Nonequilibrium chemical and radiation coupling. I - Theory and models. II -Results for AOTV flowfields

A flowfield model for the stagnation region of high-altitude entry vehicles which includes nonequilibrium chemistry, multitemperature, viscous, conduction, and diffusion effects is presented. The model contains coupled nongray nonequilibrium radiative transfer and accounts for local thermodynamic nonequilibrium phenomena for both atoms and molecules. Several approaches for modeling electron-electronic energy are presented ranging from a quasiequilibrium free electron model to a full electron-electronic equation. Comparison with Fire 2 flight data verifies that the model is reasonably accurate. Based on these results for Fire 2 radiation cooling/coupling is measurable and important, the wavelength character of the radiative heat transfer varies with time, and local thermodynamic nonequilibrium is important and should be included.