Combustion and chemical kinetics study of jet fuel, biogas and solid fuel in diffusion flames

This study is organized into three parts focusing on jet fuel combustion, biogas combustion, and solid fuel microgravity combustion.;In Part I, combustion and chemical kinetics of high molecular weight hydrocarbon blends at the onset of soot formation are studied. The chemical structure of ethylene counterflow diffusion flames doped with trace amounts of jet fuel or two promising jet fuel surrogates is analyzed by gas sampling via quartz microprobes and GC/MS. A dataset for the pyrolysis, oxidation and sooting behavior of jet fuel in diffusion flames is provided. The critical fuel decomposition products and soot precursors, such as acetylene, benzene and toluene, are compared to evaluate surrogate formulations. The data for C7-C12 alkanes are consistent with typical decomposition of large alkanes with both surrogates (6 and 2-component) showing good qualitative agreement with jet fuel in their pyrolysis trends. The acetylene profiles present a unique multimodal behavior. Good agreement between jet fuel and the surrogates is found with respect to critical soot precursors such as benzene and toluene.;In Part II, combustion and kinetics of biogas, which is a viable alternative gas turbine fuel, is modeled in premixed and non-premixed configurations. A modeling study is conducted on blends of CH4 and CO2 simulating biogas from digestion plants or landfills to compare predictions for four non-sooting counterflow diffusion flames and to examine their thermal and chemical structure. In addition to evaluation of thermal influences of biogas CO2, the chemical influences of CO2 are quantified because CO2 dilution through chemical effects is shown to reduce soot precursors, emissions of NOx and greenhouse gases even without flame temperature reduction.;In Part III, diffusion flames spreading near solid fuel surfaces are investigated numerically and analytically in 2-D domains for both unconfined and confined environments. A model of surface-attached solid fuel flames with weak convection is constructed. Flame spread over thin fuels is studied in a confined geometry because of its implications for fire safety in normal gravity. It is demonstrated that the buoyancy is suppressed in the MSU Narrow Channel Apparatus, which produces test conditions that can simulate conditions achieved in actual microgravity.