Chemical reactions and ignition initiation in hydro carbon-air mixtures by high-voltage nanosecond gas discharge

Investigation of the combustible mixture ignition by nanosecond high-voltage volume discharge requires the detail knowledge of kinetic processes in the discharge itself and its afterglow. Main electrodynamic characteristics, such as velocity of discharge propagation and energy consumption were measured in hydrogen, methane and hydrogen-air, methane-air stochiomethric mixtures in a pressure range 1-20 Torr under the action of 15 kV, 5 ns rise time and 25 ns duration high voltage pulses of negative and positive polarity with a repetitive frequency of 40 Hz. Simultaneous control of time-resolved (both in nanosecond and tenth-second time scale) behaviour of emission of different excited components in the wavelength range of 190-800 nm gives data set for detail analysis of the chemical kinetics in discharge and its afterglow in methane-air mixtures. Numerical modeling of the process of ignition for H₂-air, CH₄-air, C₂H₆-air, C₄H₁₀-air, C₇H₁₆- air and C₈H₁₈-air mixtures at high temperatures under the action of fast ionization wave (FIW) was performed. The ignition threshold shifts for different mixtures gas pressures, temperatures and equivalent ratios were obtained; the analysis of ignition efficiency, which enables to plan the experimental measurements of the initiation of ignition by FIW at high temperatures, was provided; detailed investigation was provided of the dependence of ignition delay time from the energy release in the discharge, reduced electric field value, initial gas temperature, type of excitation and mixture composition.