Modeling Gas Radiative Properties in a Rocket Motor Plume

This study compares several band models for calculating the thermal radiation from the plume of a simulated rocket motor. First, a non-scattering plume is considered allowing one to use the line-of-sight integration (LOS). The results for three band models are compared. Next we study a scattering plume. The radiative heat transfer equation is solved numerically using the axisymmetric finite volume method (FV). Detailed analysis of the numerical scheme of the FV method demonstrated that it has a large numerical diffusion term which, although formally of the first order, in practice can cause large errors in calculating thermal signatures of hot jets. The numerical scheme was hence modified using what we call the “quasi-Cartesian” approach. We demonstrate that for a non-scattering media in the first order the numerical diffusion term vanishes and the modified scheme formally reduces to the integration along the line of sight resulting in a very good agreement between the FV and LOS predictions. The new method is then used to calculate radiation from a scattering plume and the results for two band models are compared.