Computational Modeling of the Structure and Extinction of Flame Balls in a Microgravity Environment

Combustion models that simulate pollutant formation and study chemically controlled extinction limits in flames often combine detailed chemical kinetics with complicated transport phenomena. One of the simplest models in which these processes are studied is the plane premixed laminar flame. This problem is appealing due to its simple flow geometry and it has been used by kineticists in understanding elementary reaction mechanisms in the oxidation of fuels. Although premixed flames have been studied extensively (experimentally and numerically) in a normal Earth based gravity environment, there is relatively little experimental and virtually no numerical investigations of these systems in a microgravity environment. To this end, we have begun a program designed to study computationally the effects of radiation losses on spherically symmetric premixed hydrogen-air flames in a microgravity environment in which there are no convective flows. We are considering a detailed transport and finite rate multistep kinetics model. To be able to compute solutions (both stable and unstable) in the neighborhood of the lean and rich extinction limits, we must modify the basic solution algorithm to include an arclength continuation procedure. In this way a parameter such as the equivalence ratio can be varied while still having a computationally stable algorithm.