Breakdown Behavior in Air and n-Butane Mixtures Leading to Combustor Ignition Modeled using Effective Ionization Coefficients

The process of electron attachment in electronegative air-hydrocarbon gas mixtures can be an impediment to the arc ignition process in a combustion engine. The optimized conditions to produce ignition include a gas mixture with a minimal ionization coefficient. Data on ionization rates and ion reactions in various air-hydrocarbon mixtures is necessary, though, for a proper theoretical analysis of the ignition process. The known set of cross-sections and rate constants for simple methane (CH$_{4})$ is often used and results extrapolated to heavier hydrocarbons. Recently, experimental data on cross-sections, ionization rates and ion reactions in n-butane (n-C$_{4}$H$_{10})$ were reported which allow for reliable models of ignition in more complex fuel mixtures. This paper presents an analysis of breakdown and ignition using air and n-butane mixtures.