviations decreased with increasing altitude. The optimal infrared prediction model varies depending on the spectral band. For the 2.7 μm, 4.3 μm, and 1.5–5 μm bands, the TCI models that achieved the highest infrared radiation prediction accuracy were the SST k - ω FR model, the Realizable k -ε FR model, and the Realizable k - ε FR/EDM model, with respective deviations from experimental measurements of 8.15%, 0.53%, and 2.28%.