COMPATIBILITY OF INFRARED BAND MODELS WITH SCATTERING

Techniques for the computation of radiative heating from aluminized so lid propellant rocket exhaust plumes must account for infrared emissio n and absorption by hot H2O and CO2 in the presence of strong three-di mensional aerosol scattering by micron-sized Al2O3 droplets and partic les. Radiative heating computations are usually performed over wide sp ectral intervals using infrared band models. However, no rigorous exte nsion to infrared band models has been proposed for situations with sc attering. Indeed, band models and scattering are widely held to be inc ompatible. Practical engineering calculations of plume radiative heati ng have therefore proceeded, using various approximations to the trans port equation. Although the errors in these approximations are believe d to be reasonably small, they have never been quantified because of t he lack of rigorous results. In order to help remedy this deficiency, this article develops two different rigorous solutions. Although they are currently restricted to homogeneous media, they nevertheless provi de a previously unavailable means or calibrating code performance and assessing the accuracy of various approximation schemes. Some sample a pplications are provided for the Space Shuttle Solid Rocket Booster.