On solid trioxane combustion in stagnation point flows

Abstract

Response, flame structure, and extinction limits of solid trioxane (C 3 H 6 O 3 ) combustion in stagnationpointflows are computationally studied with detailed chemistry, transport properties, and radiation representation. While a solid surface radiation model addresses emission and absorption by the surface, a narrowband radiation model, with carbon dioxide, carbon monoxide, and water vapor as the gas-phase participating media, is employed to describe the gas-phase and surface radiation is presented over the flammable regime, with emphasis on the low-stretch regine of the radiatively participating flames. When only surface radiation is included, two extinction limits exist, namely the blow-off limit and the low-stretch radiative limit, and the burning rates and maximum flame temperatures are lower than those of the adiabatic counterpart, as expected. With the inclusion of surface and gas-phase radiation, results show that, while flame temperatures are even lower, the burning rate of the trioxane diffusion flame may actually exceed the adiabatic limit and increase at low stretch rate due to radiative feedback from the flame to the surface. Reaction pathways leading to trioxane oxidation are also analyzed. High-temperature and lowtemperature reaction pathways identified previously in homogeneous kinetics studies are sustained in heterogeneous trioxane combustion. Furthermore, potential effects of radical recombination at the solid surface are assessed and discussed.