The infra-red signature of a hot scattering plume calculated by the SCATAX method

The Sowerby Research Centre of British Aerospace has developed an infrared predictive code, SIRUS, which models the signature of an air platform. We review briefly this code, and proceed to the calculation in code SCATAX of gas radiative transfer in a plume containing scattering particles. An accurate radiative-transfer calculation of the signature of plume containing scattering particles is complex and costly: it is necessary for rocket engines , but may not be so for air-breathing engines (where only the properties along the single detector line-of-sight are involved). We describe the physical basis of radiative-transfer with scattering, its implementation in the SCATAX code, present some quantitative results, and discuss the important ‘searchlight’ effect.